fix: close what nine adversarial reviews found, most of it mine

Nine focused reviews (export state machine, upload path, auth/abuse, client
queue, guest UI, database, deploy/ops, regression hunt, test honesty). Every
finding below was re-verified against the code before being acted on; several
plausible-sounding ones were checked and rejected.

## Data loss and denial of service

**One request could OOM-kill the app container.** `client_upload_id` was read
with `Field::text()` — axum builds its multipart reader with no SizeLimit, so
the only bound was the route's 576 MiB body limit, then decoded into a second
full String. `caption` and `hashtags` go through `read_text_field_bounded` for
exactly this reason; this field arrived later and missed it. Any guest, one
request, and every SSE stream drops and every in-flight temp file is stranded.

**Nothing bounded concurrent upload bodies.** The headroom gate can only refuse
to COMMIT — the body is already streamed to a temp file by the time it runs, and
neither axum, the tower stack nor Caddy limits how many stream at once. ~100
guests tapping "upload all" after the ceremony puts 10-20 GB of .tmp on a 40 GB
volume, invisible to the gate, eating the reserve that keeps Postgres able to
write WAL. New `UploadAdmission` budgets bytes (not requests, so one video and
two hundred photos coexist) via a permit that releases on drop, so every exit
path returns it.

**The export decode bypassed the memory permit the compression path takes.**
Same class of work — decode + resize every image in the gallery — in a bare
spawn_blocking. A release fired while the last photos were still compressing put
both in the same 1 GiB cgroup; the OOM kill marks the export failed and
`recover_exports` re-spawns it into the same conditions on the next boot. The
permit is now process-wide in `imaging`, because the constraint it expresses is
the container's memory, not one worker's.

**`MediaTotalCache` cached its own failure as 0.** For the whole TTL the gate
then saw an empty event and collapsed to the flat reserve — the behaviour the
two-halves design replaced — with no log line. And the trigger correlates with
the danger: with max_connections 10 the query fails exactly during a burst. Now
falls back to the last good reading and says so.

**V8's heap ceiling sat above the frontend container's entire budget** (measured:
259 MB inside a 256M limit), so GC could never intervene and the only
backpressure was SIGKILL under an arrival burst.

## Guest-visible

**The feed stopped being newest-first after the first reconcile.** It fetches
whole 100-item server pages while `uploads` grows in 20s, so everything in the
gap was absent from `present`, classified as new, and prepended — ~80 photos
from earlier in the evening above the newest ones. It also stalled infinite
scroll, since the cursor still pointed at item 20 and the observer only re-fires
on a change. The union is now sorted on the server's own (created_at, id) key,
which additionally places an SSE arrival correctly.

**A stale `loadMoreError` outlived every refresh and filter change**, leaving a
false error above a button that returns immediately on `!nextCursor`.

**A failed derivative toasted "Ein Upload konnte nicht verarbeitet werden."** for
a photo sitting right there on screen — the handler still assumed 1d9fb11's
pre-fix behaviour (row deleted, quota refunded, card evicted), none of which is
true any more. It was the last surviving route for the "your photo is gone"
signal that fix set out to remove.

## Enforcement that existed only in comments

`recover_name_rate_per_15min` is clamped at the point of use: the ordering
`3 x ceiling <= PIN_LOCK_THRESHOLD` is the whole control against one source
locking any guest whose name is on the feed, it was asserted in a comment, and
`patch_config` accepted 1..100_000. The test pinned the default constant rather
than the enforced bound; it now pins the bound.

## Tests that could not fail

- The gate test asserted only its own premise (`500MB x 100 > 35GB`) and never
  touched the gate. It now checks both controls against the same state and
  requires them to disagree in the right direction.
- `the_banner_always_fires_before_the_upload_gate_closes` reduced to
  `G < G + G/4` — true for any margin, including zero, so it could not detect
  the banner moving to exactly the gate. It now pins the gap.
- `disk_is_low`'s `free < LOW_DISK_FLOOR_BYTES` clause was unreachable (warn_at
  is always >= 12.5 GB against a 10 GB floor). Two tests were named after it and
  neither could fail if it were deleted. Clause and constant removed.
- The suspension test I added last commit hard-coded the credit cap instead of
  importing it, so changing STALL_TIMEOUT_MS would leave it passing against a
  system that no longer exists. Now imports MAX_SUSPEND_CREDIT_MS.

## Stale comments corrected

The prune doc still argued at length for the pre-build ordering that 1d9fb11
reversed — a reader trusting it would reopen the blocker 0506369 fixed.
DISK_RESERVE_BYTES claimed to equal the banner threshold that 0506369
deliberately offset by 25%. And host.rs kept its own duplicate 10 GB literal
instead of importing the constant.

154/154 backend, 59/59 vitest, clippy clean, svelte-check 0 errors, eslint
clean, both builds, compose + caddy validate.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.claude/settings.json

@@ -0,0 +1,9 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(cargo check *)",
+      "Bash(cargo clippy *)",
+      "Bash(git --no-pager diff *)"
+    ]
+  }
+}

.env.example

@@ -1,30 +1,77 @@
 # ── Domain ────────────────────────────────────────────────────────────────────
 # Public domain Caddy will serve and obtain a TLS certificate for.
+#
+# The DNS A record must already point at this server BEFORE the first `up -d`: Caddy
+# requests a certificate on boot, and Let's Encrypt allows only 5 failed validations per
+# hostname per hour. Never delete the caddy_data volume — it holds the certificate and
+# the ACME account key.
 DOMAIN=my-event.example.com
 
+# ── Image version ─────────────────────────────────────────────────────────────
+# Tag pulled for the `app` and `frontend` services (docker-compose.yml). Production runs
+# prebuilt images from the registry and never compiles — see DEPLOYMENT_RUNBOOK.md.
+# Always an immutable tag, never `latest`: rollback is `EVENTSNAP_VERSION=<previous>`
+# + `docker compose up -d`, which works offline if that image is still resident locally.
+EVENTSNAP_VERSION=v0.13.0
+
 # ── App server ────────────────────────────────────────────────────────────────
 APP_PORT=3000
-# docker-compose.yml already forces APP_ENV=production for the `app` service.
-# Only set this for a non-compose (bare cargo) run; leave unset for local dev.
-# APP_ENV=production
+# Set to `production` in real deployments. This activates the secret guard that
+# refuses to boot with placeholder JWT_SECRET / ADMIN_PASSWORD_HASH values.
+# (docker-compose.yml already sets APP_ENV=production for the app service.)
+APP_ENV=production
 
 # ── Database ──────────────────────────────────────────────────────────────────
-# Set a strong password and keep it identical in DATABASE_URL and POSTGRES_PASSWORD.
-DATABASE_URL=postgres://eventsnap:CHANGE_ME_strong_db_password@db:5432/eventsnap
+# Set a strong password and keep it in sync between DATABASE_URL and
+# POSTGRES_PASSWORD. Generate one with: openssl rand -hex 24
+#
+# SET THIS BEFORE THE FIRST `docker compose up -d`. Postgres reads POSTGRES_PASSWORD
+# only when it initialises its data directory, on that very first boot. Change it
+# afterwards and the app authenticates with the new password against a volume still
+# holding the old one — a permanent restart loop ("password authentication failed").
+# The only ways out are restoring the old password or `docker compose down -v`, which
+# deletes the database, the media and the exports. In production the app refuses to
+# boot while this is still the placeholder below, so it cannot be missed by accident.
+DATABASE_URL=postgres://eventsnap:CHANGE_ME_use_a_strong_password@db:5432/eventsnap
 POSTGRES_USER=eventsnap
-POSTGRES_PASSWORD=CHANGE_ME_strong_db_password
+POSTGRES_PASSWORD=CHANGE_ME_use_a_strong_password
 POSTGRES_DB=eventsnap
+# Connection pool size. The code default is 10 (backend/src/db.rs) — set it explicitly,
+# because a `.env` written by hand from this file's secrets is otherwise silently on 10.
+#
+# SIZE IT TO THE CORES, NOT TO THE GUESTS. The earlier advice here was ~30, reasoned from
+# "~100 guests polling the feed at once" back when a feed page cost ~449 ms and connections
+# were spent waiting. Migration 024 replaced the feed view's GROUP BY with scalar subqueries
+# and a page now costs well under a millisecond, so concurrency is no longer where the time
+# goes. On a 2 vCPU box 30 simultaneous queries cannot run — they queue on the CPU instead of
+# on the pool, which is the same wait wearing a different hat, and 30 Postgres backends plus
+# shared_buffers is snug in the 1G that docker-compose.yml allots `db`.
+#
+# 15 on 2 vCPU / 4 GB. Raise toward 30 only alongside more cores AND a bigger `db` memory
+# limit — an OOM in Postgres doesn't degrade one feature, it takes the whole event down.
+DATABASE_MAX_CONNECTIONS=15
+
+# Log level: see the "Logging" section near the bottom of this file.
+#
+# Defined THERE and nowhere else, deliberately. This file used to assign RUST_LOG twice —
+# once here and once there — and Compose takes the LAST assignment, so editing this line to
+# `debug` to chase a problem during the event changed nothing at all, silently. A key that
+# appears twice in a .env is a trap regardless of which value is better.
 
 # ── Authentication ────────────────────────────────────────────────────────────
-# REQUIRED in production: generate with `openssl rand -hex 64` (128 hex chars).
-# The backend refuses to start in production with this placeholder or any value
-# that is short or contains change/example/placeholder/replace.
+# Generate with: openssl rand -hex 64
 JWT_SECRET=change_me_to_a_random_64_byte_hex_string
 SESSION_EXPIRY_DAYS=30
 
 # Admin dashboard password (bcrypt hash).
-# Generate with: htpasswd -bnBC 12 "" yourpassword | tr -d ':\n'
-ADMIN_PASSWORD_HASH=$2y$12$placeholder_replace_me
+# Generate with an image the stack already pulls (htpasswd needs apache2-utils, which
+# a stock VPS does not have):
+#   docker run --rm caddy:2-alpine caddy hash-password --plaintext 'yourpassword'
+# IMPORTANT: keep the SINGLE QUOTES. A bcrypt hash is full of `$` (e.g. $2b$12$…$…),
+# and both Docker Compose's env_file interpolation and dotenvy's variable substitution
+# would otherwise eat the `$…` segments (reading them as unset vars) and corrupt the
+# hash — every admin login then 401s. Single quotes make both read it literally.
+ADMIN_PASSWORD_HASH='$2y$12$placeholder_replace_me'
 
 # ── Event ─────────────────────────────────────────────────────────────────────
 EVENT_NAME=Max & Maria's Wedding
@@ -32,20 +79,101 @@ EVENT_SLUG=max-maria-2026
 
 # ── Storage ───────────────────────────────────────────────────────────────────
 MEDIA_PATH=/media
+# Export archives (Gallery.zip / Memories.zip). MUST be outside MEDIA_PATH —
+# /media is publicly served, so exports here would be downloadable without auth.
+EXPORT_PATH=/exports
 
-# ── Upload limits ─────────────────────────────────────────────────────────────
-DEFAULT_MAX_IMAGE_SIZE_MB=20
-DEFAULT_MAX_VIDEO_SIZE_MB=500
-
-# ── Rate limiting ─────────────────────────────────────────────────────────────
-DEFAULT_UPLOAD_RATE_PER_HOUR=10
-DEFAULT_FEED_RATE_PER_MIN=60
-DEFAULT_EXPORT_RATE_PER_DAY=3
-
-# ── Capacity ──────────────────────────────────────────────────────────────────
-DEFAULT_ESTIMATED_GUEST_COUNT=100
-# Fraction of total storage that triggers the "low storage" warning (0.0–1.0)
-DEFAULT_QUOTA_TOLERANCE=0.75
+# ── Runtime settings (upload limits, rate limits, capacity) ───────────────────
+# NOTE: These are NOT environment variables. Upload size caps, rate limits, guest
+# count and quota tolerance are stored in the database `config` table (seeded once
+# at first boot) and changed at runtime from the ADMIN DASHBOARD — the backend does
+# not read them from .env. Setting them here has no effect. Current seeded defaults:
+#   upload rate      100 / hour / guest   (raised from 10 by migration 015)
+#   feed rate         60 / minute
+#   export rate        3 / day
+#   max image size    20 MB
+#   max video size   500 MB
+#   estimated guests 100
+#   quota tolerance  0.75  (see below — NOT a warning threshold)
+# Adjust these in the admin UI before the event if needed.
+#
+# quota_tolerance is the MULTIPLIER IN THE PER-USER QUOTA FORMULA, not the point at
+# which anything warns you:
+#
+#     per_user_limit = floor(free_disk * quota_tolerance / active_uploaders)
+#
+# It is recomputed against LIVE free space on every upload, so it self-throttles: guests
+# converge on a fixed point at tolerance/(1+tolerance) of the free space you started
+# with — 43% at 0.75, i.e. ~30 GB of a fresh 70 GB.
+#
+# Raising it therefore AUTHORISES GUESTS TO FILL MORE OF THE DISK. Setting 0.95 in the
+# belief that it means "warn me later" moves the fixed point to ~49% and eats the
+# headroom the keepsake needs — and the keepsake needs a lot, because Gallery.zip and
+# Memories.zip are each roughly a second copy of every original (both store media
+# uncompressed). Budget for media + 2x media, or move exports to their own volume.
+#
+# 0.75 is the tested default. Lower it if the box is tight; raise it only if you have
+# provisioned export headroom separately.
 
 # ── Workers ───────────────────────────────────────────────────────────────────
+# Number of parallel media compression workers. Default 2. Boot-time only.
+#
+# CORRECTION TO EARLIER GUIDANCE: this used to say "each worker can run an ffmpeg
+# transcode, so raise the app memory limit to ~2G if you set 4". There is NO video
+# transcode anywhere in this codebase — services/video.rs runs
+# `ffmpeg -ss <t> -i <src> -vframes 1 -vf scale=...`, a single poster frame, and video
+# originals are stored and served byte-for-byte. Poster extraction costs ~150-250 MB
+# for a moment; it is not the constraint.
+#
+# The real memory consumer is the IMAGE path. `image` 0.25's resize builds an Rgba32F
+# intermediate at 16 BYTES PER PIXEL, sized (source_width x target_height) — which the
+# 256 MiB decode guard in imaging.rs does NOT cover. Peak per photo, decode + the 2048px
+# display resize: ~145 MB at 12 MP, ~223 MB at 24 MP, ~354 MB at 48 MP.
+#
+# So on a 2 vCPU / 4 GB box (e.g. Hetzner CX22) KEEP THIS AT 2:
+#   * concurrency 4 would put two giants at ~1.5 GB against the 1G app limit — OOM.
+#   * and app=2G + db=1G + frontend/caddy 256M each + ~370 MB of OS/Docker exceeds the
+#     ~3910 MiB a "4 GB" VM actually reports. Raising the limit oversubscribes the host.
+# 4 is only reasonable on the 4 vCPU / 8 GB box README.md documents.
+#
+# The "two 48 MP photos at once" worst case this number used to be sized against is no
+# longer reachable: compression.rs takes an EXCLUSIVE `heavy` permit for any job whose
+# estimated peak exceeds HEAVY_IMAGE_BYTES (150 MiB), so two giants serialise no matter what
+# this is set to. What concurrency 2 now buys is two ORDINARY phone photos in parallel
+# (~145 MB peak each), which is both memory-safe and short enough not to starve the two
+# tokio worker threads a 2 vCPU box gets.
+#
+# Do NOT drop this to 1 hoping to protect the CPU. It halves throughput on the common light
+# path for a heavy path that is already serialised, and a longer compression backlog means
+# more feed tiles served from full-size originals (VirtualFeed falls back to /original while
+# derivatives are pending) — trading a little CPU for a lot of venue-wifi bandwidth.
+#
+# Throughput at 2 is not the bottleneck anyone thinks it is: ~2.5s per 12 MP photo, so
+# 100 photos is ~250 CPU-seconds spread over an entire evening.
 COMPRESSION_WORKER_CONCURRENCY=2
+
+# ── Comments ──────────────────────────────────────────────────────────────────
+# Master switch for the comment feature. Boot-time only (NOT in the admin UI), so it
+# needs a `docker compose up -d` to apply. Anything other than false/0/no/off is on.
+#
+# When false the backend rejects NEW comments with 403 and the frontend hides the whole
+# comment UI, including in the offline keepsake viewer. Likes and captions are entirely
+# separate features and are unaffected. Existing comments stay in the database (hidden),
+# so flipping it back restores them.
+#
+# Note it gates POSTING only: GET /upload/{id}/comments still serves already-existing
+# comments, and the keepsake's data.json still embeds their text. Irrelevant if the flag
+# is off from the first boot, since no comment can ever have been written.
+# NOTE for the current deployment: `docker-compose.yml` PINS this to "false" on the app
+# service, and `environment` overrides `env_file` — so changing it here has no effect in
+# production. Remove that line from the compose file first if you want comments back.
+COMMENTS_ENABLED=true
+
+# ── Logging ───────────────────────────────────────────────────────────────────
+# SET THIS IN PRODUCTION. Without it the app falls back to
+# `eventsnap_backend=debug,tower_http=debug` (see main.rs), and with TraceLayer that is a
+# debug line per HTTP request — including every preview and thumbnail fetch. Combined with
+# Docker's json-file driver it writes to the same filesystem as the database and the media.
+# docker-compose.yml caps each service's logs at 30 MB; this keeps the volume sane in the
+# first place. The e2e stack has always used exactly this value.
+RUST_LOG=eventsnap_backend=info,tower_http=warn

.env.test

@@ -1,45 +0,0 @@
-# ── Domain ────────────────────────────────────────────────────────────────────
-# Public domain Caddy will serve and obtain a TLS certificate for.
-DOMAIN=my-event.example.com
-
-# ── App server ────────────────────────────────────────────────────────────────
-APP_PORT=3000
-
-# ── Database ──────────────────────────────────────────────────────────────────
-DATABASE_URL=postgres://eventsnap:secret@db:5432/eventsnap
-POSTGRES_USER=eventsnap
-POSTGRES_PASSWORD=secret
-POSTGRES_DB=eventsnap
-
-# ── Authentication ────────────────────────────────────────────────────────────
-# Generate with: openssl rand -hex 64
-JWT_SECRET=change_me_to_a_random_64_byte_hex_string
-SESSION_EXPIRY_DAYS=30
-
-# Admin dashboard password (bcrypt hash).
-# Generate with: htpasswd -bnBC 12 "" yourpassword | tr -d ':\n'
-ADMIN_PASSWORD_HASH=$2y$12$placeholder_replace_me
-
-# ── Event ─────────────────────────────────────────────────────────────────────
-EVENT_NAME=Max & Maria's Wedding
-EVENT_SLUG=max-maria-2026
-
-# ── Storage ───────────────────────────────────────────────────────────────────
-MEDIA_PATH=/media
-
-# ── Upload limits ─────────────────────────────────────────────────────────────
-DEFAULT_MAX_IMAGE_SIZE_MB=20
-DEFAULT_MAX_VIDEO_SIZE_MB=500
-
-# ── Rate limiting ─────────────────────────────────────────────────────────────
-DEFAULT_UPLOAD_RATE_PER_HOUR=10
-DEFAULT_FEED_RATE_PER_MIN=60
-DEFAULT_EXPORT_RATE_PER_DAY=3
-
-# ── Capacity ──────────────────────────────────────────────────────────────────
-DEFAULT_ESTIMATED_GUEST_COUNT=100
-# Fraction of total storage that triggers the "low storage" warning (0.0–1.0)
-DEFAULT_QUOTA_TOLERANCE=0.75
-
-# ── Workers ───────────────────────────────────────────────────────────────────
-COMPRESSION_WORKER_CONCURRENCY=2

.github/workflows/audit.yml

@@ -0,0 +1,73 @@
+# Dependency advisory scan.
+#
+# Lives in .github/workflows/ because Gitea Actions scans BOTH .gitea/workflows and
+# .github/workflows, and e2e.yml already proves this instance resolves `actions/*` from GitHub
+# (DEFAULT_ACTIONS_URL). Keeping one directory avoids a split where half the CI is invisible
+# depending on which convention you look under.
+#
+# Unlike the GitHub-hosted runners this workflow does NOT assume a preinstalled Rust toolchain —
+# the common Gitea runner images (gitea/runner-images, catthehacker/ubuntu) ship Node and Docker
+# but not cargo. So we install it explicitly instead of relying on the ambient environment.
+name: Audit
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+  schedule:
+    # New advisories land against unchanged code, so a push-only trigger would never see them.
+    - cron: '0 6 * * 1'
+
+jobs:
+  cargo-audit:
+    name: cargo audit (backend)
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        run: |
+          if ! command -v cargo > /dev/null; then
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal
+            echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
+          fi
+
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/bin
+          key: cargo-audit-${{ hashFiles('backend/Cargo.lock') }}
+          restore-keys: cargo-audit-
+
+      - name: Install cargo-audit
+        run: cargo install cargo-audit --locked || true
+
+      # `rsa` 0.9 (RUSTSEC-2023-0071, "Marvin") is a transitive dep of the SQLx MySQL driver that
+      # this app never exercises: auth is HS256 + bcrypt, and the only database is Postgres. There
+      # is no patched release, so failing the build on it would mean a permanently red pipeline
+      # that everyone learns to ignore — which is worse than not scanning at all. Ignore it
+      # SPECIFICALLY, so that any OTHER advisory still fails the job.
+      - name: Audit
+        working-directory: ./backend
+        run: cargo audit --deny warnings --ignore RUSTSEC-2023-0071
+
+  npm-audit:
+    name: npm audit (frontend)
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+      - name: Install deps
+        working-directory: ./frontend
+        run: npm install
+      # Production dependencies only: a dev-only advisory (build tooling, test runners) can't be
+      # reached by a guest at the party, and gating merges on it just trains people to skip the gate.
+      - name: Audit
+        working-directory: ./frontend
+        run: npm audit --omit=dev --audit-level=high

.github/workflows/checks.yml

@@ -0,0 +1,129 @@
+# The checks that were only ever running on a laptop.
+#
+# Before this file, CI ran Playwright (chromium-desktop) and the dependency audit — and nothing
+# else. `cargo test` (40 tests), the frontend vitest suite (5 files, including the offline
+# upload-queue and auth-token logic), svelte-check, and the e2e typecheck were all green on a
+# developer's machine and gated NOTHING. A check that only ever runs locally is not running.
+#
+# In .github/workflows/ because Gitea Actions scans it too (see audit.yml). Rust is installed
+# explicitly: the common Gitea runner images ship Node and Docker, not cargo.
+name: Checks
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  backend:
+    name: Backend — cargo test + clippy + fmt
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        run: |
+          if ! command -v cargo > /dev/null; then
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal
+            echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
+          fi
+          rustup component add clippy rustfmt
+
+      - uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            backend/target
+          key: cargo-${{ hashFiles('backend/Cargo.lock') }}
+          restore-keys: cargo-
+
+      # SQLx runs its queries against a live database at TEST time (see backend/tests/), so the
+      # DB-backed tests need one. The pure unit tests don't care, but starting it unconditionally
+      # keeps the job simple and honest about what it covers.
+      - name: Start Postgres
+        run: |
+          docker run -d --name ci-pg -p 5432:5432 \
+            -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=eventsnap_ci \
+            postgres:16-alpine
+          for _ in $(seq 1 30); do
+            docker exec ci-pg pg_isready -U postgres > /dev/null 2>&1 && break
+            sleep 1
+          done
+
+      - name: Test
+        working-directory: ./backend
+        env:
+          DATABASE_URL: postgres://postgres:postgres@localhost:5432/eventsnap_ci
+        # `#[sqlx::test]` creates a fresh database per test and opens its own pool; run at unbounded
+        # parallelism against a default `max_connections=100` Postgres, a full suite can exhaust the
+        # server's connection slots and fail with PoolTimedOut — a pure infra flake, not a real
+        # failure. Cap the concurrency so the gate stays trustworthy on a loaded runner.
+        run: cargo test --all-features -- --test-threads=8
+
+      - name: Clippy
+        working-directory: ./backend
+        run: cargo clippy --all-targets -- -D warnings
+
+      - name: Format
+        working-directory: ./backend
+        run: cargo fmt --check
+
+  frontend:
+    name: Frontend — vitest + svelte-check
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: 'npm'
+          cache-dependency-path: 'frontend/package-lock.json'
+
+      - name: Install deps
+        working-directory: ./frontend
+        run: npm ci || npm install
+
+      - name: Unit tests
+        working-directory: ./frontend
+        run: npm run test:unit
+
+      - name: svelte-check
+        working-directory: ./frontend
+        run: npx svelte-check --threshold error
+
+      - name: ESLint
+        working-directory: ./frontend
+        run: npm run lint
+
+      - name: Prettier
+        working-directory: ./frontend
+        run: npm run format:check
+
+  e2e-typecheck:
+    name: E2E — typecheck + lint
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+      - name: Install deps
+        working-directory: ./e2e
+        run: npm install
+      # Playwright TRANSPILES specs without typechecking them, so a type error in a spec is
+      # invisible until the assertion it guards silently does the wrong thing at runtime.
+      - name: tsc --noEmit
+        working-directory: ./e2e
+        run: npx tsc --noEmit
+
+      - name: ESLint
+        working-directory: ./e2e
+        run: npm run lint
+
+      - name: Prettier
+        working-directory: ./e2e
+        run: npm run format:check

.github/workflows/e2e.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   e2e:
-    name: Playwright E2E (chromium-desktop)
+    name: Playwright E2E (chromium + webkit)
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
@@ -25,7 +25,7 @@ jobs:
 
       - name: Install Playwright browsers
         working-directory: ./e2e
-        run: npx playwright install --with-deps chromium
+        run: npx playwright install --with-deps chromium webkit
 
       - name: Bring up the test stack
         working-directory: ./e2e
@@ -46,6 +46,30 @@ jobs:
         working-directory: ./e2e
         run: npm run test:e2e -- --project=chromium-desktop
 
+      # 09-mobile is `testIgnore`d on chromium-desktop (it needs hasTouch + a phone viewport), so
+      # running only that project left 22 tests — focus traps, touch targets, safe-area insets,
+      # viewport reflow, upload-cancel — never executing in CI. On a phone-first event app, where
+      # essentially every real guest is on a phone, that was the wrong half of the suite to skip.
+      - name: Run E2E tests (mobile)
+        working-directory: ./e2e
+        run: npm run test:e2e -- --project=chromium-mobile
+
+      # iOS Safari is the app's stated primary user (a wedding guest opening a QR link), and
+      # WebKit is the ONLY engine here that reproduces two of its behaviours:
+      #   - it enforces X-Frame-Options on the download iframe, so a site-wide `DENY` makes the
+      #     keepsake download silently do nothing. Blink hands attachments to the download
+      #     manager first and never notices. That shipped once already.
+      #   - it abandons a <video> load without a 206 response to its Range probe.
+      # Both regressions are invisible to every Chromium project, so running WebKit is what
+      # actually gates them on a PR rather than on someone remembering to test locally.
+      #
+      # The project is scoped in playwright.config.ts to the journeys a guest walks
+      # (01-auth, 02-upload, 03-feed, 06-export); four IndexedDB-blob tests skip themselves
+      # there — see helpers/webkit.ts for why that is the harness and not the app.
+      - name: Run E2E tests (webkit / iOS)
+        working-directory: ./e2e
+        run: npm run test:e2e -- --project=webkit-iphone
+
       - name: Upload Playwright report
         if: failure()
         uses: actions/upload-artifact@v4

.gitignore

@@ -1,5 +1,7 @@
 # Environment secrets — never commit the real .env
 .env
+# Stale local scratch copy of .env.example; nothing in the test stack reads it.
+.env.test
 
 # Rust
 backend/target/
@@ -11,8 +13,16 @@ frontend/build/
 frontend/export-viewer/node_modules/
 frontend/export-viewer/.svelte-kit/
 
-# Media uploads (mounted volume in production)
-media/
+# Media uploads. In production these live in the `media_data` DOCKER VOLUME, never in the
+# working tree — so this pattern is anchored to the repo root and exists only for a local
+# bind-mount experiment.
+#
+# It used to read `media/`, unanchored, which matches a directory of that name at ANY depth.
+# The only one in the repo is `e2e/fixtures/media/`, so the rule's entire practical effect was
+# to keep every E2E fixture untracked: a fresh clone got the specs and none of the images or
+# videos they read. `.github/workflows/e2e.yml` does a plain checkout and generates nothing, so
+# the committed CI job could not have run the upload, video or export suites at all.
+/media/
 
 # Playwright E2E suite — runtime artifacts (the suite itself is committed)
 e2e/node_modules/
@@ -20,11 +30,13 @@ e2e/playwright-report/
 e2e/test-results/
 e2e/.cache/
 e2e/.env.test
+# Playwright artifacts when run from the repo root instead of e2e/
+/test-results/
+/playwright-report/
 
 # OS
 .DS_Store
 Thumbs.db
 
-# Local audit/review reports — generated working artifacts, kept out of git
-docs/AUDIT-2026-06-27.md
-docs/FIX-VERIFICATION-2026-06-27.md
+# Claude Code personal (per-user) settings — shared settings.json IS committed
+.claude/settings.local.json

Caddyfile

@@ -1,29 +1,133 @@
 {$DOMAIN} {
-    encode zstd gzip
+	# Compress everything EXCEPT the SSE stream — gzip buffering delays
+	# "real-time" likes/comments until the ~30s keep-alive tick.
+	@compressible not path /api/v1/stream
+	encode @compressible zstd gzip
 
-    # SvelteKit frontend — static assets with long-lived cache (content-hashed filenames)
-    @hashed_assets path_regexp hashed /_app/immutable/.*\.[a-f0-9]{8,}\.(js|css|woff2)$
-    header @hashed_assets Cache-Control "public, max-age=31536000, immutable"
+	# Site-wide security headers (defense-in-depth). HSTS is free since Caddy
+	# already terminates TLS. nosniff also covers all of /media/*.
+	header {
+		Strict-Transport-Security "max-age=31536000; includeSubDomains"
+		X-Content-Type-Options "nosniff"
+		Referrer-Policy "strict-origin-when-cross-origin"
+	}
 
-    # API — never cache
-    @api path /api/*
-    header @api Cache-Control "no-store"
+	# X-Frame-Options: DENY everywhere EXCEPT the keepsake download endpoints, which
+	# are navigated in a HIDDEN, SAME-ORIGIN iframe so a 404/429 can't unload the PWA
+	# (see frontend/src/routes/export/+page.svelte). WebKit enforces XFO *before*
+	# honouring Content-Disposition, so a blanket DENY makes the download silently do
+	# nothing on iOS Safari — the app's primary platform. SAMEORIGIN still blocks
+	# cross-origin framing.
+	#
+	# Split into two disjoint matchers rather than an override: Caddy applies the
+	# FIRST header directive outermost, so it wins on write — a later, more specific
+	# `header` would be silently ignored.
+	@framable path /api/v1/export/zip /api/v1/export/html
+	@not_framable not path /api/v1/export/zip /api/v1/export/html
+	header @framable X-Frame-Options "SAMEORIGIN"
+	header @not_framable X-Frame-Options "DENY"
 
-    # Media is served by the authenticated gateway at /media/{kind}/{id}, which
-    # sets its own Cache-Control (private) and security headers per response — no
-    # Caddy-side cache rules (the old /media/previews|originals matchers were for
-    # the retired static mount).
+	# SvelteKit frontend — static assets with long-lived cache (content-hashed filenames)
+	@hashed_assets path_regexp hashed /_app/immutable/.*\.[a-f0-9]{8,}\.(js|css|woff2)$
+	header @hashed_assets Cache-Control "public, max-age=31536000, immutable"
 
-    # Route API and media requests to the Rust backend. Set X-Real-IP from the
-    # real TCP peer and overwrite any client-supplied value so the backend's
-    # rate-limit keys can't be spoofed via a forged X-Forwarded-For.
-    reverse_proxy /api/* app:3000 {
-        header_up X-Real-IP {remote_host}
-    }
-    reverse_proxy /media/* app:3000 {
-        header_up X-Real-IP {remote_host}
-    }
+	# Preview/thumbnail/display images. These are served by the app through a
+	# visibility-checked alias (/api/v1/upload/{id}/{preview,thumbnail,display}) so
+	# moderation can revoke access; the app serves no /media route at all, so there is no
+	# direct path to the bytes. Privately cacheable for a short window (the app sets the
+	# same header; this is the edge carve-out from the blanket no-store below). Kept short
+	# so a moderated image stops being served to a direct-URL holder promptly.
+	#
+	# `display` was missing here while the backend set `private, max-age=300` on it, and
+	# because `header` REPLACES, the blanket no-store below silently won. That route is the
+	# ~2048px derivative the diashow uses exclusively, so a projector left running all
+	# evening re-fetched a full-size JPEG for every slide — roughly 2-4 GB pulled through
+	# the app over 8 hours, on the same venue uplink 100 guests are uploading over, and a
+	# blank frame on every network hiccup.
+	@media_api path /api/v1/upload/*/preview /api/v1/upload/*/thumbnail /api/v1/upload/*/display
+	header @media_api Cache-Control "private, max-age=300"
 
-    # Everything else goes to SvelteKit frontend
-    reverse_proxy frontend:3001
+	# API and health — never cache, EXCEPT the gated image routes above. A cached health
+	# response would report the last known state rather than the current one.
+	@api {
+		path /api/* /health
+		not path /api/v1/upload/*/preview /api/v1/upload/*/thumbnail /api/v1/upload/*/display
+	}
+	header @api Cache-Control "no-store"
+
+	# Route API and media requests to the Rust backend.
+	#
+	# The app serves no /media route at all (see the note in backend/src/main.rs) — media
+	# bytes are reachable only through the visibility-checked /api/v1/upload aliases, so
+	# /media/* forwards to a plain 404. The proxy line is kept deliberately: it means the
+	# edge faithfully hands /media to the app, so if a future change ever re-introduces a
+	# static media route the e2e gating specs see it here exactly as production would,
+	# instead of being masked by the SvelteKit 404 page.
+	reverse_proxy /api/* app:3000
+	reverse_proxy /media/* app:3000
+
+	# The backend registers /health on its ROOT router, not under /api/v1, so it needs its
+	# own line — without it the catch-all below hands /health to SvelteKit, which has no
+	# such route and returns its 404 page. That made the documented post-deploy check
+	# (`curl -fsS https://DOMAIN/health`) fail 100% of the time on a perfectly healthy
+	# stack. e2e/Caddyfile.test has always carried this line; production never did.
+	reverse_proxy /health app:3000
+
+	# Everything else goes to SvelteKit frontend
+	reverse_proxy frontend:3001
+
+	# Last-resort page for when Caddy itself cannot reach an upstream — the app or frontend
+	# container down, restarting, or still warming up after a host reboot. Without it a guest
+	# gets Caddy's bodiless 502: a completely blank page, which reads as "the whole thing is
+	# gone" rather than "try again in a moment".
+	#
+	# THIS DOES NOT TOUCH APPLICATION ERRORS. `handle_errors` fires only on errors CADDY
+	# generates; a status the app returns through `reverse_proxy` is written back verbatim and
+	# never reaches here. That distinction is load-bearing rather than incidental: the keepsake
+	# download navigates a HIDDEN IFRAME and depends on a real 404/429 arriving from the app
+	# (frontend/src/routes/export/+page.svelte), and every API route answers 403/404/429 as
+	# ordinary JSON that the client parses. Swallowing those into an HTML page would be a far
+	# worse regression than the blank 502 this fixes. Verified against this exact config: an
+	# upstream 404 through `reverse_proxy` still arrives as `Content-Type: application/json`
+	# with its body intact, while only a dial failure renders the page below.
+	#
+	# Scoped to 5xx so a hypothetical future Caddy-generated 4xx (there is none today) still
+	# returns plainly instead of claiming the server is restarting.
+	#
+	# The body is inline because the caddy service mounts ONLY ./Caddyfile and caddy_data —
+	# there is no volume to ship an HTML file through and the image has no build step, so a
+	# static file would mean changing the deployed stack's compose definition. No external
+	# font, stylesheet or image is referenced: the app may be exactly what is down.
+	#
+	# `handle_errors` has NO position in the directive order — Caddy hoists it into a separate
+	# `errors` route list — so it cannot disturb the "first `header` directive wins" hazard
+	# documented at the top of this file. The site-wide security headers still apply to it.
+	handle_errors 5xx {
+		header Content-Type "text/html; charset=utf-8"
+		header Cache-Control "no-store"
+		# {err.status_code} preserves the real status. Hardcoding 503 would mislabel a genuine
+		# 502 for anything watching from outside.
+		respond `<!doctype html>
+<html lang="de">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>Gleich zurück</title>
+<style>
+html{background:#faf9f7;color:#1a1918;font-family:system-ui,-apple-system,"Segoe UI",Roboto,sans-serif}
+body{margin:0;min-height:100vh;display:flex;align-items:center;justify-content:center;padding:2rem;text-align:center}
+h1{font-family:Georgia,"Times New Roman",serif;font-weight:600;font-size:1.5rem;margin:0 0 .75rem}
+p{margin:0;color:#545350;line-height:1.5}
+@media (prefers-color-scheme:dark){html{background:#100f0f;color:#f5f4f2}p{color:#a6a4a1}}
+</style>
+</head>
+<body>
+<main>
+<h1>Wir sind gleich zurück</h1>
+<p>Die Seite wird gerade neu gestartet.<br>Bitte lade in einem Moment neu — deine Fotos bleiben gespeichert.</p>
+</main>
+</body>
+</html>
+` {err.status_code}
+	}
 }

DEPLOYMENT_RUNBOOK.md

@@ -0,0 +1,693 @@
+# EventSnap — Production Deployment Runbook
+
+Target: **Hetzner CX22** (2 vCPU, 4 GB RAM, 40 GB disk), single host, docker compose.
+Event profile: ~100 guests, ~100 photos + a few videos, one evening, **operator attending and unavailable to troubleshoot**.
+
+Everything here is written for that last constraint. Where a choice trades throughput for
+"cannot need attention on the night", it takes the stable option.
+
+> **Note on this repo's own docs.** `README.md:62` and `PROJECT.md:359` specify a **CX33
+> (4 vCPU / 8 GB / 80 GB)**. You are deploying to half of that on every axis. Two pieces of
+> tuning advice in `.env.example` are calibrated for the CX33 and are actively wrong for a
+> CX22 — they are called out in §3. Trust this file over `.env.example` for sizing.
+
+---
+
+## 0. Timeline — the single most important control
+
+### Step zero: commit everything, before you build anything
+
+**The production deployment does not exist in git yet.** At the time of writing, `docker-compose.yml`
+and `.env.example` are modified but uncommitted, and `DEPLOYMENT_RUNBOOK.md`,
+`docker-compose.build.yml`, both `.dockerignore` files and migrations `021`/`022` are untracked.
+None of them is gitignored — they are simply not committed.
+
+That is not a tidiness problem, it is the deployment failing in two ways at once:
+
+- §7 tells you to `git clone` onto the server. `git show HEAD:docker-compose.yml` still has
+  `build:` keys and **no `image:` keys**, so on that clone `docker compose pull` skips both services
+  and `docker compose up -d` starts **a fat-LTO release build of 427 crates on the CX22** — the
+  exact scenario §1 rules out as an expected OOM. The committed file also has no log rotation.
+- `sqlx::migrate!()` embeds `./migrations` **at compile time**. A build from the working tree bakes
+  in 021 and 022 and applies them on first boot; any later rebuild from a clean clone produces an
+  image that lacks them and crash-loops with `VersionMissing` against its own database.
+
+```bash
+git add docker-compose.yml docker-compose.dev.yml docker-compose.build.yml .env.example \
+        backend/.dockerignore frontend/.dockerignore frontend/Dockerfile \
+        backend/migrations/021_*.sql backend/migrations/022_*.sql \
+        DEPLOYMENT_RUNBOOK.md
+git commit -m "chore: production compose, ignore files and runbook"
+git push
+
+# Prove it landed — this must print two `image:` lines and nothing about `build:`
+git show HEAD:docker-compose.yml | grep -E 'image:|build:'
+git show HEAD --stat | grep -c migrations/02   # must be 4
+```
+
+| When | What |
+|---|---|
+| **T‑7 days** | Commit and push everything above. Registry + DNS pre-flight (§5). Build and push images (§6). |
+| **T‑5 days** | First deploy to the server (§7). Verify admin login. Leave it running. |
+| **T‑3 days** | **Freeze migrations.** No further code deploys unless something is broken. |
+| **T‑2 days** | Pre-pull current *and* previous image tags (§9). Run the backup rehearsal (§10). |
+| **Event day** | Change nothing. Configuration tweaks via the admin dashboard only (§4). |
+
+**Why the freeze matters more than anything else here.** Migrations run automatically at boot
+(`backend/src/db.rs`, `create_pool`) and `sqlx::migrate!()` is used *without* `set_ignore_missing`. An older
+image booted against a newer schema does not degrade — it **crash-loops** with `VersionMissing`.
+The repo documents this itself in `backend/migrations/014_export_epoch.up.sql:3-8`. Once the
+migration set is frozen, rollback is a one-line `.env` edit; before it is frozen, rollback means
+hand-running down-SQL under pressure.
+
+---
+
+## 1. Deployment strategy — build on the Mac, push, pull
+
+**Decision: build `linux/amd64` images on the M3 Pro, push to `registry.mc02.dev`, pull on the server.**
+
+Rejected alternatives, with the reason each loses:
+
+| Option | Why not |
+|---|---|
+| **Build on the CX22** | `backend/Cargo.toml` sets `lto = true` + `codegen-units = 1` over **427 crates**. Fat LTO links the whole program in one single-threaded process; peak RSS is estimated at 2.5–4 GB against ~1.5–2.5 GB free with the stack running. OOM is the expected outcome, not a tail risk. And *rollback would also be a build* — 35–60 min under pressure. |
+| **CI (Gitea on Pi 5)** | Ruled out by you, and correct: a Pi 5 is strictly worse than the CX22 for a fat-LTO link. |
+| **True cross-compilation** (`--target x86_64-unknown-linux-musl`) | The dependency graph has **four C-compiling crates** — `ring` (per-arch assembly), `zstd-sys`, `libdeflate-sys`, `libsqlite3-sys` — so it needs a real musl cross-toolchain. Alpine has no such package for an arm64 host; the working answer is `cargo-zigbuild`, which means a new base image and a new toolchain days before an unrepeatable event. **Slow but certain beats fast but novel.** |
+
+Emulated build is the right call because the cost lands where it is free: on your laptop, days
+early, with nothing depending on it. Estimated wall-clock for the backend is **25–60 min with
+Rosetta enabled** (hours without it) — start it and walk away.
+
+> **Escape hatch if emulation is unbearable:** spin up a temporary Hetzner CPX41 (8 vCPU/16 GB) in
+> the same account, build natively, push, destroy it. Costs cents, same commands, no repo change.
+
+---
+
+## 2. Repo changes — ALREADY APPLIED
+
+> **Status: these are done, in the working tree.** They are documented here so you know what
+> changed and why, not as work to repeat. Run `git diff` to review before committing.
+
+### 2.1 `.dockerignore` files (were absent)
+
+`backend/.dockerignore`:
+```
+target/
+```
+
+`frontend/.dockerignore`:
+```
+node_modules/
+.svelte-kit/
+build/
+```
+
+Without these, the first time you run `cargo build` or `npm install` locally, every image build
+ships a multi-GB context to an *emulated* builder. Worse: `frontend/Dockerfile:9` does `COPY . .`
+**after** `npm ci`, so a macOS `node_modules/` would be merged over the container's Linux one.
+
+### 2.2 Switch compose from `build:` to `image:`
+
+In `docker-compose.yml`, replace the `build:` block on `app` and `frontend`:
+
+```yaml
+  app:
+    image: registry.mc02.dev/eventsnap/app:${EVENTSNAP_VERSION:?set EVENTSNAP_VERSION in .env}
+```
+```yaml
+  frontend:
+    image: registry.mc02.dev/eventsnap/frontend:${EVENTSNAP_VERSION:?set EVENTSNAP_VERSION in .env}
+```
+
+Two deliberate properties:
+- The `:?` form **fails loudly** on an unset variable instead of resolving to an empty tag.
+- **Removing `build:` entirely is a safety feature.** With no `build:` key on the server, a wrong
+  tag is an instant `manifest unknown` — never a surprise 45-minute compile on the production box.
+
+New `docker-compose.build.yml` (opt-in, Mac only — follows the convention stated in
+the header of `docker-compose.dev.yml` that overlays are never auto-loaded):
+
+```yaml
+# Build overlay. NOT loaded automatically. Used only where images are BUILT — never on the
+# production server, which pulls.
+#   docker compose -f docker-compose.yml -f docker-compose.build.yml build
+services:
+  app:
+    build: { context: ./backend, dockerfile: Dockerfile }
+  frontend:
+    build: { context: ./frontend, dockerfile: Dockerfile }
+```
+
+`e2e/docker-compose.test.yml` keeps its own `build:` blocks, so the e2e gate is unaffected.
+
+### 2.3 Add log rotation to every service
+
+`docker-compose.yml` currently sets **no logging config**, so the default `json-file` driver keeps
+logs forever, on the same filesystem as Postgres and the media. Add to each of the four services:
+
+```yaml
+    logging:
+      driver: json-file
+      options: { max-size: "10m", max-file: "3" }
+```
+
+(Equivalently, set it once in `/etc/docker/daemon.json` — but that restarts the Docker daemon,
+so do it *before* the stack is live, not after.)
+
+---
+
+## 3. `.env` — production values
+
+```bash
+# ── Identity ──────────────────────────────────────────────────────────────
+DOMAIN=<your domain>
+EVENT_NAME=<...>
+EVENT_SLUG=<...>
+
+# ── Image version (NEW — drives the image: tags in docker-compose.yml) ────
+EVENTSNAP_VERSION=v0.13.0
+
+# ── Secrets — ALL of them, before the first `up -d` ───────────────────────
+JWT_SECRET=<openssl rand -hex 64>
+POSTGRES_PASSWORD=<openssl rand -hex 24>
+DATABASE_URL=postgres://eventsnap:<SAME PASSWORD>@db:5432/eventsnap
+ADMIN_PASSWORD_HASH='<docker run --rm caddy:2-alpine caddy hash-password --plaintext "pw">'
+
+# ── Paths — must match the volume mounts ──────────────────────────────────
+MEDIA_PATH=/media          # pinned by compose anyway, but keep consistent
+EXPORT_PATH=/exports       # NOT pinned by compose — see the trap in §7.3
+
+# ── Sizing (see the two corrections below) ────────────────────────────────
+DATABASE_MAX_CONNECTIONS=30
+COMPRESSION_WORKER_CONCURRENCY=2
+
+# ── Comments off, likes + captions on ─────────────────────────────────────
+COMMENTS_ENABLED=false
+
+# ── Logging (NEW — production currently defaults to DEBUG) ────────────────
+RUST_LOG=eventsnap_backend=info,tower_http=warn
+```
+
+### Two corrections to the repo's own advice — do not follow `.env.example` here
+
+**`COMPRESSION_WORKER_CONCURRENCY`: keep `2`. Do NOT raise to 4, and do NOT raise the app memory
+limit to 2G.** `.env.example:92-98` justifies both on the premise that "each worker can run an
+ffmpeg transcode". **There is no transcode anywhere in this codebase.** `services/video.rs::run_ffmpeg`
+runs `ffmpeg -ss <t> -i <src> -vframes 1 -vf scale=…` — a single poster frame. Video originals are
+stored and served byte-for-byte.
+
+The real memory consumer is the **image** path: `image` 0.25's `resize` builds an `Rgba32F`
+intermediate at **16 bytes/px**, sized `source_width × target_height`, which the 256 MiB decode
+guard in `imaging::decode_limits` does not cover. Estimated peak per photo:
+
+| Source | Peak (decode + display resize) |
+|---|---|
+| 12 MP (typical phone) | ~145 MB |
+| 24 MP (iPhone Pro default) | ~223 MB |
+| 48 MP ("Max" mode) | ~354 MB |
+
+At concurrency 2, two 48 MP photos ≈ 800 MB against the 1 GiB cap — ~25% margin. At concurrency 4
+the same pair is ~1.5 GB → **OOM**. And app=2G + db=1G + 256M + 256M + ~370 MB OS/Docker ≈ 3954 MiB
+against ~3910 MiB MemTotal — the box is oversubscribed before a single photo arrives.
+
+**`quota_tolerance`: keep `0.75`. Raising it does not make anything more generous for a real guest.**
+See §4.
+
+---
+
+## 4. Admin dashboard configuration
+
+These live in the DB `config` table, not `.env`. Changes take effect on the **next request** —
+`patch_config` invalidates the cache synchronously (`admin::patch_config`). No restart needed. Set them
+after the first deploy, before the event.
+
+| Key | Default | **Set to** | Why |
+|---|---|---|---|
+| `upload_rate_per_hour` | 100 | **1000** | A guest multi-selecting 100 photos hits exactly 100. Client backs off and resumes, but this makes it a non-issue. |
+| `feed_rate_per_min` | 60 | **240** | Headroom for reconnect bursts. |
+| `social_rate_per_min` | 120 | **600** | This is the **likes** limiter — the interaction you're keeping. |
+| `export_rate_per_day` | 3 | **20** | **One shared bucket across both archives** — `enforce_export_rate` keys on `export:{user_id}` regardless of which archive is being fetched. Downloading Gallery.zip + Memories.zip costs 2 of 3; one retry locks a guest out for 24 h. The limit is now charged when the download *ticket* is minted, so being over it produces a visible German error instead of a tap that silently does nothing. |
+| `max_video_size_mb` | 500 | **leave at 500** | See below. |
+| `quota_tolerance` | 0.75 | **leave at 0.75** | See below. |
+| `quota_enabled`, `storage_quota_enabled`, `rate_limits_enabled` | true | **leave on** | This is the only disk-full safety net. |
+
+**Ignore `estimated_guest_count` and `upload_count_quota_enabled`.** Both are seeded, validated and
+rendered in the admin UI — and **read by no code at all** (verified by grep across `backend/src`).
+Changing them does nothing. `estimated_guest_count` in particular does *not* feed the quota formula.
+
+### Why quotas are already as generous as you want
+
+```
+per_user_limit = floor(free_disk × quota_tolerance / max(active_uploaders, 1))
+```
+`active_uploaders` is `SELECT COUNT(DISTINCT user_id) FROM upload WHERE deleted_at IS NULL`
+(`upload::compute_storage_quota`) — **people who actually uploaded**, not guests who joined. The 70 guests who never
+upload are not in the denominator; their share flows to the photographers automatically. **The
+redistribution you asked for is already the design.**
+
+With ~28 GB free and a realistic 30 people actually uploading, each gets **~700 MB** — against an
+expected ~1.25 GB for the *entire event*. Nobody will be blocked.
+
+Raising `quota_tolerance` would only raise the **saturation ceiling** (media converges to
+`t/(1+t)` of free space: 43% at 0.75, 50% at 1.0). It does nothing for a real guest at your volume,
+and it eats the headroom the keepsake needs — the export preflight reserves `media × 1.10 × 2`
+because `Gallery.zip` and `Memories.zip` each store media **uncompressed** (`export.rs` — both archives store media uncompressed).
+
+**Why `max_video_size_mb` stays at 500.** An earlier draft of this runbook said to lower it to 250,
+on the grounds that there is no client-side size check. That was wrong on both halves:
+
+- A client guard **does** exist — `frontend/src/routes/upload/+page.svelte` rejects anything over
+  `HARD_MAX_UPLOAD_BYTES` (576 MiB) before a byte leaves the phone, alongside the HEIC reject.
+- That guard is a **compile-time constant**, not the DB value. Lowering `max_video_size_mb` therefore
+  changes nothing on the client: the picker still accepts the clip, the phone still starts sending
+  it, and the *server* aborts it partway (`stream_field_to_file` does stop at the cap, so the AP is
+  not saturated for the full file — but the guest still gets a mid-upload failure where 500 MB would
+  simply have worked).
+
+So lowering it is a pure capacity decision with no UX upside, and at your volume there is no capacity
+problem to solve. Leave it. If you ever do want a smaller ceiling to bite on the phone, the constant
+above has to move with it.
+
+---
+
+## 5. Pre-flight — T‑7 days (do NOT leave this to event week)
+
+### Registry
+
+From **both** the Mac and the server, as **the user who will deploy** (root's `docker login` does
+not help a non-root deploy — credentials go to `~/.docker/config.json`):
+
+```bash
+getent hosts registry.mc02.dev                 # DNS resolves from the server
+curl -fsSI https://registry.mc02.dev/v2/       # TLS must be PUBLICLY trusted; Docker rejects
+                                               # self-signed without extra daemon config
+docker login registry.mc02.dev
+```
+
+Also confirm: the `eventsnap` repository/namespace exists if your registry requires pre-creation
+(Harbor does; plain `registry:2` does not), and the registry host has ~500 MB free per release.
+
+### DNS and TLS — get this wrong and you are locked out for an hour
+
+The DNS **A record must point at the CX22 before the first `docker compose up -d`**, because Caddy
+attempts certificate issuance on boot. Let's Encrypt allows only **5 failed validations per hostname
+per hour** (refilling 1 per 12 min). A misconfigured DNS record plus a few impatient restarts will
+rate-limit you out of getting a certificate at all.
+
+- Deploy days early so issuance happens with no time pressure.
+- **Never delete the `caddy_data` volume** — it holds the certificate and the ACME account key.
+- Never run `docker compose down -v`. It destroys `postgres_data`, `media_data`, `exports_data`
+  *and* `caddy_data`.
+
+### Host preparation
+
+```bash
+docker compose version          # must be v2.x — the deploy.resources limits need it
+free -h && swapon --show        # Hetzner images ship no swap
+df -h /var/lib/docker           # want ≥ 25 GB free
+```
+
+**Add 2 GB of swap** as an OOM cushion — a compression spike that would otherwise kill the container
+instead swaps out cold pages and merely runs slowly:
+
+```bash
+fallocate -l 2G /swapfile && chmod 600 /swapfile && mkswap /swapfile && swapon /swapfile
+echo '/swapfile none swap sw 0 0' >> /etc/fstab
+sysctl -w vm.swappiness=10 && echo 'vm.swappiness=10' > /etc/sysctl.d/99-swap.conf
+```
+
+> **Gotcha:** Compose sets each container's `Memory` limit but leaves `MemorySwap` unset, and Docker
+> then allows swap equal to the memory limit — so adding host swap silently **doubles** every
+> container ceiling. If you add swap, also add `memswap_limit: 1152m` to `app` and `db`, and
+> `memswap_limit: 320m` to `frontend` and `caddy` (service-level, not under `deploy:`).
+
+---
+
+## 6. Build and push — on the Mac
+
+Enable **Docker Desktop → Settings → General → "Use Rosetta for x86_64/amd64 emulation"**, and set
+**Resources → Memory ≥ 8 GB** (the fat-LTO step will OOM inside the VM otherwise, even with 18 GB on
+the host).
+
+```bash
+docker run --rm --platform linux/amd64 alpine uname -m     # must print x86_64
+
+cd /Users/fabianhammprivat/Projects/EventSnap
+VERSION=v0.13.0                          # latest existing tag is v0.12.0 — see §9 before reusing it
+ROLLBACK=v0.13.0-a                       # the SAME source, tagged twice; §9 explains why
+SHA=$(git rev-parse --short HEAD)
+
+docker buildx create --name eventsnap --use 2>/dev/null || docker buildx use eventsnap
+
+docker buildx build --platform linux/amd64 \
+  -t registry.mc02.dev/eventsnap/app:$VERSION \
+  -t registry.mc02.dev/eventsnap/app:$ROLLBACK \
+  -t registry.mc02.dev/eventsnap/app:$SHA \
+  --push ./backend
+
+docker buildx build --platform linux/amd64 \
+  -t registry.mc02.dev/eventsnap/frontend:$VERSION \
+  -t registry.mc02.dev/eventsnap/frontend:$ROLLBACK \
+  -t registry.mc02.dev/eventsnap/frontend:$SHA \
+  --push ./frontend
+```
+
+### Verify the architecture — never skip this
+
+An arm64 image pulls fine and then dies with `exec format error`. Catch it here, not on the server:
+
+```bash
+docker buildx imagetools inspect registry.mc02.dev/eventsnap/app:$VERSION
+docker buildx imagetools inspect registry.mc02.dev/eventsnap/frontend:$VERSION
+# Both MUST report  Platform: linux/amd64
+```
+
+Then prove the binary actually executes. `AppConfig::from_env()` runs before any DB connection
+(`main.rs` builds `AppConfig` before touching the pool), so this needs no database:
+
+```bash
+docker run --rm --platform linux/amd64 \
+  -e APP_ENV=production -e JWT_SECRET=x -e DATABASE_URL=x -e EVENT_SLUG=x \
+  registry.mc02.dev/eventsnap/app:$VERSION
+```
+Expect the "Refusing to start in production … placeholder" message. **That message means the amd64
+binary ran.** `exec format error` means the architecture is wrong.
+
+**Tag policy: never `latest` in production.** With `latest` you cannot tell what is running,
+rollback becomes a registry re-push (impossible if the registry is down — exactly when you need it),
+and `restart: unless-stopped` after a reboot is ambiguous. Two immutable tags per build: semver and
+short SHA. Deploy by semver.
+
+---
+
+## 7. First deploy — on the server
+
+```bash
+# Directory name matters: volumes are prefixed with it, and README's backup commands
+# hardcode the `eventsnap_` prefix.
+git clone <repo> eventsnap && cd eventsnap
+cp .env.example .env && nano .env          # every value from §3
+docker login registry.mc02.dev
+docker compose pull                        # must fully succeed before anything starts
+```
+
+### 7.1 The secret pre-flight — run this before the first `up -d`, always
+
+```bash
+docker compose run --rm --no-deps app
+```
+
+`--no-deps` means `db` never starts, so **no Postgres data directory is initialised**.
+`AppConfig::from_env()` runs first and reports *every* placeholder at once (`config::validate_secrets`).
+When the only remaining complaint is a database *connection* failure, the secrets are good.
+
+**Why this step exists.** `POSTGRES_PASSWORD` is applied **only at initdb**. `docker-compose.yml`
+starts `db` in the same command as `app`, so a single `up -d` with a placeholder bakes the wrong
+password in permanently — the app then loops on `password authentication failed`, and the only exits
+are `ALTER ROLE` or `down -v`, which deletes the database, the media and the exports. The repo
+describes this trap at `backend/src/db.rs` (`explain_auth_failure`); this command is what avoids it.
+
+### 7.2 Bring it up
+
+```bash
+# `.env` is consumed by docker compose, not by your shell — load it before using $DOMAIN.
+set -a; . ./.env; set +a
+
+docker compose up -d
+docker compose logs -f app          # wait for "database connected and migrations applied"
+curl -fsS https://$DOMAIN/health    # → ok  (503 means the app is up but the DB is not)
+```
+
+### 7.3 Verify the three things compose does *not* pin
+
+`MEDIA_PATH` is pinned to `/media` on the `app` service in `docker-compose.yml`. Its siblings
+are not:
+
+```bash
+docker compose exec app printenv DATABASE_URL EXPORT_PATH ADMIN_PASSWORD_HASH
+```
+
+1. **`DATABASE_URL`** must contain `@db:5432`. A dev `.env` points it at `@localhost`, which inside
+   the container is the app itself.
+2. **`EXPORT_PATH`** must be `/exports`. Anywhere else and the keepsake archives are written to the
+   container's writable layer and **vanish on the next `up -d`** — including on a rollback.
+3. **`ADMIN_PASSWORD_HASH`** must match `.env` **byte for byte.**
+
+**Then actually log in to `/admin` with the real password.** This is not optional politeness:
+
+- The production secret guard only rejects *placeholders* (`config::looks_placeholder`). A hash **corrupted**
+  by shell or Compose escaping is not a placeholder — the app boots green, `/health` says `ok`, and
+  every admin login 401s.
+- The Admin user row is created **by a successful admin login** (`auth::handlers::admin_login`), and
+  promoting anyone to Host requires an Admin or Host (`auth::middleware`'s role guard). **No admin login
+  ⇒ no host, ever** ⇒ you cannot close the event, release the gallery, ban anyone, reset a PIN, or
+  change any limit — for the whole event.
+
+Per the Compose spec, single-quoted `env_file` values *are* used literally and the quotes are
+stripped, so the single-quote form in `.env.example` is correct. The comment in
+`docker-compose.dev.yml` claiming production has the same bug is **stale**. Verify anyway —
+the cost of checking is 10 seconds; the cost of being wrong is the whole event.
+
+**Promote a second person to Host** once you are in, so a single lost session is not fatal.
+
+---
+
+## 8. Post-deploy verification
+
+```bash
+set -a; . ./.env; set +a                                     # $DOMAIN comes from .env, not your shell
+
+docker compose ps                                            # all four healthy
+docker inspect -f '{{.HostConfig.Memory}}' eventsnap-app-1   # must be 1073741824, not 0
+curl -fsS https://$DOMAIN/health                             # ok — now a real DB check, not a constant
+docker compose exec app printenv COMMENTS_ENABLED RUST_LOG
+docker builder prune -af && docker image prune -f            # reclaim build cache
+df -h /var/lib/docker
+```
+
+Then, from a phone on cellular (not the office wifi):
+
+- [ ] Join as a guest with a PIN
+- [ ] Upload a photo → appears in the feed within a few seconds
+- [ ] Upload a video → plays back (iOS Safari range requests)
+- [ ] Add a caption, add a like — **no comment UI anywhere**
+- [ ] Admin login works; host dashboard reachable
+- [ ] Release the gallery on a test event and download both archives
+
+---
+
+## 9. Rollback
+
+### There is no older image you can roll back to. Build the rollback target yourself.
+
+Read this before the event, not during it. The obvious move — drop `EVENTSNAP_VERSION` back to the
+previous released tag — **takes the app down permanently** and looks like a crash loop with no
+explanation:
+
+```
+$ git ls-tree --name-only v0.12.0 backend/migrations/ | wc -l
+12          # 6 migrations. HEAD has 22.
+$ git rev-list --count v0.12.0..HEAD
+154
+```
+
+`db.rs` runs `sqlx::migrate!()` with no `set_ignore_missing`, so an image built from a 6-migration
+tree, booting against a database that already carries versions 007–022, returns `VersionMissing`.
+`create_pool` errors, `main` exits 1, and `restart: unless-stopped` restarts it forever — with Caddy
+still routing traffic to it. (`014_export_epoch.up.sql` documents this failure mode; §0 restates it.)
+No `v0.12.0` image was ever built or pushed either, so the pre-pull would fail with
+`manifest unknown` before you ever got that far.
+
+**So: at build time, tag the SAME frozen commit twice.** Two identical images, two names. The
+rollback then swaps to a binary that is bit-for-bit what you tested and carries the identical
+migration set, which makes it a genuine no-op rather than a gamble:
+
+```bash
+# In §6, push both tags from the one build:
+VERSION=v0.13.0
+ROLLBACK=v0.13.0-a          # same source, different name — the rollback target
+
+docker buildx build --platform linux/amd64 \
+  -t registry.mc02.dev/eventsnap/app:$VERSION \
+  -t registry.mc02.dev/eventsnap/app:$ROLLBACK \
+  --push ./backend
+# ...and the same two tags for ./frontend
+```
+
+**Rolling back — ~30 seconds, no network:**
+
+```bash
+sed -i 's/^EVENTSNAP_VERSION=.*/EVENTSNAP_VERSION=v0.13.0-a/' .env
+docker compose up -d app frontend
+```
+
+This only works offline if both are already resident. **Pre-pull all four at T‑2:**
+
+```bash
+docker pull registry.mc02.dev/eventsnap/app:v0.13.0
+docker pull registry.mc02.dev/eventsnap/frontend:v0.13.0
+docker pull registry.mc02.dev/eventsnap/app:v0.13.0-a
+docker pull registry.mc02.dev/eventsnap/frontend:v0.13.0-a
+docker image ls | grep eventsnap        # confirm all four
+```
+
+Once resident, `up -d`, reboots, restarts and rollbacks need **zero** registry contact. That single
+step makes a registry outage on event day irrelevant.
+
+Be clear-eyed about what this buys you: an identical image cannot undo a bad *release*, only an
+image that got corrupted or a container that wedged — and `docker compose restart app` already
+covers both. It exists so that the rollback line in the emergency card is safe to run rather than
+catastrophic. **If you genuinely need to undo a code change during the event, you cannot; freeze
+early enough that you never have to.**
+
+**Across a migration boundary — avoid by freezing.** If you must: all 22 migrations have paired
+`.down.sql` files, but **none of them removes its own `_sqlx_migrations` row**, so that second step
+is mandatory and undocumented:
+
+```bash
+docker compose stop app
+# `sh -c` so the CONTAINER expands the credentials. They live in the container's environment
+# and in .env — not in your shell — so an unwrapped `-U "$POSTGRES_USER"` sends `-U ""` and
+# psql answers `FATAL: role "" does not exist`.
+docker compose exec -T db sh -c \
+  'psql -U "$POSTGRES_USER" -d "$POSTGRES_DB" -v ON_ERROR_STOP=1' \
+  < backend/migrations/0NN_x.down.sql
+docker compose exec -T db sh -c \
+  'psql -U "$POSTGRES_USER" -d "$POSTGRES_DB" -c "DELETE FROM _sqlx_migrations WHERE version = NN;"'
+```
+
+Migration **014** is the only destructive one on the way up, and the only one with a rehearsal
+harness — `backend/scripts/rehearse-014.sh`. Run it once against a real dump before the event.
+
+**Registry-down transport fallback** (layers are already compressed — do not add gzip):
+
+```bash
+docker save registry.mc02.dev/eventsnap/app:v0.13.0 \
+            registry.mc02.dev/eventsnap/frontend:v0.13.0 | ssh root@SERVER 'docker load'
+```
+
+---
+
+## 10. Backup
+
+Full commands are in `README.md:315-435` and are correct — `pg_dump --clean --if-exists`, plus
+`alpine tar` out of `eventsnap_media_data` and `eventsnap_exports_data`, mounted at `/src` (not
+`/media`), with `chown -R 100:101` on restore because the app runs non-root and BusyBox tar has no
+`--same-owner`. There is deliberately no script.
+
+Two gaps the README does not cover:
+
+1. **Nothing backs up `.env`**, which holds the only copy of `POSTGRES_PASSWORD`. A dump you cannot
+   authenticate against is not a backup. Copy `.env` off the box, encrypted, once it is final.
+2. **Timing.** Do not use nightly cron — every irreplaceable byte is created inside one evening.
+   Take the dump and the media tarball back-to-back **the night of the event, after locking uploads
+   from the host dashboard**, so the pair is consistent.
+
+---
+
+## 11. Disk — the numbers for 40 GB
+
+Expected event (100 photos @ ~4 MB, 5 videos @ ~150 MB). Originals are **always kept** and never
+lossily recompressed; derivatives are a ≤800 px preview and a ≤2048 px display JPEG.
+
+```
+media (originals + derivatives)                    ~1.25 GB
+peak during keepsake build (+ Gallery + Memories)  ~3.5 GB
+OS + Docker images + Postgres + logs               ~4.5 GB
+────────────────────────────────────────────────────────────
+total                             ~11–13 GB of ~36 GB usable
+```
+
+**40 GB fits with roughly 3× headroom**, provided you build elsewhere (a server-side build adds
+3–5 GB of cache that permanently shrinks the guest quota, because the quota is recomputed against
+*live* free space on every upload).
+
+The `README.md:295-299` "ENOSPC" projection models guests **saturating the quota** (~12 GB of
+media), not 100 photos. That scenario needs ~10× your expected volume — and it degrades gracefully:
+the export preflight refuses up front rather than hitting ENOSPC mid-write, and the host dashboard
+warns when free space drops below 10 GB or below the keepsake requirement (`handlers::host`'s low-disk thresholds).
+
+---
+
+## 12. Known issues you are shipping with
+
+None of these has a fix in this runbook; they are listed so nothing is a surprise. Severity is
+scored purely by "would this interrupt you during the event".
+
+### Fixed in this pass
+
+| Was | Fix |
+|---|---|
+| **Queued uploads never rehydrated** — `loadQueue()` had one call site, so a guest whose PWA was evicted mid-upload and reopened onto `/feed` had pending photos in IndexedDB that nothing ever read. Silent photo loss. | `loadQueue()` now runs on every authenticated boot in `+layout.svelte`. |
+| **A corrupted `ADMIN_PASSWORD_HASH` booted green** and only failed at admin login — unrecoverable mid-event. | `config.rs` now validates the bcrypt *shape*, not just placeholder-ness, and refuses to start. |
+| **SSE reconnect thundering herd** — flat 500 ms jitter regardless of backoff. | Jitter now scales with the delay; the feed's in-place refresh is spread over 800–2800 ms. |
+| **No client-side size/HEIC pre-check** — a doomed 600 MB upload saturated the venue AP before being rejected. | Certain-rejects are refused before any bytes leave the phone. |
+| **Upload-queue UI unreachable** — the badged FAB opened the picker, not the queue, so a failed upload had no retry button. | The upload sheet now shows a queue entry whenever the badge is non-zero. |
+| **A mid-event 401 left a dead screen** with no nav and no URL bar. | `api.ts` now returns the guest to `/join` (skipping the auth routes themselves). |
+| **Rate limiter could panic while holding its mutex** (`timestamps[0]` with `max == 0`), poisoning it process-wide. | Uses `first()` with a fail-open guard. |
+| **Hashtag deadlock** — `edit_upload` and `add_comment` upserted tags in client/text order. | Both now sort + dedup on the normalised key, matching the upload path. |
+| **Unbounded Docker logs + debug-level app logging.** | `logging:` caps every service at 30 MB; `RUST_LOG` documented in `.env.example`. |
+
+### Fixed in the readiness pass — behaviour you should know about
+
+These change what you will observe on the night, so they are listed separately from the table above.
+
+| Was | Now |
+|---|---|
+| **Any ffmpeg-level failure DESTROYED the video.** A poster-frame error — ffmpeg hanging on a truncated `.mov`, an ENOSPC on `thumbnails/`, a DB blip — propagated into the give-up path, which soft-deleted the upload. Reproduced live: on a host with no ffmpeg the clip was gone ~6 s after its `201 Created`. | No failure in the video branch can fail the upload. The clip stays in the feed and plays from its original; only the poster is missing. |
+| **A lost response duplicated the photo.** Every retry minted a fresh upload id, so a phone that lost the reply and re-sent — manually, or automatically on reconnect — stored the same photo two or three times and paid quota for each. | The client sends a `client_upload_id`; migration 022 makes it unique. A retry returns `200` with the original row. Verified live: three sends → one row, quota charged once. |
+| **`/health` returned a constant `"ok"`.** The container reported healthy while every request 500'd. | Runs `SELECT 1` with a 2 s timeout: `200 ok` / `503`. Verified live: 200 → stop Postgres → 503 → start Postgres → 200, **with no app restart** (the pool revalidates on acquire). Note that Compose does not restart on an unhealthy probe — this is a diagnostic, deliberately not wired to automatic recovery, because a restart would truncate in-flight uploads to "fix" an outage that clears on its own. |
+| **Abandoned `.tmp` uploads were never reclaimed** (see the old issue #2 below — it is now fixed, not deferred). | Swept at boot and hourly, keyed on modification time so a live upload can never age into it. |
+| **A full disk made itself worse.** ENOSPC was retried three times, then refunded the quota, soft-deleted the row and *kept* the bytes — freeing nothing and inviting an immediate re-upload into the same full disk. | ENOSPC is classified separately: no retry, no refund, no delete. The row stays live and the photo is served from its original until there is room to compress it. |
+| **The keepsake download failed invisibly.** The rate limit was enforced inside the iframe navigation, so an over-limit guest tapped and *nothing happened*, forever. | Charged when the ticket is minted — a normal `fetch` — so it surfaces as a German message naming the daily window. Raise `export_rate_per_day` per §4 anyway. |
+| **`/host` and `/admin` subscribed to SSE but never opened the connection**, so the keepsake progress bar froze after a release. | Both connect on mount and disconnect on destroy, as `/export` already did. |
+| **`?limit=-5` on the feed returned a 500.** | Clamped at both ends. |
+| **All recurring hygiene lived in one unsupervised task** — one panic silently stopped session pruning, media reclamation and the temp sweep for the rest of the event. | Supervised and re-spawned, with an error log. |
+| **No pool acquire or statement timeout.** A DB blip parked every request for 30 s. | 5 s acquire, `statement_timeout=15s`, `lock_timeout=5s`. |
+
+### Still open — accepted for this event
+
+| # | Issue | Impact |
+|---|---|---|
+| 1 | **Guest delete/caption-edit after release invalidates both keepsake archives** (`upload.rs`), forcing a rebuild with a 20 s debounce. **No-op before release**, so it cannot bite during the event. | Post-event only. Left alone because blocking guest deletes has real privacy downsides — that is a product call, not a bug fix. |
+| 2 | **Video poster frames do not regenerate after a restart** mid-compression (the backfill filters `mime_type LIKE 'image/%'`). | Cosmetic — the video still plays; only its poster is missing. |
+| 3 | **SSE keep-alives are sent as SSE comments** (`:ping`), which the browser's EventSource parser discards without dispatching. A client therefore cannot implement a pure silence timer to detect a half-open socket. | Worked around client-side: the feed runs a jittered 60–120 s `/feed/delta` backstop and reconnects when a poll returns content the stream never delivered. A cleaner fix is to emit keep-alives as a *named* event; that is a coordinated backend+frontend change, not worth making during a freeze. |
+| 4 | **The lightbox stops at the end of the loaded page** — stepping past the last loaded photo does not fetch the next one. | The guest scrolls the feed (which does page) and re-opens. |
+
+---
+
+## 13. Event-day emergency card
+
+Assume you have a phone and two minutes.
+
+```bash
+cd ~/eventsnap
+
+# FIRST LINE, ALWAYS. `.env` is read by docker compose, NOT by your shell — without this,
+# every `$DOMAIN` below expands to nothing and `curl https:///health` reads like an outage
+# when the site is fine.
+set -a; . ./.env; set +a
+
+# Is it alive? (200 = app AND database are answering; 503 = the app is up, the DB is not)
+curl -fsS https://$DOMAIN/health
+
+# What is broken?
+docker compose ps
+docker compose logs --tail=100 app
+
+# Nuclear option that is SAFE (keeps all data):
+docker compose restart app
+
+# Roll back to the identically-built sibling image — see §9 for what this can and cannot fix.
+# Do NOT substitute an older release tag here; it will crash-loop on the migration set.
+sed -i 's/^EVENTSNAP_VERSION=.*/EVENTSNAP_VERSION=v0.13.0-a/' .env && docker compose up -d app frontend
+
+# Disk check
+df -h /var/lib/docker
+```
+
+**NEVER** run `docker compose down -v`. It deletes the database, all media, all exports and the TLS
+certificate. There is no undo.
+
+Most limits are changeable from the **admin dashboard without a restart** — reach for that before
+touching the shell.

FOLLOWUPS.md

@@ -46,6 +46,90 @@ is the smallest patch.
 - [frontend/src/lib/components/Toaster.svelte](frontend/src/lib/components/Toaster.svelte) — add passthrough marker (if approach 2) or move to a portal (if approach 1)
 - [frontend/src/app.html](frontend/src/app.html) — add `<div id="modal-root">` (if approach 1)
 
+## Feed — DOM-windowing virtualization (IMPLEMENTED — residual validation owed)
+
+**Status.** Implemented in [frontend/src/lib/components/VirtualFeed.svelte](frontend/src/lib/components/VirtualFeed.svelte)
+using `@tanstack/svelte-virtual`'s `createWindowVirtualizer`. Both the **list**
+view (dynamic `measureElement` heights, keyed by upload id with `anchorTo:'start'`
+so an SSE prepend doesn't yank a scrolled-down reader) and the **grid** view
+(three measured square tiles per row) now keep only the on-screen window (+overscan)
+in the DOM instead of one node per upload. The window virtualizer scrolls the
+document, so the sticky header, pull-to-refresh, the infinite-scroll sentinel and
+the bottom nav are untouched. The earlier `content-visibility` band-aid was removed
+from `FeedListCard` (it interferes with real-height measurement), and the old
+`FeedGrid.svelte` was deleted (its sole consumer migrated to `VirtualFeed`).
+
+**Verified.** `svelte-check` 0 errors, production build clean. The integration
+follows the library's documented window-virtualizer contract (confirmed against
+`virtual-core` source: item `start` includes `scrollMargin`, `getTotalSize()`
+excludes it; the SSR path is guarded by `getScrollElement()` returning null).
+
+**Residual validation owed (needs the running app — could not be done headless).**
+- Manual scroll testing on a ~1000-item event: confirm no jank, correct scrollbar
+  size, and that an SSE `new-upload` / `feed-delta` prepend while scrolled down does
+  not jump the viewport (the `anchorTo:'start'` + id-key path).
+- `scrollMargin` re-measure when grid filter chips change the header height (handled
+  reactively via the `uploads`-length-driven effect, but unverified visually).
+- A new e2e spec that scrolls far down, likes an item via SSE, and asserts scroll
+  position is retained — the existing suite only asserts a single card is visible,
+  so it cannot catch a scroll regression.
+
+**Files.**
+- [frontend/src/lib/components/VirtualFeed.svelte](frontend/src/lib/components/VirtualFeed.svelte) — new windowing component (list + grid)
+- [frontend/src/routes/feed/+page.svelte](frontend/src/routes/feed/+page.svelte) — renders `VirtualFeed` for both views
+- [frontend/src/lib/components/FeedListCard.svelte](frontend/src/lib/components/FeedListCard.svelte) — `content-visibility` removed
+
+**Known limitations (surfaced in the post-commit review, left as-is — low impact).**
+- **Grid prepend reflows tiles.** Grid rows are index-keyed and pack 3 tiles each, so
+  an SSE `new-upload` shifts every tile by one position; `anchorTo:'start'` can only
+  anchor a scrolled grid reader when the prepend crosses a 3-item boundary (it adds a
+  *row*). List view is unaffected (one id-keyed row per upload). A fix would key rows
+  by the first tile's id and accept partial-row churn; not worth it for the rarer
+  "new upload while browsing the grid" case.
+- **Filtered grid can auto-load the whole feed.** When a grid filter matches few items
+  the `VirtualFeed` is short, so the infinite-scroll sentinel sits in-viewport and
+  `loadMore()` fires until `nextCursor` is null — pulling all pages to widen the
+  client-side search. This is pre-existing (the old `FeedGrid` had the same shape, and
+  the empty-filter copy even says "scrolle weiter"), not a virtualization regression.
+  If undesired, gate auto-load to list view or to actual user scroll.
+
+## Feed — comment deletion leaves a stale live count
+
+**Problem.** `add_comment` now broadcasts a fresh `comment_count` so feed clients patch
+the card in place, but `delete_comment` and `host_delete_comment`
+([backend/src/handlers/social.rs](backend/src/handlers/social.rs),
+[host.rs](backend/src/handlers/host.rs)) soft-delete without broadcasting any
+count/event. So a deletion leaves the count too high on every client until a full
+refetch (pull-to-refresh or an unrelated `upload-processed` merge). `toggle_like`
+already broadcasts on both add and remove, so likes are fine — the gap is
+comments-on-delete. Pre-existing, but the in-place-patch scheme makes it observable.
+
+**Fix.** Emit a `new-comment` (or a `comment-deleted`) event carrying the refreshed
+`comment_count` from both delete paths, the same best-effort way `add_comment` does;
+the frontend `patchCount(..., 'comment_count')` handler already consumes it.
+
+**Note — count ordering.** The broadcast count is read just after the (auto-committed)
+mutation, not inside it, so under concurrent likes/comments on one upload the SSE
+messages are last-write-wins. The frontend *replaces* (not increments) the count, so
+steady state is correct and self-healing; only document this if strict per-event
+ordering is ever required (then compute the count in-tx with a monotonic sequence).
+
+## Feed — per-image exact CLS reservation
+
+**Problem.** `FeedListCard` now reserves a default `aspect-[4/5]` box for photos so
+the card doesn't collapse to height 0 and reflow as images stream in (matching
+`Skeleton`). But no image dimensions are stored anywhere (not on `FeedUpload`, the
+`upload` table, or any migration), so the box is a uniform guess that crops to fit —
+the original is one tap away in the lightbox.
+
+**Acceptance criterion.** Extract image width/height during the compression worker,
+store them on `upload`, expose them on `FeedUpload`, and have the card reserve the
+*true* aspect ratio (no crop, zero shift).
+
+**Files to touch.**
+- backend: `services/compression.rs`, `models/upload.rs`, `handlers/feed.rs`, a migration
+- [frontend/src/lib/types.ts](frontend/src/lib/types.ts), [FeedListCard.svelte](frontend/src/lib/components/FeedListCard.svelte)
+
 ## Smaller nits, optional
 
 - **Auto-submit on retried 4th digit.** [recover/+page.svelte](frontend/src/routes/recover/+page.svelte), [join/+page.svelte](frontend/src/routes/join/+page.svelte) — after a wrong PIN, deleting one digit and retyping triggers an immediate submit. Backend's 3-attempts/15-min lockout makes this safe; could feel hair-trigger after a typo. Consider gating the second auto-submit per input session behind an explicit button press.

PROJECT.md

@@ -709,7 +709,7 @@ CREATE TABLE config (
 INSERT INTO config (key, value) VALUES
     ('max_image_size_mb',       '20'),
     ('max_video_size_mb',       '500'),
-    ('upload_rate_per_hour',    '10'),
+    ('upload_rate_per_hour',    '100'),  -- raised from 10 in migration 015 (guests upload bursts of 10-20)
     ('feed_rate_per_min',       '60'),
     ('export_rate_per_day',     '3'),
     ('quota_tolerance',         '0.75'),
@@ -1133,16 +1133,19 @@ eventsnap/
 
 ### Backup Strategy
 
-```bash
-# Daily (e.g. as a separate Compose service or cron on the VPS)
-pg_dump $DATABASE_URL | gzip > /media/backups/db_$(date +%Y-%m-%d).sql.gz
+Three artefacts in three places: the database, the `media_data` volume
+(originals + derivatives), and the **separate** `exports_data` volume. See
+[README.md](README.md#backup) for the exact commands.
 
-# Weekly: rsync /media volume to Hetzner Storage Box
-rsync -az /opt/eventsnap/media/ \
-  user@u123456.your-storagebox.de:backup/eventsnap/
-```
+Everything runs through `docker compose` / `docker run`, because `DATABASE_URL`
+and the `/media` and `/exports` paths only exist inside the compose network —
+they are not host paths, and `DATABASE_URL` is never exported into an operator's
+shell.
 
-The `/media` volume contains originals, previews, thumbnails, generated exports, and DB backups — a single volume to back up.
+Export archives are deliberately outside `MEDIA_PATH` (`EXPORT_PATH=/exports`): a
+keepsake contains every photo in the event, and keeping it off the media tree is
+what stops it being reachable except through the ticket-gated handler. A backup
+of the media volume alone silently loses every generated keepsake.
 
 ---
 

README.md

@@ -34,7 +34,6 @@ A guest scans the QR code on their way in, types their name, and is immediately
 ### Planned (v1.x)
 
 - Individual file download button
-- Low-disk alert (< 10 GB free)
 - Event banner / cover image
 - Chunked resumable upload for large videos
 - Host-curated story highlights
@@ -77,6 +76,7 @@ eventsnap/
 │   ├── svelte.config.js
 │   └── Dockerfile
 ├── docker-compose.yml
+├── docker-compose.dev.yml   # opt-in dev overlay (publishes Postgres on the host)
 ├── Caddyfile
 └── .env.example
 ```
@@ -93,30 +93,139 @@ eventsnap/
 ### Deploy on a fresh VPS
 
 ```bash
-# 1. Clone the repository
-git clone https://git.mc02.dev/fabi/EventSnap.git
-cd EventSnap
+# 1. Clone the repository (into a lowercase dir, matching the paths used below)
+git clone https://git.mc02.dev/fabi/EventSnap.git eventsnap
+cd eventsnap
 
-# 2. Configure environment
+# 2. Configure environment — set EVERY secret NOW, before step 3.
 cp .env.example .env
-nano .env   # set DOMAIN, JWT_SECRET, ADMIN_PASSWORD_HASH, EVENT_NAME, etc.
+nano .env   # DOMAIN, EVENT_NAME, EVENT_SLUG,
+            # JWT_SECRET, ADMIN_PASSWORD_HASH,
+            # POSTGRES_PASSWORD *and* the same password inside DATABASE_URL
+            # (see "Generate required secrets" below)
 
 # 3. Start the stack
 docker compose up -d
 ```
 
+> **Set every secret before step 3 — `POSTGRES_PASSWORD` especially.** Postgres reads it **only
+> when it initialises its data directory**, which happens on the very first `docker compose up -d`.
+> Changing it in `.env` afterwards does not change the stored password: the app then authenticates
+> with the new one against a volume holding the old one, and you get a permanent restart loop with
+> `password authentication failed for user "eventsnap"`. The only fixes are restoring the old
+> password or `docker compose down -v`, which **deletes the database, the media and the exports**.
+> Getting it right once, up front, costs nothing; getting it wrong costs the volume.
+
 Caddy automatically obtains a Let's Encrypt certificate on first start. The app is live at `https://DOMAIN` within ~30 seconds.
 
+> **If the site never comes up:** with `APP_ENV=production` the backend **refuses to boot** while
+> `JWT_SECRET`, `ADMIN_PASSWORD_HASH` or the password inside `DATABASE_URL` still hold the
+> `.env.example` placeholders (this is deliberate — a publicly-known signing key or database
+> password is worse than downtime). Caddy then waits on the unhealthy `app` container and never
+> serves. Check `docker compose logs app` — a "Refusing to start … placeholder …" line lists
+> **every** unset secret at once, so one edit fixes them all.
+>
+> **If it comes up but keeps restarting with `password authentication failed for user
+> "eventsnap"`:** `POSTGRES_PASSWORD` was changed after the database volume was created. Postgres
+> applies that variable only at initialisation, so `.env` and the stored password have drifted
+> apart permanently. `docker compose logs app` spells this out. Before the event, with nothing
+> worth keeping:
+>
+> ```bash
+> docker compose down -v && docker compose up -d   # -v DELETES db + media + exports. No undo.
+> ```
+>
+> **Once the event has real data, never do that.** Put the original password back into
+> `DATABASE_URL`, or change the stored one instead:
+>
+> ```bash
+> docker compose exec db psql -U "$POSTGRES_USER" -c \
+>   "ALTER ROLE eventsnap WITH PASSWORD 'the-password-now-in-your-.env';"
+> ```
+
+> **Production note:** `docker compose up -d` does **not** expose the database — Postgres is reachable only on the internal Docker network. For local development where you need host access to Postgres, opt into the dev overlay explicitly:
+> ```bash
+> docker compose -f docker-compose.yml -f docker-compose.dev.yml up
+> ```
+
+### Updating an existing deployment
+
+> **`docker compose up -d` alone will NOT deploy your changes.** `app` and `frontend` are
+> `build:` services with no published image tag, and Compose has no source-change detection:
+> if an image with that name already exists it is reused. After a `git pull` the command
+> reports `Container … Running`, changes nothing, and **exits 0** — so a deploy that shipped
+> nothing looks exactly like a successful one. `--build` is what makes it real.
+
+```bash
+cd /path/to/eventsnap
+
+# 1. Back up first — migrations run automatically on boot and are not reversible in place.
+#    (See "Backup" below; the database dump is the one that matters here.)
+
+# 2. Fetch the new code.
+git pull
+
+# 3. Rebuild and restart the application services. --build is NOT optional.
+docker compose up -d --build
+
+# 4. Apply any Caddyfile change. Step 3 does NOT do this — see the warning below.
+docker compose up -d --force-recreate caddy
+
+# 5. Confirm the app came back up. Anything other than "ok" means check the logs.
+curl -fsS https://DOMAIN/health && echo
+
+# 6. Confirm a NEW image was actually built. Note the IMAGE ID before you start and
+#    compare — it must have changed. (Ignore the CREATED column; it reports the base
+#    layer's age, not this build's.) An unchanged ID means step 3 ran without --build
+#    and you are still serving the old code.
+docker compose images app frontend
+```
+
+Migrations are applied by the backend on startup, so step 3 covers them. If `app` stays
+unhealthy afterwards, `docker compose logs app` will name the failing migration — and note
+that a migration applied by a *newer* build is not removed by checking out an older commit,
+so rolling back code without restoring the database snapshot from step 1 leaves the schema
+ahead of the binary and the app refusing to boot.
+
+> **Why step 4 exists.** `--build` only rebuilds services that have a `build:` section, and
+> `caddy` is a pinned upstream image. Compose decides whether to recreate a container from its
+> *config hash*, which covers the mount **specification** (`./Caddyfile:/etc/caddy/Caddyfile:ro`)
+> but **not the file's contents** — so a `git pull` that changes `./Caddyfile` produces no
+> delta, Compose reports `Running`, and Caddy keeps serving its old config indefinitely. Exit
+> code 0 throughout.
+>
+> That is not hypothetical: the fix that made the keepsake download work on iOS
+> (`137c4ee`) touched the Caddyfile and four e2e files and nothing else, so **all** of its
+> production effect lives in that one file. Without step 4 you deploy it, watch both image IDs
+> change, and iOS downloads stay broken.
+>
+> `--force-recreate` rather than `restart` or `caddy reload`: the bind mount is resolved to an
+> **inode** when the container is created, and `git pull` replaces the file instead of editing
+> it in place, so the container can still be bound to the old, now-unlinked inode. A restart
+> then re-reads the stale content. Recreating the container re-resolves the path.
+
+`db` is never touched, and recreating `caddy` does not disturb the `caddy_data` volume, so the
+TLS certificate and all data volumes survive.
+
 ### Generate required secrets
 
 ```bash
 # JWT secret (64 random bytes)
 openssl rand -hex 64
 
-# Admin password hash (bcrypt, cost 12)
-htpasswd -bnBC 12 "" yourpassword | tr -d ':\n'
+# Database password (goes in BOTH DATABASE_URL and POSTGRES_PASSWORD)
+openssl rand -hex 24
+
+# Admin password hash (bcrypt). Uses an image the stack already pulls, so it needs
+# nothing installed on the host — `htpasswd` lives in apache2-utils, which a stock
+# VPS does not have. Emits cost 14 rather than 12; that is fine (admin login is
+# rate-limited and hashed off the async runtime), and any $2a/$2b/$2y hash verifies.
+docker run --rm caddy:2-alpine caddy hash-password --plaintext 'yourpassword'
 ```
 
+Wrap the resulting hash in **single quotes** in `.env` — see the note there; a bcrypt
+hash is full of `$`, and both Compose and dotenvy would otherwise eat those segments.
+
 ### Environment Variables
 
 See [.env.example](.env.example) for the full list with descriptions and defaults. Key variables:
@@ -154,26 +263,215 @@ See [.env.example](.env.example) for the full list with descriptions and default
 └────────┘
 ```
 
-- `/api/*` and `/media/*` → Rust backend
+- `/api/*` → Rust backend
 - Everything else → SvelteKit frontend (`adapter-node`)
-- Named volumes: `postgres_data`, `media_data`, `caddy_data`
+- Named volumes: `postgres_data`, `media_data`, `exports_data`, `caddy_data`
+
+Media is **not** served as static files. Every image goes through a
+visibility-checked alias (`/api/v1/upload/{id}/{preview,display,thumbnail,original}`)
+so a host takedown or a ban actually revokes access to the bytes.
+
+---
+
+## Sizing the disk
+
+`postgres_data`, `media_data` and `exports_data` are all Docker named volumes under
+`/var/lib/docker/volumes`, so **they share one filesystem**. Filling it does not
+degrade one subsystem — Postgres stops being able to write and the whole event goes
+down.
+
+**`Gallery.zip` and `Memories.zip` are each roughly a second copy of every original.**
+Both write their media `Compression::Stored`, and `Memories.zip` streams the untouched
+original for every video and for every image at or under 5 MB. So a release wants room
+for **two more copies of the gallery** on top of the gallery itself — which is what
+`required_free_bytes` encodes as `media × 1.1 × 2`.
+
+The per-user quota does **not** bound this. It is a fairness mechanism that divides
+free space between guests, and since it carries a floor (`MIN_QUOTA_LIMIT_BYTES`, so a
+guest's allowance stops shrinking as the party fills up) the aggregate ceiling it used
+to imply is gone. What bounds the disk is the **global gate in the upload handler**,
+which refuses any upload that would leave too little room to build the keepsake:
+
+```
+free_after_upload  <  media_after × 1.1 × 2  +  DISK_RESERVE_BYTES   →   refused
+```
+
+Solving that for the gallery size gives the real ceiling. On the **40 GB box this runs
+on**, with ~5 GB for the OS, Docker images (the runbook pre-pulls the rollback tag too)
+and Postgres:
+
+| Volume | Usable after baseline | Media ceiling | Free at release |
+|---|---|---|---|
+| 40 GB | ~35 GB | **~8 GB** | ~27 GB → both archives fit |
+| 80 GB | ~70 GB | ~19 GB | ~51 GB → both archives fit |
+
+**Uploads therefore stop at roughly 8 GB of media on a 40 GB box, not when the disk is
+full.** That is deliberate. 1000 photos at ~3.5 MB is ~3.5 GB and fits comfortably;
+video is what consumes the budget, so lower `max_video_size_mb` (seeded at 500) if you
+expect a lot of it. Refusing the 1001st upload is a far better outcome than accepting it
+and discovering at 01:00 that the archive can never be built.
+
+Two ways to buy headroom:
+
+- **Provision ~3× your expected media** on one volume (media + two archives), or
+- **give `exports_data` its own volume** so a full export cannot reach Postgres, and
+  size that one at ~2× expected media.
+
+None of this is silent. The upload gate refuses with a German message naming the cause,
+the export preflight refuses up front with both numbers rather than hitting ENOSPC
+halfway through a multi-GB write, a rebuild only reclaims the superseded generation
+**after** the new one lands (so a failed rebuild can never leave you with no archive at
+all), and the host dashboard warns as soon as the keepsake would not fit — which is the
+only point at which anyone can still do something about it.
 
 ---
 
 ## Backup
 
-```bash
-# Database snapshot
-pg_dump $DATABASE_URL | gzip > /media/backups/db_$(date +%Y-%m-%d).sql.gz
+There are **three** things to back up, and they live in three different places.
+`DATABASE_URL` and the container paths (`/media`, `/exports`) are meaningful only
+*inside* the compose network — they are not host paths, and `DATABASE_URL` is
+never exported into an operator's shell — so every command below runs through
+`docker compose` from the repo directory.
 
-# Weekly offsite sync (Hetzner Storage Box or similar)
-rsync -az /opt/eventsnap/media/ user@storagebox.example.com:backup/eventsnap/
+```bash
+# 1. Database snapshot. Runs pg_dump inside the db container (the app image has no
+#    postgres client), reading credentials from the compose environment.
+#    --clean --if-exists makes the dump SELF-CLEANING: without it the restore below
+#    aborts on the first "already exists" against a database that has ever booted,
+#    which is every database you would actually want to restore over.
+mkdir -p ./backups
+docker compose exec -T db \
+  sh -c 'pg_dump --clean --if-exists -U "$POSTGRES_USER" "$POSTGRES_DB"' \
+  | gzip > ./backups/db_$(date +%Y-%m-%d).sql.gz
+
+# 2. Uploaded media (originals + derivatives) out of the named volume.
+#    NOTE the mountpoint is /src, not /media: if the volume is ever empty, Docker
+#    pre-populates a fresh mount from the image's own directory, and alpine ships a
+#    /media containing cdrom/floppy/usb. Mounting somewhere the image has nothing
+#    avoids silently tarring (and polluting the volume with) those.
+docker run --rm \
+  -v eventsnap_media_data:/src:ro -v "$PWD/backups":/backup \
+  alpine tar czf /backup/media_$(date +%Y-%m-%d).tar.gz -C /src .
+
+# 3. Export archives — a SEPARATE volume (see the security note below).
+docker run --rm \
+  -v eventsnap_exports_data:/src:ro -v "$PWD/backups":/backup \
+  alpine tar czf /backup/exports_$(date +%Y-%m-%d).tar.gz -C /src .
+
+# Offsite sync of the three artefacts above.
+rsync -az ./backups/ user@storagebox.example.com:backup/eventsnap/
 ```
 
-The `/media` volume holds originals, previews, thumbnails, exports, and DB backups — a single path to back up.
+Volume names are prefixed with the compose project name — `eventsnap_` if you run
+from a directory called `eventsnap`. Confirm yours with `docker volume ls`.
+
+> **Exports are deliberately NOT under `/media`.** They live on their own
+> `exports_data` volume (`EXPORT_PATH=/exports`) because a keepsake archive
+> contains every photo in the event; keeping it outside the media tree is what
+> stops it being reachable except through the ticket-gated download handler.
+> Backing up only the media volume therefore loses every generated keepsake.
+
+### When to run it
+
+**A nightly cron is the wrong shape for this app.** Every irreplaceable byte is
+created inside one eight-hour window, and nobody can retake a wedding. Run the three
+commands above:
+
+1. **The night of the event**, once uploads have stopped. This is the backup that
+   matters; everything else is a formality.
+2. **After the host releases the gallery**, so the generated keepsake is captured too.
+3. Weekly thereafter, until the event is archived and torn down.
+
+Take the DB dump and the media tarball **back to back**, without uploads in flight
+between them. Upload rows reference files by path — a database from 22:00 and a media
+volume from 23:00 gives you rows pointing at files the dump doesn't know about, and
+rows whose files aren't in the tarball. Locking uploads from the host dashboard first
+(**Uploads sperren**) makes the pair genuinely consistent.
 
 ---
 
+## Restore
+
+An untested backup is not a backup. Run this once against a scratch host **before**
+the event — it is roughly ten minutes, and it is the only way to find out that your
+tarball is empty or your dump is truncated while that is still a small problem.
+
+```bash
+# 0. Stop the app FIRST. Migrations run on boot and a live pool will fight the
+#    restore — a booting app against a half-restored schema can leave the migration
+#    table and the schema disagreeing, which is its own recovery problem.
+#    Leave `db` running: the dump is restored through it.
+docker compose stop app caddy
+
+# 1. Database. The dump carries its own DROPs (step 1 of Backup), so this replaces
+#    rather than collides. A dump taken WITHOUT --clean --if-exists will abort here
+#    on the first "already exists" — restore that one into a fresh empty database
+#    instead.
+gunzip -c ./backups/db_2026-07-29.sql.gz \
+  | docker compose exec -T db \
+      sh -c 'psql -U "$POSTGRES_USER" -d "$POSTGRES_DB" --set ON_ERROR_STOP=1'
+
+# 2. Media. NOTE the `--numeric-owner` and the chown: the app runs as a
+#    NON-ROOT user (uid 100, gid 101 — `addgroup -S app && adduser -S app`), and a
+#    restore that lands root-owned files makes every upload fail with EACCES deep in
+#    the write path, surfacing to the guest as a generic 500 with nothing in the UI
+#    to suggest permissions. The explicit chown is what guarantees it — BusyBox tar
+#    (which is what `alpine` ships) has no --same-owner, and restores ownership only
+#    because it runs as root here.
+docker run --rm \
+  -v eventsnap_media_data:/dst -v "$PWD/backups":/backup:ro \
+  alpine sh -c 'tar xzf /backup/media_2026-07-29.tar.gz -C /dst \
+                    --numeric-owner && chown -R 100:101 /dst'
+
+# 3. Exports. Same volume-name caveat, same ownership rules.
+docker run --rm \
+  -v eventsnap_exports_data:/dst -v "$PWD/backups":/backup:ro \
+  alpine sh -c 'tar xzf /backup/exports_2026-07-29.tar.gz -C /dst \
+                    --numeric-owner && chown -R 100:101 /dst'
+
+# 4. Back up. Migrations run, then export recovery re-arms any keepsake whose file
+#    didn't come back with the volume.
+docker compose up -d app caddy
+docker compose logs -f app        # watch for "migrations applied"
+
+# 5. Verify — all three, not just the first.
+curl -fsS https://DOMAIN/health && echo            # → ok
+#   … then sign in as host and confirm the feed renders images (proves the media
+#   volume restored AND is readable by uid 100), and that the keepsake downloads.
+```
+
+If the media volume restored but images 404 while the feed lists them, the paths are
+there and the bytes aren't — check `docker compose exec app ls -ln /media/originals`
+and confirm both the files and the `100:101` ownership.
+
+The restore is deliberately **not** automated. It is rare, destructive, and the one
+operation where a script that half-works is worse than a checklist someone reads.
+
+---
+
+## Running the backend test suite
+
+```bash
+cd backend
+
+# The DB-backed integration tests (backend/tests/) need a live Postgres. `#[sqlx::test]` creates a
+# throwaway database per test and runs backend/migrations/ into it — it does NOT touch this one's data.
+docker run -d --name eventsnap-test-pg -p 55433:5432 \
+  -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=eventsnap postgres:16-alpine
+
+export DATABASE_URL=postgres://postgres:postgres@localhost:55433/eventsnap
+cargo test        # 44 unit + 12 DB-backed
+cargo clippy --all-targets -- -D warnings
+```
+
+**`cargo test` requires `DATABASE_URL`** — without it the integration tests panic rather than skip.
+That is deliberate. The riskiest code in this repo is SQL (the export epoch state machine, the
+atomic quota increment, the `FOR SHARE` upload lock), and for a long time *not one line of it* was
+executed by `cargo test` — every backend test was a pure-function test, so the tests clustered
+tightly around the code that could not break and stopped exactly where it started to. Tests that
+silently skip when the database is absent recreate that hole; they were meant to be a gate.
+
 ## Running the E2E test suite
 
 Playwright-based end-to-end tests live in [`e2e/`](e2e/). They spin up an isolated docker-compose stack (Postgres on `:55432`, Caddy on `:3101`) and exercise the SvelteKit frontend against the real Rust backend with rate limits disabled.
@@ -190,7 +488,14 @@ npm run stack:down            # tear it down
 
 See [`e2e/README.md`](e2e/README.md) for the full UA matrix, Samsung Internet escalation tiers, and the Phase 2/3 roadmap.
 
-CI runs this on every PR — see [`.github/workflows/e2e.yml`](.github/workflows/e2e.yml).
+CI runs this on every PR — see [`.github/workflows/e2e.yml`](.github/workflows/e2e.yml) (desktop **and**
+mobile projects), plus [`checks.yml`](.github/workflows/checks.yml) for `cargo test`/clippy, the frontend
+unit tests, svelte-check and the e2e typecheck, and [`audit.yml`](.github/workflows/audit.yml) for
+dependency advisories.
+
+**Playwright runs with `retries: 0`, including in CI.** This repo's real bugs are races, and from the
+outside a race is indistinguishable from a flake — so a retry silently resolves that ambiguity in
+favour of "flake" every time. A flake here is a bug report; treat it as one.
 
 ---
 
@@ -217,7 +522,7 @@ Open:
 - [ ] SSE delta-fetch on foreground reconnect (scaffolded in [sse.ts](frontend/src/lib/sse.ts), not wired)
 - [ ] Live diashow / slideshow mode — see [docs/CONCEPT_DIASHOW.md](docs/CONCEPT_DIASHOW.md)
 - [ ] Individual file download button per post
-- [ ] Low-disk alert (< 10 GB free)
+- [x] Low-disk alert — host dashboard warns below 10 GB free, or whenever the keepsake would not fit
 - [ ] Event banner / cover image
 - [ ] Chunked resumable upload for files > 100 MB
 - [ ] Shared Tailwind config between main app and export-viewer

backend/.dockerignore

@@ -0,0 +1,12 @@
+# Build context exclusions.
+#
+# `target/` does not exist on a clean checkout, which is why builds have worked without this
+# file — but the moment anyone runs `cargo build` locally it becomes multi-GB, and every
+# `docker build` would ship all of it to the daemon for nothing (the Dockerfile only COPYs
+# Cargo.toml, Cargo.lock, src, static and migrations). On an EMULATED amd64 builder that
+# transfer is the slowest part of the build.
+target/
+
+# Never let a real .env reach an image layer.
+.env
+.env.*

backend/Cargo.lock

@@ -65,56 +65,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "anstream"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "824a212faf96e9acacdbd09febd34438f8f711fb84e09a8916013cd7815ca28d"
-dependencies = [
- "anstyle",
- "anstyle-parse",
- "anstyle-query",
- "anstyle-wincon",
- "colorchoice",
- "is_terminal_polyfill",
- "utf8parse",
-]
-
-[[package]]
-name = "anstyle"
-version = "1.0.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "940b3a0ca603d1eade50a4846a2afffd5ef57a9feac2c0e2ec2e14f9ead76000"
-
-[[package]]
-name = "anstyle-parse"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "52ce7f38b242319f7cabaa6813055467063ecdc9d355bbb4ce0c68908cd8130e"
-dependencies = [
- "utf8parse",
-]
-
-[[package]]
-name = "anstyle-query"
-version = "1.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
-dependencies = [
- "windows-sys 0.61.2",
-]
-
-[[package]]
-name = "anstyle-wincon"
-version = "3.0.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
-dependencies = [
- "anstyle",
- "once_cell_polyfill",
- "windows-sys 0.61.2",
-]
-
 [[package]]
 name = "anyhow"
 version = "1.0.102"
@@ -554,46 +504,12 @@ dependencies = [
  "inout",
 ]
 
-[[package]]
-name = "clap"
-version = "4.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b193af5b67834b676abd72466a96c1024e6a6ad978a1f484bd90b85c94041351"
-dependencies = [
- "clap_builder",
-]
-
-[[package]]
-name = "clap_builder"
-version = "4.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "714a53001bf66416adb0e2ef5ac857140e7dc3a0c48fb28b2f10762fc4b5069f"
-dependencies = [
- "anstream",
- "anstyle",
- "clap_lex",
- "strsim",
- "terminal_size",
-]
-
-[[package]]
-name = "clap_lex"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c8d4a3bb8b1e0c1050499d1815f5ab16d04f0959b233085fb31653fbfc9d98f9"
-
 [[package]]
 name = "color_quant"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3d7b894f5411737b7867f4827955924d7c254fc9f4d91a6aad6b097804b1018b"
 
-[[package]]
-name = "colorchoice"
-version = "1.0.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d07550c9036bf2ae0c684c4297d503f838287c83c53686d05370d0e139ae570"
-
 [[package]]
 name = "compression-codecs"
 version = "0.4.37"
@@ -677,15 +593,6 @@ dependencies = [
  "cfg-if",
 ]
 
-[[package]]
-name = "crossbeam-channel"
-version = "0.5.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "82b8f8f868b36967f9606790d1903570de9ceaf870a7bf9fbbd3016d636a2cb2"
-dependencies = [
- "crossbeam-utils",
-]
-
 [[package]]
 name = "crossbeam-deque"
 version = "0.8.6"
@@ -816,27 +723,6 @@ dependencies = [
  "cfg-if",
 ]
 
-[[package]]
-name = "env_filter"
-version = "1.0.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32e90c2accc4b07a8456ea0debdc2e7587bdd890680d71173a15d4ae604f6eef"
-dependencies = [
- "log",
-]
-
-[[package]]
-name = "env_logger"
-version = "0.11.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0621c04f2196ac3f488dd583365b9c09be011a4ab8b9f37248ffcc8f6198b56a"
-dependencies = [
- "anstream",
- "anstyle",
- "env_filter",
- "log",
-]
-
 [[package]]
 name = "equator"
 version = "0.4.2"
@@ -1229,12 +1115,6 @@ dependencies = [
  "weezl",
 ]
 
-[[package]]
-name = "glob"
-version = "0.3.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"
-
 [[package]]
 name = "governor"
 version = "0.6.3"
@@ -1622,7 +1502,6 @@ checksum = "7714e70437a7dc3ac8eb7e6f8df75fd8eb422675fc7678aff7364301092b1017"
 dependencies = [
  "equivalent",
  "hashbrown 0.16.1",
- "rayon",
  "serde",
  "serde_core",
 ]
@@ -1656,12 +1535,6 @@ dependencies = [
  "syn",
 ]
 
-[[package]]
-name = "is_terminal_polyfill"
-version = "1.70.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a6cb138bb79a146c1bd460005623e142ef0181e3d0219cb493e02f7d08a35695"
-
 [[package]]
 name = "itertools"
 version = "0.14.0"
@@ -1795,12 +1668,6 @@ dependencies = [
  "vcpkg",
 ]
 
-[[package]]
-name = "linux-raw-sys"
-version = "0.12.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a66949e030da00e8c7d4434b251670a91556f4144941d37452769c25d58a53"
-
 [[package]]
 name = "litemap"
 version = "0.8.1"
@@ -2089,12 +1956,6 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
-[[package]]
-name = "once_cell_polyfill"
-version = "1.70.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
-
 [[package]]
 name = "oxipng"
 version = "9.1.5"
@@ -2102,18 +1963,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "26c613f0f566526a647c7473f6a8556dbce22c91b13485ee4b4ec7ab648e4973"
 dependencies = [
  "bitvec",
- "clap",
- "crossbeam-channel",
- "env_logger",
  "filetime",
- "glob",
  "indexmap",
  "libdeflater",
  "log",
- "rayon",
  "rgb",
  "rustc-hash",
- "zopfli",
 ]
 
 [[package]]
@@ -2607,19 +2462,6 @@ version = "2.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94300abf3f1ae2e2b8ffb7b58043de3d399c73fa6f4b73826402a5c457614dbe"
 
-[[package]]
-name = "rustix"
-version = "1.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6fe4565b9518b83ef4f91bb47ce29620ca828bd32cb7e408f0062e9930ba190"
-dependencies = [
- "bitflags",
- "errno",
- "libc",
- "linux-raw-sys",
- "windows-sys 0.61.2",
-]
-
 [[package]]
 name = "rustversion"
 version = "1.0.22"
@@ -3060,12 +2902,6 @@ dependencies = [
  "unicode-properties",
 ]
 
-[[package]]
-name = "strsim"
-version = "0.11.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
-
 [[package]]
 name = "subtle"
 version = "2.6.1"
@@ -3120,16 +2956,6 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "55937e1799185b12863d447f42597ed69d9928686b8d88a1df17376a097d8369"
 
-[[package]]
-name = "terminal_size"
-version = "0.4.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "230a1b821ccbd75b185820a1f1ff7b14d21da1e442e22c0863ea5f08771a8874"
-dependencies = [
- "rustix",
- "windows-sys 0.61.2",
-]
-
 [[package]]
 name = "thiserror"
 version = "1.0.69"
@@ -3505,12 +3331,6 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b6c140620e7ffbb22c2dee59cafe6084a59b5ffc27a8859a5f0d494b5d52b6be"
 
-[[package]]
-name = "utf8parse"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
-
 [[package]]
 name = "uuid"
 version = "1.23.0"
@@ -4187,18 +4007,6 @@ version = "1.0.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8848ee67ecc8aedbaf3e4122217aff892639231befc6a1b58d29fff4c2cabaa"
 
-[[package]]
-name = "zopfli"
-version = "0.8.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f05cd8797d63865425ff89b5c4a48804f35ba0ce8d125800027ad6017d2b5249"
-dependencies = [
- "bumpalo",
- "crc32fast",
- "log",
- "simd-adler32",
-]
-
 [[package]]
 name = "zstd"
 version = "0.13.3"

backend/Cargo.toml

@@ -27,7 +27,17 @@ tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 dotenvy = "0.15"
 sysinfo = "0.32"
 image = "0.25"
-oxipng = "9"
+# default-features = false drops "parallel", which is what actually bounds oxipng's memory:
+# with rayon it evaluates row filters concurrently, each trial holding its own full-size
+# buffer, and there is no Options knob to cap that. Without the feature, lib.rs swaps in a
+# sequential shim (oxipng's own supported path) so peak scales with ONE trial, not N.
+# PNG optimisation gets slower; it is a background, best-effort, lossless size saving.
+#
+# "filetime" must be KEPT: without it OutFile::Path { preserve_attrs: true } silently no-ops.
+# Dropping "binary" also removes clap/glob/env_logger — a CLI's dependencies that were being
+# compiled into a server image — and "zopfli", which preset 2 does not use (it selects
+# Deflaters::Libdeflater, which is not feature-gated).
+oxipng = { version = "9", default-features = false, features = ["filetime"] }
 async_zip = { version = "0.0.17", features = ["tokio", "deflate"] }
 include_dir = "0.7"
 infer = "0.15"

backend/Dockerfile

@@ -18,18 +18,20 @@ RUN touch src/main.rs && cargo build --release
 # --- Runtime stage ---
 FROM alpine:3.21
 
-# Run as an unprivileged user (defense-in-depth). The media volume mounts at
-# /media; creating it here as `app` means a fresh named volume inherits app
-# ownership and is writable without running as root. (An existing root-owned
-# volume from a prior deploy needs a one-time `chown -R app:app` — see deploy notes.)
-RUN apk add --no-cache ca-certificates ffmpeg \
-    && addgroup -S app && adduser -S -G app app \
-    && mkdir -p /media && chown app:app /media
+RUN apk add --no-cache ca-certificates ffmpeg
+
+# Run as a non-root user. Pre-create and chown the media + export mount paths so
+# the fresh named volumes inherit the non-root ownership (Docker seeds an empty
+# named volume from the image directory, preserving its uid/gid) and uploads +
+# export archives can be written. Exports live OUTSIDE /media on purpose so the
+# public media ServeDir can't reach them.
+RUN addgroup -S app && adduser -S app -G app
 
 WORKDIR /app
 COPY --from=builder /app/target/release/eventsnap-backend ./
-RUN chown -R app:app /app
 
+RUN mkdir -p /media /exports && chown -R app:app /app /media /exports
 USER app
+
 EXPOSE 3000
 CMD ["./eventsnap-backend"]

backend/migrations/010_feed_view_perf.up.sql

@@ -1,26 +0,0 @@
--- H6: replace v_feed's double LEFT JOIN + COUNT(DISTINCT) (which materializes a
--- likes×comments Cartesian per upload before de-duping) with correlated scalar
--- subqueries. Each count now uses its own index (idx_like_upload /
--- idx_comment_upload) and there is no GROUP BY. The output columns are
--- unchanged, so every consumer keeps working.
-CREATE OR REPLACE VIEW v_feed AS
-SELECT
-    u.id,
-    u.event_id,
-    u.user_id,
-    usr.display_name             AS uploader_name,
-    usr.is_banned,
-    usr.uploads_hidden,
-    u.preview_path,
-    u.thumbnail_path,
-    u.mime_type,
-    u.caption,
-    u.created_at,
-    (SELECT COUNT(*) FROM "like" l
-       WHERE l.upload_id = u.id)                              AS like_count,
-    (SELECT COUNT(*) FROM comment c
-       WHERE c.upload_id = u.id AND c.deleted_at IS NULL)     AS comment_count
-FROM upload u
-JOIN "user" usr ON u.user_id = usr.id
-WHERE u.deleted_at IS NULL
-  AND usr.uploads_hidden = FALSE;

backend/migrations/010_review_indexes.down.sql

@@ -0,0 +1,3 @@
+DROP INDEX IF EXISTS idx_comment_hashtag_hashtag;
+DROP INDEX IF EXISTS idx_comment_user;
+DROP INDEX IF EXISTS idx_upload_event_created_id;

backend/migrations/010_review_indexes.up.sql

@@ -0,0 +1,17 @@
+-- Composite feed index with an id tiebreaker so keyset pagination
+-- (ORDER BY created_at DESC, id DESC) stays index-covered and stable when
+-- multiple uploads share a created_at timestamp.
+CREATE INDEX idx_upload_event_created_id
+    ON upload(event_id, created_at DESC, id DESC)
+    WHERE deleted_at IS NULL;
+
+-- A user's own comments (moderation, "who commented"). The sibling
+-- idx_upload_user already exists for uploads; comment(user_id) was missing.
+CREATE INDEX idx_comment_user
+    ON comment(user_id)
+    WHERE deleted_at IS NULL;
+
+-- Hashtag filtering over comments — mirrors idx_upload_hashtag_hashtag, which
+-- only covered upload_hashtag.
+CREATE INDEX idx_comment_hashtag_hashtag
+    ON comment_hashtag(hashtag_id);

backend/migrations/011_ban_hides_and_pin_reset.down.sql

@@ -1,4 +1,6 @@
--- Restore the original join-based v_feed definition.
+DROP TABLE IF EXISTS pin_reset_request;
+
+-- Restore v_feed without the is_banned filter.
 CREATE OR REPLACE VIEW v_feed AS
 SELECT
     u.id,

backend/migrations/011_ban_hides_and_pin_reset.up.sql

@@ -0,0 +1,39 @@
+-- Ban now ALWAYS hides: exclude banned uploaders from the feed view. Previously ban and
+-- hide were decoupled (a host could ban without hiding), leaving a banned user's photos on
+-- the feed and baked into the export. `find_visible_media` and the export query get the
+-- same `is_banned = FALSE` filter in code.
+CREATE OR REPLACE VIEW v_feed AS
+SELECT
+    u.id,
+    u.event_id,
+    u.user_id,
+    usr.display_name             AS uploader_name,
+    usr.is_banned,
+    usr.uploads_hidden,
+    u.preview_path,
+    u.thumbnail_path,
+    u.mime_type,
+    u.caption,
+    u.created_at,
+    COUNT(DISTINCT l.user_id)    AS like_count,
+    COUNT(DISTINCT c.id)         AS comment_count
+FROM upload u
+JOIN "user" usr ON u.user_id = usr.id
+LEFT JOIN "like" l  ON l.upload_id = u.id
+LEFT JOIN comment c ON c.upload_id = u.id AND c.deleted_at IS NULL
+WHERE u.deleted_at IS NULL
+  AND usr.uploads_hidden = FALSE
+  AND usr.is_banned = FALSE
+GROUP BY u.id, usr.display_name, usr.is_banned, usr.uploads_hidden;
+
+-- pin_reset_request: a guest who forgot their PIN (localStorage was the only copy) can ask
+-- a host to reset it in-app, instead of being permanently orphaned. One pending request per
+-- user; cleared when the host resets the PIN or dismisses it, and cascades if the user/event
+-- is removed.
+CREATE TABLE pin_reset_request (
+    id          UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+    event_id    UUID        NOT NULL REFERENCES event(id) ON DELETE CASCADE,
+    user_id     UUID        NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (user_id)
+);

backend/migrations/012_export_release_seq.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE export_job
+    DROP COLUMN IF EXISTS release_seq;

backend/migrations/012_export_release_seq.up.sql

@@ -0,0 +1,11 @@
+-- H1: export generation guard. A reopen (which clears `export_released_at`) followed by a
+-- re-release could spawn a fresh export worker while a worker from the PRIOR release was
+-- still streaming a now-stale snapshot to `Gallery.zip`. The stale worker's finalize then
+-- re-set `export_*_ready = TRUE` on an archive that predated the reopen — a silent,
+-- permanent data loss (new uploads missing from a "ready" keepsake).
+--
+-- `release_seq` is a per-(event,type) generation counter bumped on every (re)release.
+-- A worker captures the seq it claimed and only finalizes / flips the ready flag while
+-- that seq is still current; a superseded worker discards its output instead.
+ALTER TABLE export_job
+    ADD COLUMN release_seq BIGINT NOT NULL DEFAULT 0;

backend/migrations/013_uploads_hidden_at.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "user"
+    DROP COLUMN IF EXISTS uploads_hidden_at;

backend/migrations/013_uploads_hidden_at.up.sql

@@ -0,0 +1,12 @@
+-- Ban-replay on reconnect. A ban is not a soft-delete (it sets `uploads_hidden`/`is_banned`,
+-- never `upload.deleted_at`), and live eviction rode only on the ephemeral `user-hidden` SSE
+-- broadcast — which has no reconnect-replay. So a client (especially the unattended diashow
+-- projector) that missed that broadcast kept cycling the banned user's already-loaded slides.
+--
+-- `uploads_hidden_at` stamps WHEN a user's uploads became hidden, so the reconnect delta can
+-- return the set of users hidden since the client's cursor and the client can evict them.
+ALTER TABLE "user"
+    ADD COLUMN uploads_hidden_at TIMESTAMPTZ;
+
+-- Backfill already-hidden users so a reconnect right after this migration still evicts them.
+UPDATE "user" SET uploads_hidden_at = NOW() WHERE uploads_hidden = TRUE;

backend/migrations/014_export_epoch.down.sql

@@ -0,0 +1,28 @@
+-- Restore the stored ready flags and the per-job counter.
+DROP VIEW IF EXISTS export_current;
+
+ALTER TABLE event ADD COLUMN export_zip_ready  BOOLEAN NOT NULL DEFAULT FALSE;
+ALTER TABLE event ADD COLUMN export_html_ready BOOLEAN NOT NULL DEFAULT FALSE;
+
+-- Re-derive the flags from what the epoch model considers downloadable, so the old code sees
+-- exactly the state it would have written itself.
+UPDATE event e
+   SET export_zip_ready = EXISTS (
+         SELECT 1 FROM export_job j
+          WHERE j.event_id = e.id AND j.type = 'zip'
+            AND j.status = 'done' AND j.epoch = e.export_epoch
+       ),
+       export_html_ready = EXISTS (
+         SELECT 1 FROM export_job j
+          WHERE j.event_id = e.id AND j.type = 'html'
+            AND j.status = 'done' AND j.epoch = e.export_epoch
+       )
+ WHERE e.export_released_at IS NOT NULL;
+
+ALTER TABLE export_job RENAME COLUMN epoch TO release_seq;
+
+-- The old code treats release_seq as a non-negative per-job counter; the -1 retirement sentinel
+-- has no meaning there, so floor it back to 0.
+UPDATE export_job SET release_seq = 0 WHERE release_seq < 0;
+
+ALTER TABLE event DROP COLUMN export_epoch;

backend/migrations/014_export_epoch.up.sql

@@ -0,0 +1,86 @@
+-- Export generation, unified.
+--
+-- ⚠ ROLLBACK RUNBOOK. This is the repo's first DESTRUCTIVE migration (it DROPs two columns). The
+-- previous image will NOT boot against this schema: sqlx runs migrations before serving and errors
+-- with VersionMissing on an unknown version, so you get a crash loop, not a degraded service.
+-- To roll back to the previous release you must run 014_export_epoch.down.sql BY HAND FIRST, then
+-- deploy the old image. The down migration re-derives the old ready flags from the epoch state, so
+-- no keepsake is lost.
+--
+-- Before this migration, "which generation of the keepsake is current?" had no single answer.
+-- It was assembled at runtime from three separately-written pieces of state across two tables:
+--   * event.export_released_at   — a release marker with NO identity (you cannot ask *which* release)
+--   * export_job.release_seq     — a per-row counter, in a different table, bumped in a different statement
+--   * event.export_{zip,html}_ready — a CACHED COPY of the derivation of the other two
+-- Keeping those three in agreement took ~10 hand-written guards, and every guard was a repair of the
+-- same missing invariant. Three consecutive review rounds each found another path that slipped through.
+--
+-- This replaces all of it with ONE authority:
+--
+--   event.export_epoch — a monotonic counter bumped in the SAME UPDATE as any change to
+--                        export_released_at (release and reopen are its only writers).
+--   export_job.epoch   — a COPY of event.export_epoch taken when the job was enqueued.
+--                        NEVER independently incremented.
+--
+-- The single invariant, which replaces the entire proof:
+--
+--   An export is downloadable IFF
+--       event.export_released_at IS NOT NULL
+--   AND export_job.epoch = event.export_epoch
+--   AND export_job.status = 'done'
+--
+-- Readiness is therefore DERIVED, never stored — so it cannot drift, and no worker can set it.
+-- A worker holding a dead epoch is INERT BY CONSTRUCTION: anything it writes is invisible to every
+-- reader, with no guard involved. Losing a race can no longer corrupt state; it can only waste work.
+--
+-- Crucially, epoch equality is checked on the SAME ROW the worker updates (export_job), never via a
+-- cross-table EXISTS. That matters: under READ COMMITTED, when an UPDATE blocks on a row lock and the
+-- blocker commits, Postgres re-evaluates the WHERE against the *updated target row* but answers
+-- subqueries on OTHER tables from the statement's ORIGINAL snapshot. The old cross-row guard
+-- (`EXISTS (SELECT 1 FROM event WHERE ... export_released_at IS NOT NULL)`) was unsound for exactly
+-- that reason — it could admit a claim against an already-reopened event while RETURNING the
+-- post-bump seq. A same-row `epoch = $n` predicate is re-evaluated correctly by EPQ.
+
+ALTER TABLE event ADD COLUMN export_epoch BIGINT NOT NULL DEFAULT 0;
+
+-- A currently-released event's live generation becomes epoch 1.
+UPDATE event SET export_epoch = 1 WHERE export_released_at IS NOT NULL;
+
+-- The per-job counter becomes a plain copy of the event epoch it was enqueued for.
+ALTER TABLE export_job RENAME COLUMN release_seq TO epoch;
+
+-- Carry the OLD notion of "downloadable" across exactly: a job the old model considered ready
+-- (released + done + its ready flag) adopts the event's live epoch. Everything else is retired to
+-- -1, which can never equal a non-negative event.export_epoch, so it is inert forever.
+UPDATE export_job j
+   SET epoch = CASE
+         WHEN e.export_released_at IS NOT NULL
+          AND j.status = 'done'
+          AND ((j.type = 'zip'  AND e.export_zip_ready)
+            OR (j.type = 'html' AND e.export_html_ready))
+         THEN e.export_epoch
+         ELSE -1
+       END
+  FROM event e
+ WHERE e.id = j.event_id;
+
+-- The duplicated derivation. Gone — along with the whole class of bugs where a stale worker
+-- resurrected it, or where it disagreed with the job row it was supposed to summarise.
+ALTER TABLE event DROP COLUMN export_zip_ready;
+ALTER TABLE event DROP COLUMN export_html_ready;
+
+-- The ONE definition of "the current generation". Every reader goes through this, so readiness and
+-- the file path are resolved in a SINGLE read — closing the download-path TOCTOU where the ready
+-- flag was checked in one query and file_path fetched in another (a reopen between the two served a
+-- keepsake that should have 404'd).
+CREATE VIEW export_current AS
+SELECT j.event_id,
+       j.type,
+       j.status,
+       j.progress_pct,
+       j.file_path,
+       j.epoch
+  FROM export_job j
+  JOIN event e ON e.id = j.event_id
+ WHERE e.export_released_at IS NOT NULL   -- implied by the epoch match; kept as an assertion
+   AND j.epoch = e.export_epoch;

backend/migrations/015_raise_upload_rate.down.sql

@@ -0,0 +1,3 @@
+-- Revert the default upload rate to 10/hour for installs still on the raised
+-- default (preserves any explicit admin override at another value).
+UPDATE config SET value = '10' WHERE key = 'upload_rate_per_hour' AND value = '100';

backend/migrations/015_raise_upload_rate.up.sql

@@ -0,0 +1,10 @@
+-- Raise the default per-guest upload rate from 10/hour to 100/hour.
+--
+-- Rationale: guests routinely upload a burst of 10-20 photos at once (phone
+-- multi-select). At the old default of 10/hour a real guest's first burst was
+-- throttled — surfaced by the 2026-07-18 load test. 100/hour comfortably covers
+-- several bursts across an event while still bounding abuse.
+--
+-- Only bump installs still on the old default; an admin who deliberately set a
+-- different value keeps it (migration 005 seeded 10; this UPDATE is scoped to '10').
+UPDATE config SET value = '100' WHERE key = 'upload_rate_per_hour' AND value = '10';

backend/migrations/016_display_derivative.down.sql

@@ -0,0 +1,28 @@
+-- Drop the view (frees the column dependency), remove the column, then restore the
+-- pre-016 view definition (matches migration 011).
+DROP VIEW IF EXISTS v_feed;
+ALTER TABLE upload DROP COLUMN display_path;
+
+CREATE VIEW v_feed AS
+SELECT
+    u.id,
+    u.event_id,
+    u.user_id,
+    usr.display_name             AS uploader_name,
+    usr.is_banned,
+    usr.uploads_hidden,
+    u.preview_path,
+    u.thumbnail_path,
+    u.mime_type,
+    u.caption,
+    u.created_at,
+    COUNT(DISTINCT l.user_id)    AS like_count,
+    COUNT(DISTINCT c.id)         AS comment_count
+FROM upload u
+JOIN "user" usr ON u.user_id = usr.id
+LEFT JOIN "like" l  ON l.upload_id = u.id
+LEFT JOIN comment c ON c.upload_id = u.id AND c.deleted_at IS NULL
+WHERE u.deleted_at IS NULL
+  AND usr.uploads_hidden = FALSE
+  AND usr.is_banned = FALSE
+GROUP BY u.id, usr.display_name, usr.is_banned, usr.uploads_hidden;

backend/migrations/016_display_derivative.up.sql

@@ -0,0 +1,34 @@
+-- Display derivative: a big-screen-quality image (~2048px long edge) for the diashow.
+-- The 800px `preview_path` is sized for phone feeds (data saver); upscaled on a projector
+-- it looks soft. The diashow uses `display_path` instead — bounded in size (safe to decode
+-- on weak kiosk hardware) yet sharp on 1080p/4K. NULL until the compression worker (or the
+-- one-time backfill) generates it; consumers fall back to the original when absent.
+ALTER TABLE upload ADD COLUMN display_path TEXT;
+
+-- Recreate (not CREATE OR REPLACE, which only allows appending columns at the end) so the
+-- new column can sit alongside preview_path/thumbnail_path.
+DROP VIEW IF EXISTS v_feed;
+CREATE VIEW v_feed AS
+SELECT
+    u.id,
+    u.event_id,
+    u.user_id,
+    usr.display_name             AS uploader_name,
+    usr.is_banned,
+    usr.uploads_hidden,
+    u.preview_path,
+    u.thumbnail_path,
+    u.display_path,
+    u.mime_type,
+    u.caption,
+    u.created_at,
+    COUNT(DISTINCT l.user_id)    AS like_count,
+    COUNT(DISTINCT c.id)         AS comment_count
+FROM upload u
+JOIN "user" usr ON u.user_id = usr.id
+LEFT JOIN "like" l  ON l.upload_id = u.id
+LEFT JOIN comment c ON c.upload_id = u.id AND c.deleted_at IS NULL
+WHERE u.deleted_at IS NULL
+  AND usr.uploads_hidden = FALSE
+  AND usr.is_banned = FALSE
+GROUP BY u.id, usr.display_name, usr.is_banned, usr.uploads_hidden;

backend/migrations/017_join_ip_rate.down.sql

@@ -0,0 +1 @@
+DELETE FROM config WHERE key IN ('join_ip_rate_per_min', 'admin_login_rate_enabled');

backend/migrations/017_join_ip_rate.up.sql

@@ -0,0 +1,18 @@
+-- Per-IP flood ceiling for /join, and the `admin_login_rate_enabled` toggle that
+-- every prior migration forgot to seed.
+--
+-- Rationale: /join was throttled at 5 requests per 60s keyed on the client IP. At a
+-- venue every guest is behind one NAT, so the whole party shared a single bucket —
+-- 12 guests scanning the QR code within a few seconds meant 5 got in and 7 were
+-- turned away. The handler now keys the real anti-spam bucket per (ip, name), the
+-- same shape as `recover:{ip}:{name}`, and keeps only a loose per-IP ceiling to bound
+-- raw volume. 60/min comfortably covers a whole wedding arriving at once while still
+-- capping a flood from a single source.
+--
+-- `admin_login_rate_enabled` is read by auth::handlers::admin_login with a code
+-- default of `true`, but no migration ever inserted it, so it was invisible to the
+-- admin config UI and to the e2e reseed. Seed it explicitly.
+INSERT INTO config (key, value) VALUES
+    ('join_ip_rate_per_min',     '60'),
+    ('admin_login_rate_enabled', 'true')
+ON CONFLICT (key) DO NOTHING;

backend/migrations/018_derivatives_rev.down.sql

@@ -0,0 +1,2 @@
+DROP INDEX IF EXISTS idx_upload_derivatives_rev;
+ALTER TABLE upload DROP COLUMN IF EXISTS derivatives_rev;

backend/migrations/018_derivatives_rev.up.sql

@@ -0,0 +1,18 @@
+-- Track which revision of the derivative pipeline produced an upload's preview/display.
+--
+-- Rev 1 applies the EXIF orientation tag. Everything generated before it decoded the raw
+-- sensor pixels and re-encoded to JPEG (which writes no EXIF), so every portrait phone photo
+-- was stored sideways in the feed preview, the diashow display and the keepsake — while the
+-- untouched original still rendered upright.
+--
+-- Existing rows default to 0 so the startup backfill can find and re-generate them exactly
+-- once; bump the constant in services/compression.rs if the pipeline ever changes again.
+ALTER TABLE upload ADD COLUMN IF NOT EXISTS derivatives_rev SMALLINT NOT NULL DEFAULT 0;
+
+-- Only image derivatives are affected — video thumbnails are extracted by ffmpeg, which
+-- already honours the rotation matrix. Mark them current so the backfill skips them.
+UPDATE upload SET derivatives_rev = 1 WHERE mime_type NOT LIKE 'image/%';
+
+CREATE INDEX IF NOT EXISTS idx_upload_derivatives_rev
+    ON upload (derivatives_rev)
+    WHERE deleted_at IS NULL;

backend/migrations/019_recover_ip_rate.down.sql

@@ -0,0 +1 @@
+DELETE FROM config WHERE key = 'recover_ip_rate_per_min';

backend/migrations/019_recover_ip_rate.up.sql

@@ -0,0 +1,19 @@
+-- Per-IP flood ceiling for /recover, mirroring the one migration 017 added for /join.
+--
+-- Rationale: /recover is keyed `recover:{ip}:{name}` at 5 per 15 minutes. That is the
+-- right shape for its actual job — stopping someone who knows a display name (they are
+-- visible on the feed) from burning the victim's 3-strike PIN counter and locking them
+-- out repeatedly. But the name is attacker-chosen, so cycling names mints a fresh bucket
+-- every time and the per-IP cost is unbounded.
+--
+-- Behind that limiter sits a cost-12 bcrypt verify, including an UNCONDITIONAL throwaway
+-- verify for names that don't exist — deliberately, to close a timing oracle. So an
+-- unknown name is the cheapest possible way to make the server do ~200ms of hashing.
+-- Without a ceiling, one client can saturate the box's CPU with a name generator.
+--
+-- 30/min is far above any real recovery attempt (a guest tries their PIN a handful of
+-- times) while capping a name-cycling flood. The per-(ip, name) bucket is unchanged and
+-- remains the anti-guessing control.
+INSERT INTO config (key, value) VALUES
+    ('recover_ip_rate_per_min', '30')
+ON CONFLICT (key) DO NOTHING;

backend/migrations/020_social_rate.down.sql

@@ -0,0 +1 @@
+DELETE FROM config WHERE key IN ('social_rate_per_min', 'social_rate_enabled');

backend/migrations/020_social_rate.up.sql

@@ -0,0 +1,16 @@
+-- Per-user rate limit for social writes (likes, comments, comment deletions).
+--
+-- These were the only writes in the app with no limit at all. Every other mutating
+-- path -- upload, join, recover, export, admin login -- carries one; social.rs
+-- carried none, so the coverage was asymmetric rather than deliberately open.
+--
+-- Severity is genuinely low for an invited-guest event, and the amplification worry
+-- turned out to be contained: a like fans an SSE broadcast to ~100 clients, but the
+-- export regeneration it could otherwise trigger is debounced (REGEN_DEBOUNCE 20s)
+-- and superseded workers are inert. So this closes the gap for symmetry, not urgency,
+-- and the ceiling is set high enough that no real guest will ever meet it -- a
+-- double-tapping enthusiast at a wedding is not the thing being defended against.
+INSERT INTO config (key, value) VALUES
+    ('social_rate_per_min',  '120'),
+    ('social_rate_enabled',  'true')
+ON CONFLICT (key) DO NOTHING;

backend/migrations/021_hashtag_counts_respect_bans.down.sql

@@ -0,0 +1,13 @@
+-- Restore the pre-021 definition (no ban/hide filtering) exactly as 004 created it.
+DROP VIEW IF EXISTS v_hashtag_counts;
+
+CREATE VIEW v_hashtag_counts AS
+SELECT
+    h.event_id,
+    h.tag,
+    COUNT(uh.upload_id) AS upload_count
+FROM hashtag h
+JOIN upload_hashtag uh ON uh.hashtag_id = h.id
+JOIN upload u          ON u.id = uh.upload_id AND u.deleted_at IS NULL
+GROUP BY h.event_id, h.id, h.tag
+ORDER BY upload_count DESC;

backend/migrations/021_hashtag_counts_respect_bans.up.sql

@@ -0,0 +1,31 @@
+-- v_hashtag_counts: apply the same visibility rules as v_feed.
+--
+-- The chip row and the grid's tag picker are both fed by this view, but it has only ever
+-- filtered `u.deleted_at IS NULL`. Migration 011 added ban/hide filtering to the feed and
+-- never reached here, so the two disagreed about which uploads exist:
+--
+--   * A host bans a guest who posted 3 of the 12 `#tanz` photos. The chip keeps reading
+--     "#tanz 12"; tapping it returns 9. The count is presented as authoritative and is not.
+--   * A tag used ONLY by a banned or hidden guest stays in the chip row and in the tag
+--     picker as a selectable option that leads to an empty feed — a ghost filter that
+--     cannot be cleared because there is nothing wrong with it to see.
+--
+-- Bans are exactly the moment a host is watching these numbers to confirm the moderation
+-- took effect, so a stale count reads as "the ban didn't work".
+--
+-- Same predicate as v_feed (see 016_display_derivative.up.sql), joined through `user`.
+DROP VIEW IF EXISTS v_hashtag_counts;
+
+CREATE VIEW v_hashtag_counts AS
+SELECT
+    h.event_id,
+    h.tag,
+    COUNT(uh.upload_id) AS upload_count
+FROM hashtag h
+JOIN upload_hashtag uh ON uh.hashtag_id = h.id
+JOIN upload u          ON u.id = uh.upload_id AND u.deleted_at IS NULL
+JOIN "user" usr        ON usr.id = u.user_id
+WHERE usr.uploads_hidden = FALSE
+  AND usr.is_banned = FALSE
+GROUP BY h.event_id, h.id, h.tag
+ORDER BY upload_count DESC;

backend/migrations/022_client_upload_idempotency.down.sql

@@ -0,0 +1,2 @@
+DROP INDEX IF EXISTS upload_client_upload_id_key;
+ALTER TABLE upload DROP COLUMN IF EXISTS client_upload_id;

backend/migrations/022_client_upload_idempotency.up.sql

@@ -0,0 +1,25 @@
+-- Idempotency key for uploads, supplied by the client.
+--
+-- The failure this closes is the ordinary one on a phone, not an exotic race: the server
+-- receives the body, validates it, commits the row, and the response is lost on the way back
+-- because the guest walked out of range or the AP dropped the connection. The client sees a
+-- network error with the blob still in hand, marks the item retryable, and re-sends it — both
+-- when the guest taps "Erneut" and automatically when the queue requeues on reconnect. Every
+-- attempt minted a fresh `Uuid::new_v4()` server-side, so the same photo landed in the gallery
+-- two or three times and was charged against the guest's storage quota each time.
+--
+-- The client already has a stable per-queue-item UUID, so it costs nothing to send. NULL is
+-- allowed and unconstrained: uploads that predate this column, and any client that doesn't send
+-- one, keep working exactly as before.
+ALTER TABLE upload ADD COLUMN client_upload_id UUID;
+
+-- Partial rather than a plain UNIQUE. Postgres would tolerate the NULLs either way, but indexing
+-- only the rows that carry a key keeps it small and states the rule exactly: uniqueness applies
+-- where a key exists, and nowhere else.
+--
+-- Scoped globally rather than per user or per event. The key is a client-generated v4 UUID, so a
+-- collision between two different photos is not a real possibility, and a single-column index
+-- means the uniqueness check cannot be wrong about which event or user a retry belongs to.
+CREATE UNIQUE INDEX upload_client_upload_id_key
+    ON upload (client_upload_id)
+    WHERE client_upload_id IS NOT NULL;

backend/migrations/023_derivative_attempts.down.sql

@@ -0,0 +1,3 @@
+DROP INDEX IF EXISTS idx_upload_derivative_backfill;
+ALTER TABLE upload DROP COLUMN IF EXISTS derivative_last_error;
+ALTER TABLE upload DROP COLUMN IF EXISTS derivative_attempts;

backend/migrations/023_derivative_attempts.up.sql

@@ -0,0 +1,23 @@
+-- Bound how many times a permanently-failing upload can be re-processed.
+--
+-- Without this, one poisoned row is an outage. The upload row is committed BEFORE compression
+-- starts, `derivatives_rev` defaults to 0, and `set_derivatives_rev` only runs on success — so
+-- a row whose processing kills the container survives at rev 0, the unconditional startup
+-- backfill re-selects it on the next boot, and `restart: unless-stopped` turns that into an
+-- infinite kill loop. Every restart also drops every SSE stream and truncates every in-flight
+-- upload. That was reachable via a single large PNG (see services/compression.rs), but the
+-- shape is general: any input that can kill or hang the worker repeats forever.
+--
+-- The counter is incremented WRITE-AHEAD, before the work is attempted, because the failure
+-- mode being defended against is a SIGKILL — no error is returned, no handler runs, no Drop
+-- fires. A counter bumped in an error path increments zero times per crash and changes nothing.
+ALTER TABLE upload ADD COLUMN IF NOT EXISTS derivative_attempts SMALLINT NOT NULL DEFAULT 0;
+
+-- Last failure text, so a row that has given up can be diagnosed without reproducing it.
+-- Nothing reads this in code; it exists for the operator.
+ALTER TABLE upload ADD COLUMN IF NOT EXISTS derivative_last_error TEXT;
+
+-- Serves the backfill selection, which now filters on both columns.
+CREATE INDEX IF NOT EXISTS idx_upload_derivative_backfill
+    ON upload (derivatives_rev, derivative_attempts)
+    WHERE deleted_at IS NULL;

backend/migrations/024_feed_scalar_counts.down.sql

@@ -0,0 +1,26 @@
+-- Restore the 016 definition verbatim.
+DROP VIEW IF EXISTS v_feed;
+CREATE VIEW v_feed AS
+SELECT
+    u.id,
+    u.event_id,
+    u.user_id,
+    usr.display_name             AS uploader_name,
+    usr.is_banned,
+    usr.uploads_hidden,
+    u.preview_path,
+    u.thumbnail_path,
+    u.display_path,
+    u.mime_type,
+    u.caption,
+    u.created_at,
+    COUNT(DISTINCT l.user_id)    AS like_count,
+    COUNT(DISTINCT c.id)         AS comment_count
+FROM upload u
+JOIN "user" usr ON u.user_id = usr.id
+LEFT JOIN "like" l  ON l.upload_id = u.id
+LEFT JOIN comment c ON c.upload_id = u.id AND c.deleted_at IS NULL
+WHERE u.deleted_at IS NULL
+  AND usr.uploads_hidden = FALSE
+  AND usr.is_banned = FALSE
+GROUP BY u.id, usr.display_name, usr.is_banned, usr.uploads_hidden;

backend/migrations/024_feed_scalar_counts.up.sql

@@ -0,0 +1,55 @@
+-- Make a feed page cost a page, not the whole event.
+--
+-- The previous definition (016) computed like_count/comment_count with LEFT JOINs and a
+-- GROUP BY. Postgres CAN push the `event_id = $1` qual and the keyset predicate through the
+-- view — verified with EXPLAIN, it uses idx_upload_event_created_id — but it CANNOT push
+-- ORDER BY ... LIMIT across a GroupAggregate. So every feed request aggregated every upload in
+-- the event (times its likes and comments) and only then sorted and took 21 rows. The cost
+-- grew with the event, not with the page, and page 1 — the most expensive one — is exactly
+-- what refreshFeedInPlace refetches on every completed upload, from every open feed in the
+-- venue.
+--
+-- Correlated scalar subqueries move the counts ABOVE the Limit in the plan: they are evaluated
+-- once per returned row, so 21 index lookups instead of a full aggregation.
+--
+-- The rewrite is EXACTLY equivalent, not merely close:
+--   * "like" is keyed (upload_id, user_id), so COUNT(DISTINCT l.user_id) == count(*).
+--   * comment.id is the primary key, so COUNT(DISTINCT c.id) == count(*).
+--   * one row per upload either way — the GROUP BY was on u.id.
+-- Column names, order and types are unchanged (count(*) and COUNT(DISTINCT ...) are both
+-- bigint), so no Rust code changes.
+--
+-- No new index needed: idx_like_upload plus the (upload_id, user_id) PK serve the like
+-- subquery, and idx_comment_upload ... WHERE deleted_at IS NULL matches the comment
+-- subquery's predicate exactly.
+--
+-- One thing a future editor needs to know: the hashtag-filtered feed joins upload_hashtag
+-- against this view. That was safe before only because the GROUP BY collapsed the join
+-- fan-out; it is safe now because the view is one row per upload and upload_hashtag is keyed
+-- (upload_id, hashtag_id) with a single tag filtered. Adding a second tag filter would need
+-- fresh thought.
+
+-- Not CASCADE: if something ever comes to depend on this view, the migration should fail
+-- loudly rather than silently drop it.
+DROP VIEW IF EXISTS v_feed;
+CREATE VIEW v_feed AS
+SELECT
+    u.id,
+    u.event_id,
+    u.user_id,
+    usr.display_name AS uploader_name,
+    usr.is_banned,
+    usr.uploads_hidden,
+    u.preview_path,
+    u.thumbnail_path,
+    u.display_path,
+    u.mime_type,
+    u.caption,
+    u.created_at,
+    (SELECT count(*) FROM "like" l WHERE l.upload_id = u.id)                           AS like_count,
+    (SELECT count(*) FROM comment c WHERE c.upload_id = u.id AND c.deleted_at IS NULL) AS comment_count
+FROM upload u
+JOIN "user" usr ON u.user_id = usr.id
+WHERE u.deleted_at IS NULL
+  AND usr.uploads_hidden = FALSE
+  AND usr.is_banned = FALSE;

backend/migrations/025_reserved_names_and_pin_decay.down.sql

@@ -0,0 +1,11 @@
+-- NOTE: the reserved-name rename in the up migration is NOT reversible. The original names
+-- are not recorded anywhere, and reversing it would in any case re-create the state that
+-- bricked admin login. Rolling back the schema does not roll back that data change.
+DELETE FROM config WHERE key IN (
+    'recover_name_rate_per_15min',
+    'pin_reset_ip_rate_per_min',
+    'upload_edit_rate_per_min',
+    'upload_edit_rate_enabled'
+);
+
+ALTER TABLE "user" DROP COLUMN IF EXISTS last_failed_pin_at;

backend/migrations/025_reserved_names_and_pin_decay.up.sql

@@ -0,0 +1,70 @@
+-- Two independent auth defects that share a migration because they share a table.
+
+-- 1. RESERVED NAMES — free any guest squatting on a name the admin path used to depend on.
+--
+-- Migration 007 made display_name unique per event case-insensitively, and `join` had no
+-- reserved-name guard. So any guest could join as "admin"/"Admin"/"ADMIN" before the operator's
+-- first admin login; admin_login then looked its user up BY NAME, missed (wrong role), fell
+-- through to creating "Admin", violated that unique index, and returned a 500 — permanently,
+-- with no in-app recovery. Moderation, config and gallery release all gone, fixed only by SQL.
+--
+-- The real fix is in code (look the admin up by role, never by name — see auth/handlers.rs).
+-- This clears the state an already-deployed database may be carrying.
+--
+-- RENAMED, NEVER DELETED: the guest keeps their uploads, their PIN and their session. Only
+-- non-admin rows are touched — a real admin row named "Admin" is the expected state.
+-- Two guards that are not optional, because this statement runs INSIDE the migration
+-- transaction on boot and a failure here exits the process — `restart: unless-stopped` then
+-- turns it into a crash loop with no in-app recovery. That is a strictly worse version of the
+-- lockout this migration exists to clean up after.
+--
+--   * role = 'guest', not role <> 'admin'. The enum also has 'host' (001), and hosts are
+--     promoted from guests at runtime — so <> 'admin' renamed a legitimately promoted staff
+--     member whose name happens to be "Host".
+--   * NOT EXISTS. The target name is derived, not unique: `idx_user_event_name_ci` (007) is a
+--     UNIQUE index on (event_id, lower(display_name)), and nothing stopped a second guest from
+--     having already joined as exactly "Admin (a1b2c3d4)" — the old code had no reserved-name
+--     guard and the join response hands each guest their own id. Rare, but the cost of losing
+--     that bet is the whole event.
+--
+-- A row that collides is simply left alone: `create_admin_user` already handles a name clash by
+-- falling back to `Admin-<8hex>`, and `admin_login` no longer resolves by name at all, so this
+-- cleanup is convenience rather than load-bearing.
+UPDATE "user" u
+   SET display_name = u.display_name || ' (' || left(u.id::text, 8) || ')'
+ WHERE u.role = 'guest'
+   AND lower(u.display_name) IN ('admin', 'administrator', 'host', 'eventsnap')
+   AND NOT EXISTS (
+        SELECT 1 FROM "user" x
+         WHERE x.event_id = u.event_id
+           AND lower(x.display_name) = lower(u.display_name || ' (' || left(u.id::text, 8) || ')')
+   );
+
+-- 2. PIN LOCKOUT DECAY.
+--
+-- failed_pin_attempts only ever cleared on a successful recovery or after a lockout expired, so
+-- honest typos accumulated across days: a guest who fat-fingered their PIN twice last night
+-- arrives today already two-thirds of the way to being locked out. With the threshold now
+-- raised (see below) a decay window is what keeps that raise safe rather than merely lenient.
+ALTER TABLE "user" ADD COLUMN IF NOT EXISTS last_failed_pin_at TIMESTAMPTZ;
+
+-- Rate-limit knobs introduced with this release.
+--
+-- recover_name_rate_per_15min (4, was a hardcoded 5): the per-(IP, name) ceiling. It MUST stay
+-- below the account-lock threshold, which is the whole defect — at 5-per-IP against a 3-strike
+-- lock, three requests from one IP locked any guest whose name is visible on the feed, every 15
+-- minutes, forever. The lock threshold moves to 12 in code, so locking a victim now needs at
+-- least three distinct sources while an honest guest never comes close.
+--
+-- pin_reset_ip_rate_per_min (30): /recover/request was the one unauthenticated endpoint with no
+-- per-IP ceiling at all — /join got one in 017 and /recover in 019, and this third one was
+-- simply missed. Its per-name key is attacker-chosen, so cycling names minted a fresh bucket
+-- every time and the per-IP cost was unbounded.
+--
+-- upload_edit_rate_per_min (30): PATCH /upload/{id} had no rate limit of any kind.
+INSERT INTO config (key, value) VALUES
+    ('recover_name_rate_per_15min', '4'),
+    ('pin_reset_ip_rate_per_min',   '30'),
+    ('upload_edit_rate_per_min',    '30'),
+    ('upload_edit_rate_enabled',    'true')
+ON CONFLICT (key) DO NOTHING;

backend/scripts/rehearse-014.sh

@@ -0,0 +1,195 @@
+#!/usr/bin/env bash
+#
+# Dress rehearsal for migration 014 (export_epoch) — the repo's first DESTRUCTIVE migration.
+#
+# 014 DROPs event.export_zip_ready / export_html_ready and rewrites export_job.release_seq into an
+# epoch. The dangerous part is not the DDL, it's the BACKFILL: it has to carry the old notion of
+# "downloadable" across exactly. Get it wrong and a released event's keepsake silently 404s for
+# every guest, on a dataset you cannot re-create.
+#
+# This script proves the backfill preserves downloadability, against a scratch copy of a REAL dump:
+#
+#   ./rehearse-014.sh /path/to/prod-dump.sql     # rehearse against production data
+#   ./rehearse-014.sh                            # synthetic: build a pre-014 DB covering every case
+#
+# It asserts:
+#   1. up:   {(event,type) downloadable BEFORE} == {(event,type) downloadable AFTER}
+#   2. down: the old ready flags come back identical  (so a rollback is actually a rollback)
+#   3. up again: still identical                      (so a roll-forward after a rollback is safe)
+#
+# It NEVER touches your real database. Everything runs in a throwaway container.
+#
+# NOTE ON ROLLBACK (see the runbook header in 014_export_epoch.up.sql): sqlx runs migrations before
+# serving and errors with VersionMissing on an unknown version, so the PREVIOUS image will not boot
+# against the 014 schema — it crash-loops. Rolling back means running 014_export_epoch.down.sql BY
+# HAND FIRST, then deploying the old image. Assertion 2 is what makes that safe. Rehearse it before
+# you need it, not while the party is happening.
+
+set -euo pipefail
+
+DUMP="${1:-}"
+MIG_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../migrations" && pwd)"
+CONTAINER="eventsnap-rehearse-014"
+PGPASSWORD="rehearse"
+DB="eventsnap_rehearsal"
+
+cleanup() { docker rm -f "$CONTAINER" > /dev/null 2>&1 || true; }
+trap cleanup EXIT
+cleanup
+
+echo "▸ Starting a throwaway postgres:16 (nothing here touches your real DB)…"
+docker run --rm -d --name "$CONTAINER" \
+  -e POSTGRES_PASSWORD="$PGPASSWORD" -e POSTGRES_DB="$DB" \
+  postgres:16-alpine > /dev/null
+
+psql() { docker exec -i -e PGPASSWORD="$PGPASSWORD" "$CONTAINER" psql -U postgres -d "$DB" -v ON_ERROR_STOP=1 "$@"; }
+
+for _ in $(seq 1 30); do
+  if docker exec "$CONTAINER" pg_isready -U postgres > /dev/null 2>&1; then break; fi
+  sleep 1
+done
+
+if [[ -n "$DUMP" ]]; then
+  echo "▸ Restoring $DUMP …"
+  psql -q < "$DUMP"
+else
+  echo "▸ No dump given — building a synthetic pre-014 DB (migrations 001→013)…"
+  for f in "$MIG_DIR"/0[0-1][0-9]_*.up.sql; do
+    [[ "$(basename "$f")" == 014_* ]] && continue
+    psql -q < "$f"
+  done
+
+  # Every state the backfill has to classify. If 014 mishandles ANY of these, assertion 1 fails.
+  # Every state the backfill has to classify. export_job is UNIQUE (event_id, type), so each event
+  # has at most one job per type — the cases are distinguished by event, not by piling up rows.
+  #   A: released, both flags, both done  → both stay downloadable
+  #   B: released, ZIP flag only          → ZIP downloadable, HTML not (a half-built keepsake)
+  #   C: released, jobs done, NO flags    → NOT downloadable (a superseded worker's finished job:
+  #                                          the exact state the old ready-flag model used to leak)
+  #   D: never released, jobs done        → NOT downloadable (reopened, or built before release)
+  #   E: released, ZIP flag set but the job is FAILED/RUNNING → NOT downloadable (flag/job disagree,
+  #                                          which the old two-source model made representable at all)
+  echo "▸ Seeding: released+both, zip-only, done-but-stale, unreleased, flag/job-disagreement…"
+  psql -q <<'SQL'
+INSERT INTO event (id, slug, name, export_released_at, export_zip_ready, export_html_ready) VALUES
+  ('aaaaaaaa-0000-0000-0000-000000000001','ev-a','A', now(), TRUE,  TRUE),
+  ('aaaaaaaa-0000-0000-0000-000000000002','ev-b','B', now(), TRUE,  FALSE),
+  ('aaaaaaaa-0000-0000-0000-000000000003','ev-c','C', now(), FALSE, FALSE),
+  ('aaaaaaaa-0000-0000-0000-000000000004','ev-d','D', NULL,  FALSE, FALSE),
+  ('aaaaaaaa-0000-0000-0000-000000000005','ev-e','E', now(), TRUE,  TRUE);
+
+INSERT INTO export_job (event_id, type, status, progress_pct, file_path, release_seq)
+SELECT e.id, t::export_type, 'done'::export_status, 100, '/x/' || e.slug || '.' || t, 0
+  FROM event e CROSS JOIN (VALUES ('zip'),('html')) AS v(t);
+
+-- E: the flags claim ready, the jobs say otherwise. Old model required BOTH, so neither is
+-- downloadable — the migration must not "trust the flag" and resurrect them.
+UPDATE export_job SET status = 'failed',  file_path = NULL, progress_pct = 40
+ WHERE event_id = 'aaaaaaaa-0000-0000-0000-000000000005' AND type = 'zip';
+UPDATE export_job SET status = 'running', file_path = NULL, progress_pct = 70
+ WHERE event_id = 'aaaaaaaa-0000-0000-0000-000000000005' AND type = 'html';
+SQL
+fi
+
+echo "▸ Snapshotting what is downloadable under the OLD model…"
+psql -q <<'SQL'
+CREATE TABLE _rehearsal_before AS
+SELECT j.event_id, j.type
+  FROM export_job j JOIN event e ON e.id = j.event_id
+ WHERE e.export_released_at IS NOT NULL
+   AND j.status = 'done'
+   AND ((j.type = 'zip' AND e.export_zip_ready) OR (j.type = 'html' AND e.export_html_ready));
+
+-- For assertion 2: the exact flags a rollback has to reproduce.
+CREATE TABLE _rehearsal_flags AS
+SELECT id, export_zip_ready, export_html_ready FROM event;
+SQL
+
+before=$(psql -tAc "SELECT count(*) FROM _rehearsal_before")
+echo "  → $before (event,type) pair(s) downloadable before."
+
+# The assertion. A symmetric difference of zero means the backfill carried the old notion of
+# "downloadable" across EXACTLY: nothing gained (a stale keepsake resurrected), nothing lost (a
+# guest's keepsake silently 404s).
+assert_up_preserves() {
+  local label="$1" diff
+  diff=$(psql -tAc "
+    SELECT count(*) FROM (
+      (SELECT event_id, type FROM _rehearsal_before
+        EXCEPT SELECT event_id, type FROM export_current WHERE status = 'done')
+      UNION ALL
+      (SELECT event_id, type FROM export_current WHERE status = 'done'
+        EXCEPT SELECT event_id, type FROM _rehearsal_before)
+    ) d")
+  if [[ "$diff" != "0" ]]; then
+    echo "✗ FAIL ($label): $diff (event,type) pair(s) changed downloadability across the migration."
+    psql -c "
+      (SELECT 'LOST — guests can no longer download this' AS problem, event_id, type FROM _rehearsal_before
+        EXCEPT ALL SELECT 'LOST — guests can no longer download this', event_id, type FROM export_current WHERE status='done')
+      UNION ALL
+      (SELECT 'GAINED — a stale keepsake became downloadable', event_id, type FROM export_current WHERE status='done'
+        EXCEPT ALL SELECT 'GAINED — a stale keepsake became downloadable', event_id, type FROM _rehearsal_before)"
+    exit 1
+  fi
+  echo "✓ $label: downloadability preserved exactly ($before pair(s))."
+}
+
+echo "▸ Applying 014 (up)…"
+psql -q < "$MIG_DIR/014_export_epoch.up.sql"
+assert_up_preserves "up"
+
+echo "▸ Applying 014 (down) — the rollback path…"
+psql -q < "$MIG_DIR/014_export_epoch.down.sql"
+
+# The down migration is an inverse UP TO DRIFT, not a bit-exact inverse — deliberately.
+#
+# The old model let a ready flag disagree with its job row (flag TRUE over a running/failed job):
+# the flag was a CACHED copy of a derivation, and keeping a cache in agreement with its source
+# across concurrent workers is precisely what it kept failing at. The down migration re-derives the
+# flags from the epoch state, so such a pair comes back FALSE. That HEALS the drift rather than
+# faithfully restoring corruption, and it costs nothing: a flag over a non-done job had no file to
+# serve (file_path is NULL until the worker finishes), so the old code 404'd on it anyway.
+#
+# What a rollback must NOT do is drop a flag for a keepsake that was genuinely downloadable
+# (flag set AND the job actually done). That is the assertion.
+lost=$(psql -tAc "
+  SELECT count(*) FROM _rehearsal_before b
+   WHERE NOT EXISTS (
+     SELECT 1 FROM event e
+      WHERE e.id = b.event_id
+        AND ((b.type = 'zip' AND e.export_zip_ready) OR (b.type = 'html' AND e.export_html_ready)))")
+if [[ "$lost" != "0" ]]; then
+  echo "✗ FAIL (down): $lost downloadable keepsake(s) lost their ready flag — the rollback is LOSSY."
+  psql -c "
+    SELECT b.event_id, b.type, 'was downloadable, flag not restored' AS problem
+      FROM _rehearsal_before b
+     WHERE NOT EXISTS (
+       SELECT 1 FROM event e
+        WHERE e.id = b.event_id
+          AND ((b.type = 'zip' AND e.export_zip_ready) OR (b.type = 'html' AND e.export_html_ready)))"
+  exit 1
+fi
+echo "✓ down: every downloadable keepsake kept its flag — the old image sees a working state."
+
+healed=$(psql -tAc "
+  SELECT count(*) FROM event e JOIN _rehearsal_flags f ON f.id = e.id
+   WHERE (e.export_zip_ready, e.export_html_ready) IS DISTINCT FROM (f.export_zip_ready, f.export_html_ready)")
+if [[ "$healed" != "0" ]]; then
+  echo "  ℹ $healed event(s) came back with a CLEARED flag that had drifted from its job row."
+  echo "    Not a loss — those had no file to serve. The rollback normalises them; the old code"
+  echo "    will rebuild on the next release. Listing them so the behaviour is not a surprise:"
+  psql -c "SELECT e.id, f.export_zip_ready AS was_zip, e.export_zip_ready AS now_zip,
+                  f.export_html_ready AS was_html, e.export_html_ready AS now_html
+             FROM event e JOIN _rehearsal_flags f ON f.id = e.id
+            WHERE (e.export_zip_ready, e.export_html_ready)
+                  IS DISTINCT FROM (f.export_zip_ready, f.export_html_ready)"
+fi
+
+echo "▸ Re-applying 014 (up) — roll forward after a rollback…"
+psql -q < "$MIG_DIR/014_export_epoch.up.sql"
+assert_up_preserves "up (after rollback)"
+
+echo
+echo "✓ Rehearsal passed. 014 is safe to deploy against this dataset."
+[[ -z "$DUMP" ]] && echo "  (synthetic data — re-run with a real pg_dump before you deploy for real)"
+exit 0

backend/src/auth/handlers.rs

@@ -1,11 +1,12 @@
 use std::time::Duration;
 
-use axum::extract::State;
-use axum::http::{HeaderMap, StatusCode};
 use axum::Json;
+use axum::extract::{ConnectInfo, State};
+use axum::http::{HeaderMap, StatusCode};
 use chrono::Utc;
 use rand::Rng;
 use serde::{Deserialize, Serialize};
+use std::net::SocketAddr;
 use uuid::Uuid;
 
 use crate::auth::jwt;
@@ -15,10 +16,61 @@ use crate::models::event::Event;
 use crate::models::session::Session;
 use crate::models::user::{User, UserRole};
 use crate::services::config;
-use crate::services::password;
 use crate::services::rate_limiter::client_ip;
 use crate::state::AppState;
 
+/// Names a guest may not take.
+///
+/// Defence in depth only. The real fix for the admin-lockout defect is that `admin_login` now
+/// resolves its user by ROLE rather than by name (see `User::find_admin_for_event`), which is
+/// why homoglyph and zero-width bypasses of this list are not a concern: the name is no longer
+/// load-bearing for anything. What this buys is that a guest cannot impersonate the host in the
+/// feed's byline, and that "Admin" stays available for the admin row.
+const RESERVED_DISPLAY_NAMES: &[&str] = &["admin", "administrator", "host", "eventsnap"];
+
+fn is_reserved_display_name(name: &str) -> bool {
+    let name = name.trim().to_lowercase();
+    RESERVED_DISPLAY_NAMES.contains(&name.as_str())
+}
+
+/// Trim and bounds-check a display name.
+///
+/// Shared by `join`, `recover` and `request_pin_reset` so the length check happens BEFORE the
+/// name is used to build a rate-limiter key. It was inline in `join` only, so on the other two
+/// endpoints `format!("...:{ip}:{name_key}")` allocated from an unbounded, attacker-chosen
+/// string and stored it in a HashMap pruned once an hour with a 24 h ceiling — turning the
+/// limiter itself into the memory-exhaustion primitive it exists to prevent.
+fn validate_display_name(raw: &str) -> Result<&str, AppError> {
+    let name = raw.trim();
+    let chars = name.chars().count();
+    if chars == 0 || chars > 50 {
+        return Err(AppError::BadRequest(
+            "Name muss zwischen 1 und 50 Zeichen lang sein.".into(),
+        ));
+    }
+    // No control characters. NUL is the hard requirement — Postgres rejects 0x00 in TEXT with a
+    // 500, so catching it here turns an internal error into a clean 400 — but the rest matter
+    // too, and for reasons beyond tidiness:
+    //
+    //  * Newlines make the name a LOG INJECTION vector. Several 4xx messages interpolate it
+    //    ("Der Name \"X\" ist bereits vergeben.") and those are logged; a name carrying a
+    //    newline plus a plausible timestamp prefix lets two unauthenticated requests forge
+    //    entries in the only forensic record an unattended event has. `error.rs` escapes on the
+    //    way out as well — this is the other half, and the half that keeps the forged text out
+    //    of the database and out of the feed byline in the first place.
+    //  * A bare CR or a bidi override renders as a name that is not what was typed, in the feed,
+    //    the host dashboard's moderation list and the keepsake.
+    //
+    // Deliberately NOT a whitelist: guests have accents, emoji and non-Latin scripts in their
+    // names, and rejecting those would be worse than the problem.
+    if name.chars().any(|c| c.is_control()) {
+        return Err(AppError::BadRequest(
+            "Name enthält ungültige Zeichen.".into(),
+        ));
+    }
+    Ok(name)
+}
+
 #[derive(Deserialize)]
 pub struct JoinRequest {
     pub display_name: String,
@@ -34,44 +86,58 @@ pub struct JoinResponse {
 
 pub async fn join(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<JoinRequest>,
 ) -> Result<(StatusCode, Json<JoinResponse>), AppError> {
-    let ip = client_ip(&headers, "unknown");
-    let rate_limits_on = config::get_bool(&state.pool, "rate_limits_enabled", true).await;
-    let join_rate_on = config::get_bool(&state.pool, "join_rate_enabled", true).await;
+    let ip = client_ip(&headers, &peer.ip().to_string());
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let join_rate_on = config::get_bool(&state.config_cache, "join_rate_enabled", true).await;
+
+    // Coarse per-IP flood ceiling. `/join` is pre-auth so there is no user to key on, and
+    // at a venue EVERY guest arrives from one public IP — a tight per-IP bucket meant the
+    // 6th person through the door was turned away by the 5 ahead of them. So the per-IP
+    // limit here only bounds raw volume; the real anti-spam bucket is per-name below.
+    // Cheap enough to run before validation, which keeps a flood of malformed bodies from
+    // being free.
     if rate_limits_on && join_rate_on {
-        // Short burst cap (typos / double-taps) AND a generous per-IP daily cap
-        // on account creation. The daily cap bounds mass account-minting (which
-        // otherwise resets the per-user upload budget, see the event-wide count
-        // quota in the upload handler) while staying well above a real ~100-guest
-        // venue sharing one NAT'd IP.
-        let burst_ok =
-            state.rate_limiter.check(format!("join:{ip}"), 5, Duration::from_secs(60));
-        let daily_ok = state
-            .rate_limiter
-            .check(format!("join_day:{ip}"), 200, Duration::from_secs(86_400));
-        if !burst_ok || !daily_ok {
+        let ip_ceiling = config::get_usize(&state.config_cache, "join_ip_rate_per_min", 60).await;
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("join_ip:{ip}"),
+            ip_ceiling,
+            Duration::from_secs(60),
+        ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }
 
-    let display_name = body.display_name.trim();
-    let name_chars = display_name.chars().count();
-    if name_chars == 0 || name_chars > 50 {
-        return Err(AppError::BadRequest(
-            "Name muss zwischen 1 und 50 Zeichen lang sein.".into(),
-        ));
+    let display_name = validate_display_name(&body.display_name)?;
+    if is_reserved_display_name(display_name) {
+        // 409, matching the name-taken response below, so the frontend's existing handling
+        // works unchanged. See RESERVED_DISPLAY_NAMES for why this exists.
+        return Err(AppError::Conflict(format!(
+            "Der Name \"{display_name}\" ist reserviert. Bitte wähle einen anderen."
+        )));
     }
-    // Postgres rejects 0x00 in TEXT columns with a 500. Catch it here so callers
-    // see a clean 400 instead of an internal error.
-    if display_name.contains('\0') {
-        return Err(AppError::BadRequest(
-            "Name enthält ungültige Zeichen.".into(),
-        ));
+
+    // Per-guest bucket, keyed like the `recover:{ip}:{name}` limiter below. This carries
+    // the original 5/60s anti-spam intent, but one guest retrying can no longer consume
+    // the allowance of everyone else sharing the venue's NAT.
+    if rate_limits_on && join_rate_on {
+        let name_key = display_name.to_lowercase();
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("join:{ip}:{name_key}"),
+            5,
+            Duration::from_secs(60),
+        ) {
+            return Err(AppError::TooManyRequests(
+                "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
     }
 
     let event = Event::find_or_create(
@@ -89,12 +155,23 @@ pub async fn join(
         )));
     }
 
-    // Generate a 6-digit PIN (≈20 bits vs the old ~13.3, so brute-forcing it
-    // against the 3-strike lockout is far harder).
-    let pin: String = format!("{:06}", rand::rng().random_range(0..1_000_000u32));
-    let pin_hash = password::hash(pin.clone(), 12).await?;
+    // Generate a 4-digit PIN
+    let pin: String = format!("{:04}", rand::rng().random_range(0..10000u32));
+    let pin_hash = hash_password(pin.clone(), 12).await?;
 
-    let user = User::create(&state.pool, event.id, display_name, &pin_hash).await?;
+    // The pre-check above is racy: two simultaneous joins with the same name can both
+    // pass it, and the DB's unique index then rejects the loser. Map that unique
+    // violation to the same clean 409 the pre-check returns, not a generic 500.
+    let user = match User::create(&state.pool, event.id, display_name, &pin_hash).await {
+        Ok(u) => u,
+        Err(sqlx::Error::Database(db)) if db.is_unique_violation() => {
+            return Err(AppError::Conflict(format!(
+                "Der Name \"{}\" ist bereits vergeben.",
+                display_name
+            )));
+        }
+        Err(e) => return Err(e.into()),
+    };
 
     let token = jwt::create_token(
         user.id,
@@ -120,6 +197,38 @@ pub async fn join(
     ))
 }
 
+/// Default for `recover_name_rate_per_15min` — wrong PINs allowed per (IP, name) per 15 min.
+/// Mirrors migration 023; kept here so the invariant below can be asserted in a test.
+const RECOVER_NAME_CEILING_DEFAULT: usize = 4;
+
+/// Hard ceiling on the CONFIGURED per-(IP, name) limit, whatever an operator sets.
+///
+/// The ordering `3 x ceiling <= PIN_LOCK_THRESHOLD` is the entire control that stops one source
+/// from locking a victim out: display names are public on the feed, so if a single IP can spend
+/// the whole lock threshold it can lock any guest it likes, repeatedly. That ordering was asserted
+/// in a comment and in a test — but the test pinned the DEFAULT constant, while the handler reads
+/// the config value, and `patch_config` accepted anything from 1 to 100_000. So an operator
+/// raising this key restored the exact DoS the tier ordering exists to prevent, silently.
+pub const RECOVER_NAME_CEILING_MAX: usize = (PIN_LOCK_THRESHOLD as usize) / 3;
+
+/// Wrong PINs, from ALL sources, before the ACCOUNT itself is locked for 15 minutes.
+///
+/// This was 3, which sat BELOW the per-(IP, name) ceiling of 5 — and that ordering, not the
+/// number, was the defect. Display names are public on the feed, so three requests from a single
+/// IP locked any guest out of their own account, repeatable every 15 minutes, indefinitely. The
+/// tier meant to protect a guest was the easiest way to attack them.
+///
+/// Raised deliberately far above the per-IP tier so the two do different jobs. The per-(IP, name)
+/// bucket is what stops a guesser, and it costs the ATTACKER. This tier is the last line against
+/// a DISTRIBUTED guesser, and it is the only one an attacker can turn on a victim — so reaching
+/// it must require at least three distinct sources inside the decay window.
+///
+/// Brute-force cost is unchanged: 12 attempts per 15 minutes is 48/hour against one account, so
+/// 10 000 four-digit PINs still take ~208 hours no matter how many IPs are used. An honest guest
+/// fat-fingering a 4-digit PIN never comes close, and `increment_failed_pin` now decays the
+/// streak after 15 minutes so yesterday's typos don't count toward today's.
+const PIN_LOCK_THRESHOLD: i16 = 12;
+
 #[derive(Deserialize)]
 pub struct RecoverRequest {
     pub display_name: String,
@@ -132,31 +241,126 @@ pub struct RecoverResponse {
     pub user_id: Uuid,
 }
 
+/// A real cost-12 bcrypt hash of a fixed dummy value, computed once and cached. Used
+/// to run a constant-time-ish verify on the "unknown display name" branch of
+/// [`recover`], so that branch costs the same as a real (user-exists) verify and can't
+/// be told apart by timing.
+fn dummy_pin_hash() -> &'static str {
+    static HASH: std::sync::OnceLock<String> = std::sync::OnceLock::new();
+    HASH.get_or_init(|| {
+        bcrypt::hash("eventsnap-dummy-not-a-real-pin", 12)
+            .expect("bcrypt hashing of a static dummy value cannot fail")
+    })
+}
+
+/// Run a bcrypt verify on the blocking pool.
+///
+/// bcrypt at cost 12 is ~200ms of deliberate CPU. Called inline on an async task it pins a
+/// tokio WORKER thread for that whole time, and the runtime only has one per core — so a
+/// flood of `/recover` or `/admin/login` attempts stalls every other request on the box,
+/// including the feed. Offloading moves that cost to the blocking pool, which is sized for
+/// exactly this and whose saturation degrades logins rather than the whole app.
+/// Process-wide ceiling on CONCURRENT bcrypt work.
+///
+/// bcrypt is deliberately expensive — ~250 ms of a core at cost 12, and this deployment's own
+/// runbook generates the admin hash at a higher cost than that. Every call is correctly on
+/// `spawn_blocking`, but tokio's blocking pool defaults to 512 threads, so "off the async
+/// runtime" is not the same as "bounded": enough concurrent hashes will preempt both async
+/// worker threads a 2 vCPU box gets, and uploads, feed and SSE stall behind them.
+///
+/// Three unauthenticated endpoints reach bcrypt — `/join` (hash), `/recover` (verify, including
+/// a deliberate throwaway verify for unknown names) and `/admin/login` (verify) — each with only
+/// a per-IP bucket in front, and at a venue every guest shares one public IP. A per-IP limit
+/// therefore bounds nothing globally.
+///
+/// `cores - 1` leaves a core for actually serving requests. Excess callers WAIT on the permit
+/// rather than burning CPU, so a flood degrades to latency instead of an outage.
+static BCRYPT_PERMITS: std::sync::LazyLock<tokio::sync::Semaphore> =
+    std::sync::LazyLock::new(|| {
+        let cores = std::thread::available_parallelism()
+            .map(|n| n.get())
+            .unwrap_or(2);
+        tokio::sync::Semaphore::new(cores.saturating_sub(1).max(1))
+    });
+
+async fn verify_password(candidate: String, hash: String) -> bool {
+    // `acquire()` only fails if the semaphore is closed, which never happens here.
+    let _permit = BCRYPT_PERMITS.acquire().await;
+    tokio::task::spawn_blocking(move || bcrypt::verify(&candidate, &hash).unwrap_or(false))
+        .await
+        .unwrap_or(false)
+}
+
+/// Hash a secret on the blocking pool. Same reasoning as [`verify_password`] — and this one
+/// runs on the busiest auth path there is, since every guest who joins gets a PIN hashed.
+pub async fn hash_password(secret: String, cost: u32) -> Result<String, AppError> {
+    // Same global ceiling as `verify_password` — `/join` hashes a PIN for every guest, and 100
+    // guests scanning the QR at once is the arrival burst this box has to survive.
+    let _permit = BCRYPT_PERMITS.acquire().await;
+    tokio::task::spawn_blocking(move || bcrypt::hash(&secret, cost))
+        .await
+        .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?
+        .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))
+}
+
 pub async fn recover(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<RecoverRequest>,
 ) -> Result<Json<RecoverResponse>, AppError> {
-    let display_name = body.display_name.trim();
+    // Validated BEFORE it is used as a rate-limiter key — see `validate_display_name`. The
+    // per-IP ceiling below is keyed only on the IP, so it is safe to run either side of this;
+    // the per-NAME bucket is not.
+    let display_name = validate_display_name(&body.display_name)?;
 
-    // Per-IP+name throttle BEFORE the per-user 3-strike counter. Without this
-    // an attacker who knows a display name (they're visible on the feed) can
-    // burn through 3 wrong PINs and lock the victim for 15 minutes — repeated
-    // every 15 minutes, indefinitely. 5 attempts per 15 minutes per (IP, name)
-    // softens that into a real cost.
-    let ip = client_ip(&headers, "unknown");
-    let rate_limits_on = config::get_bool(&state.pool, "rate_limits_enabled", true).await;
-    let recover_rate_on = config::get_bool(&state.pool, "recover_rate_enabled", true).await;
+    // Per-IP+name throttle BEFORE the per-user lockout counter. Without this an attacker who
+    // knows a display name (they're visible on the feed) can burn through the victim's wrong-PIN
+    // budget and lock them out, repeatedly. The ceiling here MUST stay below
+    // PIN_LOCK_THRESHOLD — see the constant for why that ordering is the whole control.
+    let ip = client_ip(&headers, &peer.ip().to_string());
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let recover_rate_on = config::get_bool(&state.config_cache, "recover_rate_enabled", true).await;
     if rate_limits_on && recover_rate_on {
+        // Coarse per-IP ceiling FIRST. The per-(ip, name) bucket below is the anti-guessing
+        // control, but the name is attacker-chosen, so cycling names mints a fresh bucket
+        // every time and leaves the per-IP cost unbounded. That matters more here than
+        // anywhere else: every call runs a cost-12 bcrypt verify, including an
+        // unconditional throwaway one for names that don't exist (see below), so an unknown
+        // name is the CHEAPEST way to make the server do ~200ms of hashing. Checked before
+        // the per-name bucket so a name generator can't walk past it.
+        let ip_ceiling =
+            config::get_usize(&state.config_cache, "recover_ip_rate_per_min", 30).await;
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("recover_ip:{ip}"),
+            ip_ceiling,
+            Duration::from_secs(60),
+        ) {
+            return Err(AppError::TooManyRequests(
+                "Zu viele Versuche. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
+
+        let name_ceiling = config::get_usize(
+            &state.config_cache,
+            "recover_name_rate_per_15min",
+            RECOVER_NAME_CEILING_DEFAULT,
+        )
+        .await
+        // CLAMPED, not merely defaulted — see RECOVER_NAME_CEILING_MAX. The config value is
+        // operator-settable and the invariant it has to respect is not expressible in
+        // `patch_config`'s numeric range, so it is enforced at the point of use.
+        .min(RECOVER_NAME_CEILING_MAX);
         let name_key = display_name.to_lowercase();
-        if !state.rate_limiter.check(
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
             format!("recover:{ip}:{name_key}"),
-            5,
+            name_ceiling,
             Duration::from_secs(15 * 60),
         ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Versuche. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }
@@ -165,32 +369,39 @@ pub async fn recover(
         .await?
         .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
 
-    let users =
-        User::find_by_event_and_name(&state.pool, event.id, display_name).await?;
+    let users = User::find_by_event_and_name(&state.pool, event.id, display_name).await?;
 
     if users.is_empty() {
-        return Err(AppError::NotFound(
-            "Kein Benutzer mit diesem Namen gefunden.".into(),
-        ));
+        // No user with this name. Run a throwaway bcrypt verify so this branch takes
+        // the same time as the user-exists path, and return the SAME error as a wrong
+        // PIN — so "no such name" and "wrong PIN" are indistinguishable by response or
+        // timing. Display names are already public on the feed, but this still closes
+        // the /recover enumeration + timing oracle.
+        let _ = verify_password(body.pin.clone(), dummy_pin_hash().to_string()).await;
+        return Err(AppError::Unauthorized("PIN ist falsch.".into()));
     }
 
     for user in &users {
-        // Check PIN lockout. The failed-attempt counter is deliberately NOT reset
-        // when the window expires — it drives the *escalating* backoff below, so a
-        // determined guesser faces an exponentially growing wait. A successful
-        // recovery (and a host PIN reset) is what clears it. The counter only ever
-        // grows on a *wrong* PIN, so a legitimate user is unaffected.
+        // Check PIN lockout. If the lockout has expired, also reset the failed-attempt
+        // counter so the user gets a fresh 3-strike window — otherwise the counter
+        // stays at 3+ and every subsequent wrong PIN immediately re-locks them, even
+        // after waiting out the cooldown. Without this reset, a once-locked account
+        // is effectively permanently fragile.
         if let Some(locked_until) = user.pin_locked_until {
             if Utc::now() < locked_until {
+                // The exact deadline is known, so surface it as Retry-After instead of
+                // making the client guess at the "15 Minuten" in the copy.
+                let retry_after_secs = (locked_until - Utc::now()).num_seconds().max(1) as u64;
                 return Err(AppError::TooManyRequests(
-                    "Zu viele Versuche. Bitte warte und versuche es später erneut.".into(),
-                    None,
+                    "Zu viele Versuche. Bitte warte 15 Minuten.".into(),
+                    Some(retry_after_secs),
                 ));
             }
+            // Lockout window expired — wipe the counter and the timestamp.
+            User::reset_pin_attempts(&state.pool, user.id).await?;
         }
 
-        let pin_matches =
-            password::verify(body.pin.clone(), user.recovery_pin_hash.clone()).await;
+        let pin_matches = verify_password(body.pin.clone(), user.recovery_pin_hash.clone()).await;
 
         if pin_matches {
             // Reset failed attempts on success
@@ -224,20 +435,14 @@ pub async fn recover(
             attempts,
             "recover: wrong PIN"
         );
-        if attempts >= 3 {
-            // Escalating backoff: 15min, 30, 60, … doubling per failure past the
-            // threshold, capped at 24h. Makes sustained guessing against the
-            // 6-digit space (1M combinations) astronomically slow.
-            let exp = (attempts as u32).saturating_sub(3).min(10);
-            let minutes = 15i64.saturating_mul(1i64 << exp).min(24 * 60);
-            let lockout = Utc::now() + chrono::Duration::minutes(minutes);
+        if attempts >= PIN_LOCK_THRESHOLD {
+            let lockout = Utc::now() + chrono::Duration::minutes(15);
             User::lock_pin(&state.pool, user.id, lockout).await?;
             tracing::warn!(
                 user_id = %user.id,
                 event_id = %event.id,
                 ip = %ip,
-                minutes,
-                "recover: account locked (escalating backoff)"
+                "recover: account locked for 15 minutes"
             );
         }
     }
@@ -253,10 +458,27 @@ pub struct AdminLoginRequest {
 #[derive(Serialize)]
 pub struct AdminLoginResponse {
     pub jwt: String,
+    /// The admin's user id + display name, so the client can populate a real identity
+    /// (own-post affordances, a name on the Account page) instead of a blank session.
+    pub user_id: Uuid,
+    pub display_name: String,
 }
 
+/// Requests per minute per IP that may reach `verify_password` at all.
+///
+/// Not a security control — the failure bucket below is. It bounds how deep a queue can form on
+/// `BCRYPT_PERMITS`, which is what actually caps the CPU cost.
+///
+/// Still far above anything a person typing a password produces, but note the honest limitation:
+/// unlike the failure bucket, this ceiling CAN refuse a correct password, and on venue NAT every
+/// guest shares the operator's IP. It is a smaller number than it first was for exactly that
+/// reason — the earlier 120 was chosen when this was the only bound on bcrypt, which made it both
+/// too weak to cap CPU and too coarse to be safe for the operator.
+const ADMIN_LOGIN_CPU_CEILING: usize = 30;
+
 pub async fn admin_login(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<AdminLoginRequest>,
 ) -> Result<Json<AdminLoginResponse>, AppError> {
@@ -266,49 +488,63 @@ pub async fn admin_login(
         ));
     }
 
-    // Throttle password attempts. The admin password is bcrypt-hashed (slow to
-    // verify) but with no IP-level limit a determined attacker can still mount
-    // a long-running guess campaign. 5 attempts / minute / IP is plenty for
-    // honest typos.
-    let ip = client_ip(&headers, "unknown");
+    // Throttling here is in two parts, and the ORDER is the whole point.
+    //
+    // A single tight IP-keyed bucket checked before the password was verified made this
+    // endpoint a denial-of-service against its own operator. Every guest at the venue shares
+    // one public IP behind NAT, `/admin/login` is a public linkable page, and the check ran
+    // BEFORE `verify_password` — so five requests a minute from any phone in the room kept the
+    // bucket permanently full and the admin, on that same IP, could never spend a slot.
+    // Successful logins consumed budget too, so a typo plus a retry on two devices did it by
+    // accident. And the escape hatch was circular: `admin_login_rate_enabled` can only be
+    // flipped through `PATCH /admin/config`, which needs the session being blocked.
+    let ip = client_ip(&headers, &peer.ip().to_string());
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let admin_rate_on =
+        config::get_bool(&state.config_cache, "admin_login_rate_enabled", true).await;
 
-    // Hard, non-disableable floor: admin_login is the one credential endpoint
-    // whose brute-force protection must survive the DB rate-limit master toggle
-    // being turned off. 30 attempts / 5 min / IP is generous for typos but caps
-    // sustained guessing regardless of config.
-    if !state.rate_limiter.check(
-        format!("admin_login_floor:{ip}"),
-        30,
-        Duration::from_secs(300),
-    ) {
-        return Err(AppError::TooManyRequests(
-            "Zu viele Anmeldeversuche. Bitte warte kurz und versuche es erneut.".into(),
-            None,
-        ));
-    }
-
-    let rate_limits_on = config::get_bool(&state.pool, "rate_limits_enabled", true).await;
-    let admin_rate_on = config::get_bool(&state.pool, "admin_login_rate_enabled", true).await;
-    if rate_limits_on && admin_rate_on
-        && !state.rate_limiter.check(
-            format!("admin_login:{ip}"),
-            5,
+    // Part 1: a deliberately GENEROUS ceiling whose only job is to bound bcrypt CPU. Cost-12
+    // verification is ~250 ms of a core, so an unbounded endpoint is a CPU exhaustion vector
+    // regardless of whether anyone guesses right. No human typing a password reaches this.
+    if rate_limits_on
+        && admin_rate_on
+        && let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("admin_login_cpu:{ip}"),
+            ADMIN_LOGIN_CPU_CEILING,
             Duration::from_secs(60),
         )
     {
         return Err(AppError::TooManyRequests(
             "Zu viele Anmeldeversuche. Bitte warte kurz und versuche es erneut.".into(),
-            None,
+            Some(retry_after_secs),
         ));
     }
 
-    let valid = password::verify(
+    let valid = verify_password(
         body.password.clone(),
         state.config.admin_password_hash.clone(),
     )
     .await;
 
     if !valid {
+        // Part 2: the tight bucket, charged ONLY on a wrong password. A correct password is
+        // never rate-limited, so no amount of guessing by anyone else can lock the operator
+        // out — which also dissolves the circular escape hatch above. Brute force is still
+        // bounded: every wrong guess costs a slot, and slots are per-IP.
+        if rate_limits_on
+            && admin_rate_on
+            && let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+                format!("admin_login_fail:{ip}"),
+                5,
+                Duration::from_secs(60),
+            )
+        {
+            tracing::warn!(ip = %ip, "admin_login: wrong password, failure bucket exhausted");
+            return Err(AppError::TooManyRequests(
+                "Zu viele Anmeldeversuche. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
         tracing::warn!(ip = %ip, "admin_login: wrong password");
         return Err(AppError::Unauthorized("Falsches Passwort.".into()));
     }
@@ -320,27 +556,16 @@ pub async fn admin_login(
     )
     .await?;
 
-    // Find or create the admin user for this event
-    let admin_name = "Admin";
-    let users = User::find_by_event_and_name(&state.pool, event.id, admin_name).await?;
-    let admin_user = if let Some(u) = users.into_iter().find(|u| u.role == UserRole::Admin) {
-        u
-    } else {
-        // Admin authenticates via password, but the schema still requires a PIN
-        // hash. Generate a random unguessable PIN so the recovery path remains
-        // unusable as an escalation route even if the role flag ever got cleared.
-        let dummy_pin: String = (0..32)
-            .map(|_| rand::rng().random_range(b'a'..=b'z') as char)
-            .collect();
-        let dummy_hash = password::hash(dummy_pin, 4).await?;
-        let user = User::create(&state.pool, event.id, admin_name, &dummy_hash).await?;
-        sqlx::query("UPDATE \"user\" SET role = 'admin' WHERE id = $1")
-            .bind(user.id)
-            .execute(&state.pool)
-            .await?;
-        User::find_by_id(&state.pool, user.id)
-            .await?
-            .ok_or_else(|| AppError::Internal(anyhow::anyhow!("admin user creation failed")))?
+    // Find or create the admin user for this event — BY ROLE, never by name.
+    //
+    // The name lookup this replaces is what made admin login brickable. Migration 007 makes
+    // display_name unique per event case-insensitively and `join` had no reserved-name guard,
+    // so a guest joining as "admin" before the operator's first login made the lookup miss on
+    // role, the fallback `create("Admin")` violate that index, and `?` return a permanent 500 —
+    // taking out moderation, config and gallery release with no in-app recovery.
+    let admin_user = match User::find_admin_for_event(&state.pool, event.id).await? {
+        Some(u) => u,
+        None => create_admin_user(&state, event.id).await?,
     };
 
     tracing::info!(user_id = %admin_user.id, event_id = %event.id, ip = %ip, "admin_login: success");
@@ -358,13 +583,236 @@ pub async fn admin_login(
     let expires_at = Utc::now() + chrono::Duration::days(1);
     Session::create(&state.pool, admin_user.id, &token_hash, expires_at).await?;
 
-    Ok(Json(AdminLoginResponse { jwt: token }))
+    Ok(Json(AdminLoginResponse {
+        jwt: token,
+        user_id: admin_user.id,
+        display_name: admin_user.display_name,
+    }))
 }
 
-pub async fn logout(
-    State(state): State<AppState>,
-    auth: AuthUser,
-) -> Result<StatusCode, AppError> {
+/// Create this event's admin row on first successful admin login.
+///
+/// Prefers the name "Admin". If a legacy database has a guest squatting on it — the state
+/// migration 023 renames away, but a row could also predate that or be created between
+/// migrations — falls back to a suffixed name rather than failing the login.
+///
+/// PROMOTING THE SQUATTING ROW WOULD BE A SERIOUS MISTAKE, and is the obvious-looking fix, so
+/// it is spelled out: that row carries a `recovery_pin_hash` the guest knows. Setting
+/// `role = 'admin'` on it would hand them the admin dashboard through `/recover`, permanently,
+/// via a path that needs no password. A separate row under an uglier name is worse UX and much
+/// better security — and since the lookup is now by role, the fallback name never has to be
+/// guessed again on a later login.
+async fn create_admin_user(state: &AppState, event_id: Uuid) -> Result<User, AppError> {
+    // Admin authenticates via password, but the schema still requires a PIN hash. Generate a
+    // random unguessable one so the recovery path stays unusable as an escalation route even if
+    // the role flag were ever cleared.
+    let dummy_pin: String = (0..32)
+        .map(|_| rand::rng().random_range(b'a'..=b'z') as char)
+        .collect();
+    let dummy_hash = hash_password(dummy_pin, 4).await?;
+
+    match User::create_with_role(&state.pool, event_id, "Admin", &dummy_hash, UserRole::Admin).await
+    {
+        Ok(u) => Ok(u),
+        Err(sqlx::Error::Database(db)) if db.is_unique_violation() => {
+            let fallback = format!("Admin-{}", &Uuid::new_v4().to_string()[..8]);
+            tracing::warn!(
+                %event_id, %fallback,
+                "the name \"Admin\" is held by a non-admin user; creating the admin under a \
+                 fallback name. Rename that guest to free it — do NOT promote their row, they \
+                 know its recovery PIN."
+            );
+            Ok(User::create_with_role(
+                &state.pool,
+                event_id,
+                &fallback,
+                &dummy_hash,
+                UserRole::Admin,
+            )
+            .await?)
+        }
+        Err(e) => Err(e.into()),
+    }
+}
+
+pub async fn logout(State(state): State<AppState>, auth: AuthUser) -> Result<StatusCode, AppError> {
     Session::delete_by_token_hash(&state.pool, &auth.token_hash).await?;
     Ok(StatusCode::NO_CONTENT)
 }
+
+/// "Sign out everywhere" — revoke every session for the caller, not just the current one.
+/// A single leaked/kept-alive device (a shared phone, a laptop recovered via PIN) can then
+/// be cut from any of the user's devices.
+pub async fn logout_all(
+    State(state): State<AppState>,
+    auth: AuthUser,
+) -> Result<StatusCode, AppError> {
+    Session::delete_all_for_user(&state.pool, auth.user_id).await?;
+    Ok(StatusCode::NO_CONTENT)
+}
+
+#[derive(Deserialize)]
+pub struct PinResetRequestBody {
+    pub display_name: String,
+}
+
+/// A guest who forgot their PIN asks a host to reset it in-app. Unauthenticated (they
+/// can't log in without the PIN) and rate-limited. Always returns 204 regardless of
+/// whether the name exists, so it can't enumerate display names beyond what the public
+/// feed already exposes.
+pub async fn request_pin_reset(
+    State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
+    headers: HeaderMap,
+    Json(body): Json<PinResetRequestBody>,
+) -> Result<StatusCode, AppError> {
+    let ip = client_ip(&headers, &peer.ip().to_string());
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+
+    // Coarse per-IP ceiling FIRST, keyed only on the IP so its key is bounded by construction.
+    // /join got one of these in migration 017 and /recover in 019; this third unauthenticated
+    // endpoint was simply missed — migration 019's own comment describes exactly this attack.
+    // Without it, the per-name bucket below is no ceiling at all: the name is attacker-chosen,
+    // so cycling names mints a fresh bucket every request.
+    if rate_limits_on {
+        let ip_ceiling =
+            config::get_usize(&state.config_cache, "pin_reset_ip_rate_per_min", 30).await;
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("pin_reset_ip:{ip}"),
+            ip_ceiling,
+            Duration::from_secs(60),
+        ) {
+            return Err(AppError::TooManyRequests(
+                "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
+    }
+
+    // Validated BEFORE the per-name key is built, so an unbounded name can never be retained in
+    // the limiter map. NOTE the 204: this endpoint's contract is that it answers identically
+    // whether or not the name exists, so it cannot enumerate guests. A 400 here would be a new
+    // signal — it would distinguish a malformed name from a well-formed unknown one. Silence is
+    // the correct response, and matches what an empty name already did.
+    let Ok(display_name) = validate_display_name(&body.display_name) else {
+        return Ok(StatusCode::NO_CONTENT);
+    };
+
+    if rate_limits_on {
+        let name_key = display_name.to_lowercase();
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("pin_reset_req:{ip}:{name_key}"),
+            3,
+            Duration::from_secs(15 * 60),
+        ) {
+            return Err(AppError::TooManyRequests(
+                "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
+    }
+
+    // Single statement so the existing-name and unknown-name paths do IDENTICAL work
+    // (same event+user index scans, an INSERT that matches 0 rows for an unknown name) —
+    // no timing oracle despite the always-204 contract. Admins recover via password, so
+    // they're excluded from the join and never get a reset request queued.
+    let _ = sqlx::query(
+        "INSERT INTO pin_reset_request (event_id, user_id)
+         SELECT e.id, u.id
+         FROM event e
+         JOIN \"user\" u
+           ON u.event_id = e.id
+          AND lower(u.display_name) = lower($2)
+          AND u.role <> 'admin'
+         WHERE e.slug = $1
+         ON CONFLICT (user_id) DO NOTHING",
+    )
+    .bind(&state.config.event_slug)
+    .bind(display_name)
+    .execute(&state.pool)
+    .await;
+
+    // Broadcast unconditionally (carries no per-name info) so an online host's request
+    // badge updates without revealing whether the name existed.
+    let _ = state
+        .sse_tx
+        .send(crate::state::SseEvent::new("pin-reset-requested", "{}"));
+
+    Ok(StatusCode::NO_CONTENT)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Control characters are rejected at the door. Newlines in particular: several 4xx messages
+    /// interpolate the display name and those are logged, so a name carrying a newline plus a
+    /// plausible prefix would let two unauthenticated requests forge lines in the event's only
+    /// forensic record. `error.rs` escapes on output too; this keeps it out of the database and
+    /// the feed byline in the first place.
+    #[test]
+    fn a_display_name_may_not_carry_control_characters() {
+        for bad in ["Anna\nERROR forged", "Anna\rX", "Anna\u{0}X", "A\u{7}B"] {
+            assert!(validate_display_name(bad).is_err(), "{bad:?} must be rejected");
+        }
+        // Real guests have accents, emoji and non-Latin names — never reject those.
+        for good in ["Anna", "Zo\u{eb}", "Jos\u{e9}", "\u{5c71}\u{7530}", "Anna \u{1f389}"] {
+            assert!(validate_display_name(good).is_ok(), "{good:?} must be allowed");
+        }
+    }
+
+    /// THE defect, stated as arithmetic: the account-lock threshold sat BELOW the per-(IP, name)
+    /// attempt ceiling, so a single IP could exhaust it and lock any guest whose display name is
+    /// visible on the feed — every 15 minutes, indefinitely. The tier meant to protect a guest
+    /// was the cheapest way to attack them.
+    ///
+    /// The fix is the ORDERING, not either number on its own, so that is what this pins.
+    #[test]
+    fn one_ip_cannot_reach_the_account_lock() {
+        assert!(
+            PIN_LOCK_THRESHOLD as usize >= RECOVER_NAME_CEILING_MAX * 3,
+            "locking a victim must require at least three distinct sources; \
+             threshold {PIN_LOCK_THRESHOLD} vs the ENFORCED per-IP ceiling \
+             {RECOVER_NAME_CEILING_MAX} (the default is {RECOVER_NAME_CEILING_DEFAULT})"
+        );
+    }
+
+    /// Raising the threshold must not quietly weaken brute-force resistance. 4-digit PINs, and
+    /// the lockout window is 15 minutes, so an attacker gets PIN_LOCK_THRESHOLD tries per window.
+    #[test]
+    fn the_raised_threshold_still_makes_guessing_a_four_digit_pin_impractical() {
+        let attempts_per_hour = PIN_LOCK_THRESHOLD as u64 * 4; // four 15-minute windows
+        let hours_for_full_keyspace = 10_000 / attempts_per_hour;
+        assert!(
+            hours_for_full_keyspace >= 168,
+            "exhausting 10k PINs would take {hours_for_full_keyspace}h — under a week is too fast"
+        );
+    }
+
+    #[test]
+    fn reserved_names_are_matched_case_insensitively_and_trimmed() {
+        for name in ["admin", "Admin", "ADMIN", "  Host  ", "EventSnap"] {
+            assert!(is_reserved_display_name(name), "{name} must be reserved");
+        }
+    }
+
+    /// A substring match here would reject perfectly ordinary names, which is a worse outcome
+    /// than the impersonation the list guards against.
+    #[test]
+    fn names_that_merely_contain_a_reserved_word_are_allowed() {
+        for name in ["Administrata", "Hostess", "Adminah", "Ghost", "hosting"] {
+            assert!(!is_reserved_display_name(name), "{name} must be allowed");
+        }
+    }
+
+    #[test]
+    fn display_names_are_bounded_before_they_can_become_a_rate_limit_key() {
+        assert!(validate_display_name("  Lena  ").is_ok());
+        assert_eq!(validate_display_name("  Lena  ").unwrap(), "Lena");
+        // The case that made the limiter itself the exhaustion primitive.
+        assert!(validate_display_name(&"a".repeat(51)).is_err());
+        assert!(validate_display_name(&"a".repeat(2_000_000)).is_err());
+        assert!(validate_display_name("   ").is_err());
+        assert!(validate_display_name("bad\0name").is_err());
+    }
+}

backend/src/auth/jwt.rs

@@ -46,10 +46,20 @@ pub fn create_token(
 }
 
 pub fn verify_token(token: &str, secret: &str) -> Result<Claims, jsonwebtoken::errors::Error> {
+    // We deliberately do NOT enforce the JWT's own `exp`. The authoritative session
+    // lifetime lives in the `session` row (`expires_at > NOW()`), which SLIDES forward on
+    // every authenticated request (see `Session::touch_and_renew`). Enforcing the JWT's
+    // fixed +Nd `exp` here would hard-log-out an actively-used client on day N+1 even
+    // though its session was renewed — the "30-day cliff" from the review. With server-
+    // side sliding sessions, the token is a signature-checked bearer credential and its
+    // lifetime is revocable (logout / expiry / ban all delete the row), which is strictly
+    // stronger than a stateless non-revocable exp.
+    let mut validation = Validation::default();
+    validation.validate_exp = false;
     let data = jsonwebtoken::decode::<Claims>(
         token,
         &DecodingKey::from_secret(secret.as_bytes()),
-        &Validation::default(),
+        &validation,
     )?;
     Ok(data.claims)
 }

backend/src/auth/middleware.rs

@@ -13,6 +13,10 @@ pub struct AuthUser {
     pub user_id: Uuid,
     pub event_id: Uuid,
     pub role: UserRole,
+    /// Live ban flag. Banned users keep *read* access (per USER_JOURNEYS §10), so
+    /// the base extractor does NOT reject them — write handlers and the
+    /// Require{Host,Admin} extractors enforce the ban instead.
+    pub is_banned: bool,
     pub token_hash: String,
 }
 
@@ -33,49 +37,51 @@ impl FromRequestParts<AppState> for AuthUser {
             .strip_prefix("Bearer ")
             .ok_or_else(|| AppError::Unauthorized("Ungültiges Token-Format.".into()))?;
 
-        let claims = jwt::verify_token(token, &state.config.jwt_secret)
+        // Verify the JWT's signature. Expiry is deliberately NOT enforced here (see
+        // `jwt::verify_token`) — the authoritative, sliding session lifetime lives in the
+        // `session` row read below. We also don't trust the token's role/ban claims; the
+        // live user row is authoritative, so the decoded claims aren't needed beyond this.
+        jwt::verify_token(token, &state.config.jwt_secret)
             .map_err(|_| AppError::Unauthorized("Token ungültig oder abgelaufen.".into()))?;
 
         let token_hash = jwt::hash_token(token);
 
-        // Reconcile the session against the live `user` row. We do NOT trust the
-        // JWT claims for role/ban/event — a token can outlive a ban or demotion
-        // (default lifetime 30 days). The single JOIN query is the same number
-        // of round-trips as the old existence check.
-        let ctx = Session::find_auth_context(&state.pool, &token_hash)
+        // Single round-trip: resolve the session token to its *live* user row. A
+        // role/ban stored in the token would survive a demote/ban for the full session
+        // lifetime (up to 30d), so we always re-read the user (a demoted host loses host
+        // powers immediately). We do NOT reject banned users here — they retain read
+        // access by design; writes and host/admin actions enforce the ban downstream.
+        let user = Session::find_user_by_token_hash(&state.pool, &token_hash)
             .await
             .map_err(|e| AppError::Internal(e.into()))?
-            .ok_or_else(|| AppError::Unauthorized("Sitzung nicht gefunden oder abgelaufen.".into()))?;
+            .ok_or_else(|| {
+                AppError::Unauthorized("Sitzung nicht gefunden oder abgelaufen.".into())
+            })?;
 
-        // Ban takes effect immediately on the next request, regardless of the
-        // token's remaining lifetime.
-        if ctx.is_banned {
-            return Err(AppError::Forbidden("Du bist gesperrt.".into()));
-        }
-
-        // Defend against a JWT that was issued for a different user/event than
-        // the session's DB row points at (e.g. a swapped or replayed token).
-        if claims.sub != ctx.user_id || claims.event_id != ctx.event_id {
-            return Err(AppError::Unauthorized("Token passt nicht zur Sitzung.".into()));
-        }
-
-        // Update last_seen_at in the background (fire-and-forget). Failures are
-        // non-fatal but worth surfacing — silent swallowing hides DB connection
-        // pressure that would otherwise be the first symptom of a real problem.
+        // Touch last_seen_at AND slide the session's expiry forward (fire-and-forget), so
+        // an active client's session renews instead of hitting the fixed 30-day cliff.
+        // Admin sessions keep their tighter 1-day window (they renew on activity but still
+        // lapse a day after the admin goes idle). Failures are non-fatal but worth
+        // surfacing — silent swallowing hides DB connection pressure that would otherwise
+        // be the first symptom of a real problem.
         let pool = state.pool.clone();
-        let session_id = ctx.session_id;
+        let touch_hash = token_hash.clone();
+        let expiry_days = if user.role == UserRole::Admin {
+            1
+        } else {
+            state.config.session_expiry_days
+        };
         tokio::spawn(async move {
-            if let Err(e) = Session::touch(&pool, session_id).await {
-                tracing::warn!(error = ?e, session_id = %session_id, "session touch failed");
+            if let Err(e) = Session::touch_and_renew(&pool, &touch_hash, expiry_days).await {
+                tracing::warn!(error = ?e, "session touch/renew failed");
             }
         });
 
         Ok(Self {
-            user_id: ctx.user_id,
-            event_id: ctx.event_id,
-            // Live role from the DB, not the claim — demotion/promotion takes
-            // effect on the next request.
-            role: ctx.role,
+            user_id: user.id,
+            event_id: user.event_id,
+            role: user.role,
+            is_banned: user.is_banned,
             token_hash,
         })
     }
@@ -92,6 +98,9 @@ impl FromRequestParts<AppState> for RequireHost {
         state: &AppState,
     ) -> Result<Self, Self::Rejection> {
         let auth = AuthUser::from_request_parts(parts, state).await?;
+        if auth.is_banned {
+            return Err(AppError::Forbidden("Du bist gesperrt.".into()));
+        }
         match auth.role {
             UserRole::Host | UserRole::Admin => Ok(Self(auth)),
             _ => Err(AppError::Forbidden("Nur für Hosts und Admins.".into())),
@@ -110,6 +119,9 @@ impl FromRequestParts<AppState> for RequireAdmin {
         state: &AppState,
     ) -> Result<Self, Self::Rejection> {
         let auth = AuthUser::from_request_parts(parts, state).await?;
+        if auth.is_banned {
+            return Err(AppError::Forbidden("Du bist gesperrt.".into()));
+        }
         match auth.role {
             UserRole::Admin => Ok(Self(auth)),
             _ => Err(AppError::Forbidden("Nur für Admins.".into())),

backend/src/config.rs

@@ -1,11 +1,120 @@
 use std::path::PathBuf;
 
-use anyhow::{anyhow, Context, Result};
+use anyhow::{Context, Result, anyhow};
 
 /// Well-known dev JWT secret shipped in `.env.example`. If APP_ENV=production
 /// we refuse to start with this value; otherwise we warn loudly.
 const DEV_JWT_SECRET_SENTINEL: &str = "dev_secret_do_not_use_in_production_32byteslong_aaaa";
 
+/// A secret is "placeholder-ish" if it's the shipped dev sentinel or still carries
+/// the tell-tale scaffolding substrings from `.env.example`. Length alone is not
+/// enough — the shipped `change_me_...` placeholder is >32 chars.
+fn looks_placeholder(s: &str) -> bool {
+    let lower = s.to_ascii_lowercase();
+    s == DEV_JWT_SECRET_SENTINEL
+        || lower.contains("change_me")
+        || lower.contains("dev_secret")
+        || lower.contains("placeholder")
+}
+
+/// A bcrypt hash is exactly 60 characters and opens with `$2<variant>$<cost>$`.
+///
+/// Checking the SHAPE, not just placeholder-ness, is what catches a hash silently mangled in
+/// transit. The `$` segments are variable-expansion bait for both shell quoting and Docker
+/// Compose's `env_file` parsing, and a mangled hash is not a placeholder — so without this it
+/// passes every other guard here, the app boots green, `/health` returns `ok`, and every admin
+/// login 401s.
+///
+/// That failure is unrecoverable mid-event, which is why it is worth a hard fail at boot: the
+/// Admin row is created BY a successful admin login (`auth/handlers.rs`), and only an Admin or
+/// Host can promote a Host. No admin login therefore means no host at all — the event cannot be
+/// closed, the gallery cannot be released, and nothing can be moderated.
+fn looks_bcrypt(s: &str) -> bool {
+    let b = s.as_bytes();
+    s.len() == 60
+        && b[0] == b'$'
+        && b[1] == b'2'
+        && matches!(b[2], b'a' | b'b' | b'x' | b'y')
+        && b[3] == b'$'
+        && b[4].is_ascii_digit()
+        && b[5].is_ascii_digit()
+        && b[6] == b'$'
+}
+
+/// Enforce secret hygiene. In production every guard is hard-fail: a booting app
+/// with a publicly-known signing key is worse than one that refuses to start.
+/// Outside production the dev sentinel is tolerated (warned) so local dev is frictionless.
+///
+/// EVERY failure is collected and reported together. Returning on the first one made fixing two
+/// secrets cost two boot cycles — the operator rotates JWT_SECRET, restarts, and only then learns
+/// about ADMIN_PASSWORD_HASH. Restarting this stack is not free (Caddy waits on the unhealthy app),
+/// and each avoidable cycle is another chance to reach for `down -v`.
+fn validate_secrets(
+    is_prod: bool,
+    jwt_secret: &str,
+    admin_password_hash: &str,
+    database_url: &str,
+) -> Result<()> {
+    if is_prod {
+        let mut problems: Vec<&str> = Vec::new();
+        if looks_placeholder(jwt_secret) {
+            problems.push(
+                "JWT_SECRET is still the .env.example placeholder — rotate it \
+                 (openssl rand -hex 64).",
+            );
+        } else if jwt_secret.len() < 32 {
+            problems.push("JWT_SECRET must be at least 32 characters.");
+        }
+        if admin_password_hash.is_empty() || looks_placeholder(admin_password_hash) {
+            problems.push(
+                "ADMIN_PASSWORD_HASH is unset or still the .env.example placeholder — generate one \
+                 (docker run --rm caddy:2-alpine caddy hash-password --plaintext '<password>').",
+            );
+        } else if !looks_bcrypt(admin_password_hash) {
+            problems.push(
+                "ADMIN_PASSWORD_HASH is not a well-formed bcrypt hash: expected exactly 60 \
+                 characters starting `$2b$12$…`. First look at the value that actually reached \
+                 the app — `docker compose exec app printenv ADMIN_PASSWORD_HASH` — and compare \
+                 it to .env character for character. In .env, SINGLE-QUOTE the hash \
+                 ('$2b$12$…'): Compose uses single-quoted env_file values literally, so the `$` \
+                 segments survive. Double them to `$$` ONLY when setting the value under \
+                 `environment:` in docker-compose.yml — doing that in .env corrupts a hash that \
+                 would otherwise have worked. Regenerate with: \
+                 docker run --rm caddy:2-alpine caddy hash-password --plaintext '<password>'",
+            );
+        }
+        // The DATABASE_URL carries the Postgres password, so a placeholder here means the stack is
+        // running on `CHANGE_ME_use_a_strong_password` — a credential published in the repo. The
+        // app used to boot green on it, because this guard only ever covered the two secrets it
+        // was written for and nothing else looked at POSTGRES_PASSWORD at all.
+        //
+        // Read POSTGRES_PASSWORD's docs before changing this: it is applied ONLY at initdb, so the
+        // remedy is not "edit .env and restart" — see the 28P01 diagnostic in db.rs.
+        if looks_placeholder(database_url) {
+            problems.push(
+                "DATABASE_URL still carries the .env.example placeholder password — set a strong \
+                 one (openssl rand -hex 24) in BOTH DATABASE_URL and POSTGRES_PASSWORD.",
+            );
+        }
+        if !problems.is_empty() {
+            return Err(anyhow!(
+                "Refusing to start in production — {} secret(s) still unset or placeholder:\n  - {}\n\
+                 ALL secrets must be set BEFORE the first `docker compose up -d`: Postgres bakes \
+                 POSTGRES_PASSWORD into its data directory on first boot and ignores later changes.",
+                problems.len(),
+                problems.join("\n  - ")
+            ));
+        }
+    } else if jwt_secret == DEV_JWT_SECRET_SENTINEL {
+        tracing::warn!(
+            "JWT_SECRET is the dev sentinel — fine for local development, NEVER ship this."
+        );
+    } else if jwt_secret.len() < 32 {
+        return Err(anyhow!("JWT_SECRET must be at least 32 characters."));
+    }
+    Ok(())
+}
+
 #[derive(Clone, Debug)]
 pub struct AppConfig {
     pub database_url: String,
@@ -15,63 +124,276 @@ pub struct AppConfig {
     pub event_name: String,
     pub event_slug: String,
     pub media_path: PathBuf,
+    /// Where export archives are written. MUST be outside `media_path` — that
+    /// directory is served by a public `ServeDir`, so a predictable archive name
+    /// under it would leak the whole gallery to anonymous visitors.
+    pub export_path: PathBuf,
     pub app_port: u16,
+    /// Number of concurrent media compression workers (read once at boot).
+    pub compression_concurrency: usize,
+    /// Master switch for the comment feature (env `COMMENTS_ENABLED`, default true).
+    /// When false the backend rejects new comments and the frontend hides the whole
+    /// comment UI. Existing comments stay in the DB (hidden), so flipping it back
+    /// restores them. Boot-time immutable, like `compression_concurrency`.
+    pub comments_enabled: bool,
+    /// Default colour theme, used as the fallback when the DB config keys are unset.
+    /// Runtime overrides live in the `config` table (admin UI); these env vars only
+    /// seed the initial default. `preset` is an id the frontend knows (e.g.
+    /// "champagne-gold", "rose", … or "custom"); the two seeds are `#rrggbb` brand +
+    /// accent colours the whole palette is derived from.
+    pub default_theme_preset: String,
+    pub default_theme_primary: String,
+    pub default_theme_accent: String,
 }
 
+/// The shipped default brand/accent seed (champagne gold — matches the hand-tuned
+/// ramp in tailwind-theme.css). Kept here so an unset env still yields the current look.
+const DEFAULT_THEME_SEED: &str = "#8a6a2b";
+
 impl AppConfig {
     pub fn from_env() -> Result<Self> {
-        let app_env =
-            std::env::var("APP_ENV").unwrap_or_else(|_| "development".to_string());
+        let app_env = std::env::var("APP_ENV").unwrap_or_else(|_| "development".to_string());
         let is_prod = app_env.eq_ignore_ascii_case("production");
 
         let jwt_secret = std::env::var("JWT_SECRET").context("JWT_SECRET must be set")?;
-        // A weak/placeholder signing key lets anyone forge any token (including
-        // admin). Detect the known dev sentinel, the `.env.example` placeholder,
-        // and anything that smells like an unreplaced template value.
-        let lower = jwt_secret.to_ascii_lowercase();
-        let looks_placeholder = jwt_secret == DEV_JWT_SECRET_SENTINEL
-            || lower.contains("change")
-            || lower.contains("example")
-            || lower.contains("placeholder")
-            || lower.contains("replace");
+        let admin_password_hash = std::env::var("ADMIN_PASSWORD_HASH").unwrap_or_default();
+        let database_url = std::env::var("DATABASE_URL").context("DATABASE_URL must be set")?;
 
-        if is_prod {
-            // Production must use a real, strong secret — no placeholders, ≥64
-            // chars (an `openssl rand -hex 64` is 128 hex chars).
-            if looks_placeholder || jwt_secret.len() < 64 {
-                return Err(anyhow!(
-                    "Refusing to start in production: JWT_SECRET is a placeholder or too short. \
-                     Generate a real one (openssl rand -hex 64) and set it in the prod environment."
-                ));
-            }
-        } else if looks_placeholder || jwt_secret.len() < 32 {
-            tracing::warn!(
-                "JWT_SECRET looks like a dev/placeholder value — fine for local development, \
-                 NEVER ship this to production."
-            );
-        }
+        validate_secrets(is_prod, &jwt_secret, &admin_password_hash, &database_url)?;
 
         Ok(Self {
-            database_url: std::env::var("DATABASE_URL")
-                .context("DATABASE_URL must be set")?,
+            database_url,
             jwt_secret,
             session_expiry_days: std::env::var("SESSION_EXPIRY_DAYS")
                 .unwrap_or_else(|_| "30".to_string())
                 .parse()
                 .context("SESSION_EXPIRY_DAYS must be a number")?,
-            admin_password_hash: std::env::var("ADMIN_PASSWORD_HASH")
-                .unwrap_or_default(),
-            event_name: std::env::var("EVENT_NAME")
-                .unwrap_or_else(|_| "EventSnap".to_string()),
-            event_slug: std::env::var("EVENT_SLUG")
-                .context("EVENT_SLUG must be set")?,
+            admin_password_hash,
+            event_name: std::env::var("EVENT_NAME").unwrap_or_else(|_| "EventSnap".to_string()),
+            event_slug: std::env::var("EVENT_SLUG").context("EVENT_SLUG must be set")?,
             media_path: PathBuf::from(
                 std::env::var("MEDIA_PATH").unwrap_or_else(|_| "/media".to_string()),
             ),
+            export_path: PathBuf::from(
+                std::env::var("EXPORT_PATH").unwrap_or_else(|_| "/exports".to_string()),
+            ),
             app_port: std::env::var("APP_PORT")
                 .unwrap_or_else(|_| "3000".to_string())
                 .parse()
                 .context("APP_PORT must be a number")?,
+            compression_concurrency: std::env::var("COMPRESSION_WORKER_CONCURRENCY")
+                .ok()
+                .and_then(|v| v.parse().ok())
+                .filter(|&n| n >= 1)
+                .unwrap_or(2),
+            comments_enabled: std::env::var("COMMENTS_ENABLED")
+                .map(|v| {
+                    !matches!(
+                        v.trim().to_ascii_lowercase().as_str(),
+                        "false" | "0" | "no" | "off"
+                    )
+                })
+                .unwrap_or(true),
+            default_theme_preset: std::env::var("THEME_PRESET")
+                .unwrap_or_else(|_| "champagne-gold".to_string()),
+            default_theme_primary: std::env::var("THEME_PRIMARY")
+                .unwrap_or_else(|_| DEFAULT_THEME_SEED.to_string()),
+            default_theme_accent: std::env::var("THEME_ACCENT")
+                .unwrap_or_else(|_| DEFAULT_THEME_SEED.to_string()),
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const REAL_SECRET: &str = "a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2";
+    // A structurally valid bcrypt hash: exactly 60 chars, `$2y$12$` + 53 of salt/digest.
+    // The shape matters — `looks_bcrypt` enforces it, so a fixture of the wrong length
+    // would assert the opposite of what these tests claim.
+    const REAL_HASH: &str = "$2y$12$abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXY01";
+    const REAL_DB_URL: &str = "postgres://eventsnap:7f3a9c1e5b2d8a4f@db:5432/eventsnap";
+
+    #[test]
+    fn prod_rejects_shipped_placeholder_secret() {
+        // The exact string shipped in `.env` — >32 chars, so it must be caught by
+        // the substring guard, not the length check.
+        let err = validate_secrets(
+            true,
+            "change_me_to_a_random_64_byte_hex_string",
+            REAL_HASH,
+            REAL_DB_URL,
+        );
+        assert!(
+            err.is_err(),
+            "placeholder JWT_SECRET must be rejected in prod"
+        );
+    }
+
+    #[test]
+    fn prod_rejects_dev_sentinel_and_short_secret() {
+        assert!(validate_secrets(true, DEV_JWT_SECRET_SENTINEL, REAL_HASH, REAL_DB_URL).is_err());
+        assert!(validate_secrets(true, "tooshort", REAL_HASH, REAL_DB_URL).is_err());
+    }
+
+    /// The failure this guards is silent and unrecoverable mid-event: a hash whose `$`
+    /// segments were eaten by shell or Compose interpolation is NOT a placeholder, so every
+    /// other guard passes, the app boots green and `/health` reports ok — and then every
+    /// admin login 401s, which (because the Admin row is created by a successful login, and
+    /// only an Admin/Host can promote a Host) means no host exists for the whole event.
+    #[test]
+    fn prod_rejects_mangled_admin_hash() {
+        // What `$2y$12$…` degrades to once `$2y`/`$12` are read as unset variables.
+        assert!(validate_secrets(true, REAL_SECRET, "abcdefghijklmnop", REAL_DB_URL).is_err());
+        // Right prefix, truncated body — still not a usable hash.
+        assert!(validate_secrets(true, REAL_SECRET, "$2y$12$tooshort", REAL_DB_URL).is_err());
+        // Correct length but no bcrypt prefix at all.
+        assert!(validate_secrets(true, REAL_SECRET, &"x".repeat(60), REAL_DB_URL).is_err());
+        // All three shipped bcrypt variants stay acceptable.
+        let body = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXY01";
+        for variant in ["2a", "2b", "2y"] {
+            let hash = format!("${variant}$12${body}");
+            assert_eq!(hash.len(), 60);
+            assert!(
+                validate_secrets(true, REAL_SECRET, &hash, REAL_DB_URL).is_ok(),
+                "bcrypt variant ${variant}$ must be accepted"
+            );
+        }
+    }
+
+    #[test]
+    fn prod_rejects_missing_or_placeholder_admin_hash() {
+        assert!(validate_secrets(true, REAL_SECRET, "", REAL_DB_URL).is_err());
+        assert!(
+            validate_secrets(
+                true,
+                REAL_SECRET,
+                "$2y$12$placeholder_replace_me",
+                REAL_DB_URL
+            )
+            .is_err()
+        );
+    }
+
+    /// The stack used to come up GREEN on the database password published in the repo: this guard
+    /// covered the two secrets it was written for, and nothing anywhere looked at the Postgres
+    /// credential. README step 2 doesn't name POSTGRES_PASSWORD either, so following the
+    /// documented procedure verbatim shipped it.
+    #[test]
+    fn prod_rejects_the_shipped_placeholder_database_password() {
+        let shipped = "postgres://eventsnap:CHANGE_ME_use_a_strong_password@db:5432/eventsnap";
+        let err = validate_secrets(true, REAL_SECRET, REAL_HASH, shipped).unwrap_err();
+        assert!(
+            err.to_string().contains("DATABASE_URL"),
+            "the refusal must name DATABASE_URL, not just fail: {err}"
+        );
+        // And it must point at the initdb trap, or the operator edits .env, restarts, and lands
+        // in a permanent auth-failure loop instead.
+        assert!(
+            err.to_string().contains("POSTGRES_PASSWORD"),
+            "the refusal must name POSTGRES_PASSWORD as the other half: {err}"
+        );
+    }
+
+    /// Every problem in ONE message. Reporting them one per boot made fixing two secrets cost two
+    /// restart cycles, on a stack where Caddy waits on the unhealthy app the whole time.
+    #[test]
+    fn prod_reports_every_placeholder_at_once() {
+        let err = validate_secrets(
+            true,
+            "change_me_to_a_random_64_byte_hex_string",
+            "$2y$12$placeholder_replace_me",
+            "postgres://eventsnap:CHANGE_ME_use_a_strong_password@db:5432/eventsnap",
+        )
+        .unwrap_err()
+        .to_string();
+        for expected in ["JWT_SECRET", "ADMIN_PASSWORD_HASH", "DATABASE_URL"] {
+            assert!(err.contains(expected), "{expected} missing from: {err}");
+        }
+        assert!(
+            err.contains("3 secret(s)"),
+            "the count must match what is listed: {err}"
+        );
+    }
+
+    #[test]
+    fn prod_accepts_real_secrets() {
+        assert!(validate_secrets(true, REAL_SECRET, REAL_HASH, REAL_DB_URL).is_ok());
+    }
+
+    /// A real password that happens to contain no placeholder substring must pass — including one
+    /// with URL-ish punctuation, so the guard can't be mistaken for a URL validator.
+    #[test]
+    fn prod_accepts_a_real_database_url_with_awkward_punctuation() {
+        assert!(
+            validate_secrets(
+                true,
+                REAL_SECRET,
+                REAL_HASH,
+                "postgres://eventsnap:aB3%24xY9-_.qW@db:5432/eventsnap"
+            )
+            .is_ok()
+        );
+    }
+
+    /// The e2e stack runs without APP_ENV=production, so none of this applies there — but assert
+    /// it, because a guard that tripped in e2e would be found the hard way.
+    #[test]
+    fn non_prod_ignores_a_placeholder_database_url() {
+        assert!(
+            validate_secrets(
+                false,
+                REAL_SECRET,
+                "",
+                "postgres://eventsnap:CHANGE_ME_use_a_strong_password@db:5432/eventsnap"
+            )
+            .is_ok()
+        );
+    }
+
+    #[test]
+    fn non_prod_tolerates_dev_sentinel() {
+        assert!(validate_secrets(false, DEV_JWT_SECRET_SENTINEL, "", REAL_DB_URL).is_ok());
+    }
+
+    #[test]
+    fn non_prod_still_rejects_short_non_sentinel_secret() {
+        assert!(validate_secrets(false, "tooshort", "", REAL_DB_URL).is_err());
+    }
+
+    #[test]
+    fn placeholder_detection_is_case_insensitive() {
+        // looks_placeholder lowercases before matching — an upper/mixed-case
+        // placeholder must still be rejected in prod.
+        assert!(
+            validate_secrets(
+                true,
+                "CHANGE_ME_TO_A_RANDOM_64_BYTE_HEX_STRING",
+                REAL_HASH,
+                REAL_DB_URL
+            )
+            .is_err()
+        );
+        assert!(
+            validate_secrets(
+                true,
+                REAL_SECRET,
+                "$2Y$12$PLACEHOLDER_replace_me",
+                REAL_DB_URL
+            )
+            .is_err()
+        );
+    }
+
+    #[test]
+    fn prod_len_boundary_at_32() {
+        // Exactly 32 non-placeholder chars is the minimum accepted; 31 is rejected.
+        const LEN_32: &str = "abcdefghijklmnopqrstuvwxyz012345";
+        const LEN_31: &str = "abcdefghijklmnopqrstuvwxyz01234";
+        assert_eq!(LEN_32.len(), 32);
+        assert_eq!(LEN_31.len(), 31);
+        assert!(validate_secrets(true, LEN_32, REAL_HASH, REAL_DB_URL).is_ok());
+        assert!(validate_secrets(true, LEN_31, REAL_HASH, REAL_DB_URL).is_err());
+    }
+}

backend/src/db.rs

@@ -1,20 +1,93 @@
 use anyhow::{Context, Result};
-use sqlx::postgres::PgPoolOptions;
 use sqlx::PgPool;
+use sqlx::postgres::PgPoolOptions;
 
 const DEFAULT_MAX_CONNECTIONS: u32 = 10;
 
+/// SQLSTATE for `invalid_password`.
+const PG_INVALID_PASSWORD: &str = "28P01";
+
+/// Turn the one connect failure with an unguessable cause into a self-explaining one.
+///
+/// `POSTGRES_PASSWORD` is honoured ONLY when Postgres initialises its data directory. Change it in
+/// `.env` afterwards and the app authenticates with the new password against a volume that still
+/// holds the old one — a permanent restart loop whose only symptom is
+/// `password authentication failed`.
+///
+/// The production secret guard makes that sequence NEARLY CERTAIN rather than rare: it stops the
+/// app on the first `docker compose up -d`, but not the `db` service in that same command, which
+/// initialises and bakes in whatever password was in `.env` at that moment. So the intended
+/// recovery — see the refusal, fix your secrets, boot again — is exactly the sequence that breaks
+/// it. Nothing in the error names the cause, and the remedy destroys data, so it is the last thing
+/// an operator should guess at.
+fn explain_auth_failure(err: &sqlx::Error) {
+    let is_auth_failure = match err {
+        sqlx::Error::Database(db) => db.code().as_deref() == Some(PG_INVALID_PASSWORD),
+        _ => false,
+    };
+    if !is_auth_failure {
+        return;
+    }
+    tracing::error!(
+        "Postgres rejected the credentials in DATABASE_URL (SQLSTATE {PG_INVALID_PASSWORD}).\n\
+         \n\
+         This almost always means POSTGRES_PASSWORD was changed AFTER the database volume was \
+         first created. Postgres applies that variable only when it initialises its data \
+         directory; editing .env and restarting does not change the stored password, so the two \
+         drift apart permanently.\n\
+         \n\
+         If the event has NOT started and you have no data worth keeping:\n\n    \
+         docker compose down -v && docker compose up -d\n\n\
+         (-v DELETES the database, the uploaded media and the exports. There is no undo.)\n\
+         \n\
+         If you DO have data: restore the old password into DATABASE_URL instead, or change the \
+         stored one with ALTER ROLE inside the running db container. Never reach for -v to fix a \
+         login problem on a live event."
+    );
+}
+
 pub async fn create_pool(database_url: &str) -> Result<PgPool> {
     let max_connections = std::env::var("DATABASE_MAX_CONNECTIONS")
         .ok()
         .and_then(|s| s.parse::<u32>().ok())
         .unwrap_or(DEFAULT_MAX_CONNECTIONS);
 
-    let pool = PgPoolOptions::new()
+    let pool = match PgPoolOptions::new()
         .max_connections(max_connections)
+        // Fail fast instead of parking. sqlx's default is 30s, which on a DB blip means every
+        // request AND all ~100 SSE session revalidations sit on the pool for half a minute
+        // before erroring — the app looks hung rather than degraded, and the backlog outlives
+        // the blip. Five seconds is far longer than a healthy acquire ever takes.
+        .acquire_timeout(std::time::Duration::from_secs(5))
+        // Keep a couple of connections warm so the first request after an idle stretch (the gap
+        // between setting the venue up and the guests arriving) doesn't pay TCP + auth.
+        .min_connections(2)
+        // Bound every statement server-side. Without this a single pathological query holds a
+        // pool slot indefinitely and no client-side timeout can take it back — the slot is only
+        // released when Postgres finishes. `lock_timeout` covers the same hazard for a row lock
+        // contended by, say, a release running against an in-flight upload.
+        .after_connect(|conn, _meta| {
+            Box::pin(async move {
+                // Two statements, two round-trips, deliberately. `sqlx::query` uses the extended
+                // query protocol, which permits exactly ONE statement per call — sending them as
+                // `SET a; SET b` makes every new connection fail, which surfaces as the pool
+                // never opening one at all and `create_pool` reporting a connect timeout.
+                sqlx::query("SET statement_timeout = '15s'")
+                    .execute(&mut *conn)
+                    .await?;
+                sqlx::query("SET lock_timeout = '5s'").execute(conn).await?;
+                Ok(())
+            })
+        })
         .connect(database_url)
         .await
-        .context("failed to connect to database")?;
+    {
+        Ok(pool) => pool,
+        Err(e) => {
+            explain_auth_failure(&e);
+            return Err(e).context("failed to connect to database");
+        }
+    };
 
     sqlx::migrate!()
         .run(&pool)

backend/src/error.rs

@@ -6,10 +6,25 @@ pub enum AppError {
     BadRequest(String),
     Unauthorized(String),
     Forbidden(String),
+    /// Uploads are temporarily locked (event closed / gallery released). Distinct from
+    /// `Forbidden` so the client can tell this REVERSIBLE 403 apart from a permanent one
+    /// (banned user, quota): the queued blob is kept and retried if the host reopens,
+    /// instead of being purged like a genuinely-terminal rejection.
+    UploadsLocked(String),
     NotFound(String),
     Conflict(String),
     /// Second field: optional retry-after seconds to include in the response.
     TooManyRequests(String, Option<u64>),
+    /// Per-user storage quota exhausted. Distinct from `TooManyRequests` (rate limit) so
+    /// the client can treat it as *terminal* (413, no retry) instead of backing off and
+    /// retrying a permanently-failing upload forever.
+    QuotaExceeded(String),
+    /// The server is temporarily unable to serve this request — currently only pool
+    /// saturation. Distinct from `Internal` because it is TRANSIENT and the client should be
+    /// told so: a 500 reads as "this request is broken", while a 503 + Retry-After reads as
+    /// "come back shortly", which is what the upload queue's retry classifier needs to make
+    /// the right call. Second field: optional retry-after seconds.
+    ServiceUnavailable(String, Option<u64>),
     Internal(anyhow::Error),
 }
 
@@ -19,9 +34,14 @@ impl AppError {
             Self::BadRequest(_) => (StatusCode::BAD_REQUEST, "bad_request"),
             Self::Unauthorized(_) => (StatusCode::UNAUTHORIZED, "unauthorized"),
             Self::Forbidden(_) => (StatusCode::FORBIDDEN, "forbidden"),
+            Self::UploadsLocked(_) => (StatusCode::FORBIDDEN, "uploads_locked"),
             Self::NotFound(_) => (StatusCode::NOT_FOUND, "not_found"),
             Self::Conflict(_) => (StatusCode::CONFLICT, "conflict"),
             Self::TooManyRequests(..) => (StatusCode::TOO_MANY_REQUESTS, "too_many_requests"),
+            Self::QuotaExceeded(_) => (StatusCode::PAYLOAD_TOO_LARGE, "quota_exceeded"),
+            Self::ServiceUnavailable(..) => {
+                (StatusCode::SERVICE_UNAVAILABLE, "service_unavailable")
+            }
             Self::Internal(_) => (StatusCode::INTERNAL_SERVER_ERROR, "internal_error"),
         }
     }
@@ -31,9 +51,12 @@ impl AppError {
             Self::BadRequest(msg)
             | Self::Unauthorized(msg)
             | Self::Forbidden(msg)
+            | Self::UploadsLocked(msg)
             | Self::NotFound(msg)
             | Self::Conflict(msg) => msg.clone(),
             Self::TooManyRequests(msg, _) => msg.clone(),
+            Self::ServiceUnavailable(msg, _) => msg.clone(),
+            Self::QuotaExceeded(msg) => msg.clone(),
             Self::Internal(err) => {
                 tracing::error!("internal error: {err:#}");
                 "Ein interner Fehler ist aufgetreten.".to_string()
@@ -45,13 +68,61 @@ impl AppError {
 impl IntoResponse for AppError {
     fn into_response(self) -> Response {
         let (status, code) = self.status_and_code();
-        let retry_after_secs = if let Self::TooManyRequests(_, Some(secs)) = &self {
-            Some(*secs)
-        } else {
-            None
+        // BOTH retry-carrying variants must be matched here. `message()` would fail to
+        // compile on a missing arm; this one would not — it would silently drop the header and
+        // the `retry_after_secs` body field, which is exactly the sort of omission that only
+        // shows up under the load the 503 exists for.
+        let retry_after_secs = match &self {
+            Self::TooManyRequests(_, secs) | Self::ServiceUnavailable(_, secs) => *secs,
+            _ => None,
         };
         let message = self.message();
 
+        // Log every 4xx. Until now they were invisible at ANY log level: tower_http's
+        // `ServerErrorsAsFailures` classifier counts a 4xx as a *success*, so it goes to
+        // `DefaultOnResponse` at DEBUG, and production runs at `info`. The consequence is that a
+        // misconfigured limit leaves no trace at all — if guests spend the evening hitting 429s
+        // on `upload_rate_per_hour`, or 413s on the storage quota, `docker compose logs` after
+        // the event contains nothing about it and the cause is unknowable.
+        //
+        // WARN rather than INFO because every variant here is a request that did not do what
+        // the guest asked. 5xx is excluded: `Internal` already logs with its full source chain
+        // in `message()` above, and the pool-exhaustion 503 logs at construction — logging again
+        // here would double every server-side failure.
+        //
+        // No request context is available: `into_response` receives only the error, so there is
+        // no path, method or user id to attach. Status + code + message is what can honestly be
+        // reported from here, and it is enough to see the SHAPE of a bad evening. Raising
+        // `tower_http` to DEBUG instead was considered and rejected — see the note in main.rs.
+        //
+        // `detail = ?message`, NOT `%message`. Two reasons, both learned the hard way:
+        //
+        //  * `message` is tracing's own reserved field for an event's format literal, so `%message`
+        //    printed unlabelled and would collide under a JSON layer.
+        //  * Debug formatting QUOTES AND ESCAPES the string, and several 4xx messages interpolate
+        //    attacker-chosen text — the guest's name in `Der Name "X" ist bereits vergeben.`, and
+        //    multipart/parse errors that echo their input. With Display formatting, a value
+        //    carrying a newline plus a plausible log prefix lets two unauthenticated requests
+        //    forge lines in the only forensic record an unattended event has.
+        //    `validate_display_name` now rejects control characters, so the name route is closed
+        //    at the source as well — but that is ONE input, and this line formats every 4xx
+        //    message in the app. Escaping here is what makes the guarantee general; do not
+        //    "simplify" it to `%message` on the grounds that names are already validated.
+        //
+        // 401 and 404 are logged at DEBUG rather than WARN. They carry no operator signal (an
+        // expired session, a mistyped URL) and they are the cheapest lines for a scanner to
+        // generate — at ~260 bytes each against the 30 MB the json-file driver retains
+        // (docker-compose.yml), a sustained flood could otherwise roll the whole window in
+        // minutes and destroy the post-event forensics this logging exists to provide.
+        if status.is_client_error() {
+            let noisy = status == StatusCode::UNAUTHORIZED || status == StatusCode::NOT_FOUND;
+            if noisy {
+                tracing::debug!(status = status.as_u16(), code, detail = ?message, "request rejected");
+            } else {
+                tracing::warn!(status = status.as_u16(), code, detail = ?message, "request rejected");
+            }
+        }
+
         let mut body = serde_json::json!({
             "error": code,
             "message": message,
@@ -62,10 +133,11 @@ impl IntoResponse for AppError {
         }
 
         let mut resp = (status, axum::Json(body)).into_response();
-        if let Some(secs) = retry_after_secs {
-            if let Ok(val) = axum::http::HeaderValue::from_str(&secs.to_string()) {
-                resp.headers_mut().insert(axum::http::header::RETRY_AFTER, val);
-            }
+        if let Some(secs) = retry_after_secs
+            && let Ok(val) = axum::http::HeaderValue::from_str(&secs.to_string())
+        {
+            resp.headers_mut()
+                .insert(axum::http::header::RETRY_AFTER, val);
         }
         resp
     }
@@ -79,6 +151,121 @@ impl From<anyhow::Error> for AppError {
 
 impl From<sqlx::Error> for AppError {
     fn from(err: sqlx::Error) -> Self {
-        Self::Internal(err.into())
+        match err {
+            // Pool saturation is load, not a bug. Reporting it as a 500 was actively harmful:
+            // the frontend's upload-queue classifier treats 5xx as transient and retries, so
+            // the retries piled straight back into the saturated pool with no Retry-After to
+            // pace them. A 503 says the same thing honestly and carries the backoff.
+            //
+            // `PoolClosed` stays `Internal` — it only happens during shutdown, where a 503
+            // would invite a retry against a server that is going away.
+            sqlx::Error::PoolTimedOut => {
+                tracing::warn!("database pool exhausted; shedding a request with 503");
+                Self::ServiceUnavailable(
+                    "Server ist gerade ausgelastet. Bitte versuche es in ein paar Sekunden erneut."
+                        .into(),
+                    Some(POOL_TIMEOUT_RETRY_AFTER_SECS),
+                )
+            }
+            other => Self::Internal(other.into()),
+        }
+    }
+}
+
+/// Retry-After for a shed request. Short: pool saturation clears in seconds once the queue
+/// drains, and a long value would make a brief spike feel like an outage.
+const POOL_TIMEOUT_RETRY_AFTER_SECS: u64 = 3;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// `into_response` extracts `retry_after_secs` by MATCHING ON VARIANTS, so unlike
+    /// `message()` a missing arm is not a compile error — it silently drops the header. Pin the
+    /// behaviour for both retry-carrying variants.
+    #[test]
+    fn both_retry_carrying_variants_emit_retry_after() {
+        for err in [
+            AppError::TooManyRequests("slow down".into(), Some(42)),
+            AppError::ServiceUnavailable("busy".into(), Some(3)),
+        ] {
+            let expected = match &err {
+                AppError::TooManyRequests(_, Some(s)) | AppError::ServiceUnavailable(_, Some(s)) => {
+                    s.to_string()
+                }
+                _ => unreachable!(),
+            };
+            let resp = err.into_response();
+            assert_eq!(
+                resp.headers()
+                    .get(axum::http::header::RETRY_AFTER)
+                    .and_then(|v| v.to_str().ok()),
+                Some(expected.as_str()),
+                "a shed/throttled client must be told when to come back"
+            );
+        }
+    }
+
+    /// 4xx must be logged and 5xx must not be logged HERE — `Internal` logs its source chain in
+    /// `message()` and the pool-exhaustion 503 logs at construction, so a second line in
+    /// `into_response` would double every server-side failure in the post-event logs.
+    ///
+    /// The guard is `status.is_client_error()`, so this pins the classification rather than the
+    /// logging itself (which needs a subscriber to observe).
+    #[test]
+    fn only_client_errors_are_in_the_logged_band() {
+        for err in [
+            AppError::BadRequest("x".into()),
+            AppError::Unauthorized("x".into()),
+            AppError::Forbidden("x".into()),
+            AppError::UploadsLocked("x".into()),
+            AppError::NotFound("x".into()),
+            AppError::Conflict("x".into()),
+            AppError::TooManyRequests("x".into(), Some(1)),
+            AppError::QuotaExceeded("x".into()),
+        ] {
+            let (status, _) = err.status_and_code();
+            assert!(
+                status.is_client_error(),
+                "{status} should be in the 4xx band this logs"
+            );
+        }
+
+        for err in [
+            AppError::ServiceUnavailable("x".into(), Some(3)),
+            AppError::Internal(anyhow::anyhow!("boom")),
+        ] {
+            let (status, _) = err.status_and_code();
+            assert!(
+                !status.is_client_error(),
+                "{status} logs elsewhere; logging it here would double it"
+            );
+        }
+    }
+
+    /// Pool saturation is load, not a bug. A 500 makes the frontend's retry classifier pile
+    /// straight back into the saturated pool with no backoff to pace it.
+    #[test]
+    fn pool_exhaustion_sheds_with_503_but_shutdown_does_not() {
+        let shed: AppError = sqlx::Error::PoolTimedOut.into();
+        assert_eq!(
+            shed.status_and_code(),
+            (StatusCode::SERVICE_UNAVAILABLE, "service_unavailable")
+        );
+
+        // PoolClosed only happens during shutdown; a 503 there would invite a retry against a
+        // server that is going away.
+        let closing: AppError = sqlx::Error::PoolClosed.into();
+        assert_eq!(
+            closing.status_and_code(),
+            (StatusCode::INTERNAL_SERVER_ERROR, "internal_error")
+        );
+
+        // Everything else must keep its existing mapping.
+        let missing: AppError = sqlx::Error::RowNotFound.into();
+        assert_eq!(
+            missing.status_and_code(),
+            (StatusCode::INTERNAL_SERVER_ERROR, "internal_error")
+        );
     }
 }

backend/src/handlers/admin.rs

@@ -1,16 +1,16 @@
 use std::collections::HashMap;
 use std::time::Duration;
 
-use axum::extract::State;
-use axum::http::{HeaderMap, StatusCode};
 use axum::Json;
+use axum::extract::{Query, State};
+use axum::http::StatusCode;
 use serde::{Deserialize, Serialize};
-use sysinfo::System;
+use uuid::Uuid;
 
 use crate::auth::middleware::RequireAdmin;
 use crate::error::AppError;
 use crate::services::config;
-use crate::services::rate_limiter::client_ip;
+use crate::services::sse_tickets::TicketKind;
 use crate::state::AppState;
 
 // ── DTOs ─────────────────────────────────────────────────────────────────────
@@ -46,19 +46,17 @@ pub async fn get_stats(
         .await?
         .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
 
-    let (user_count,): (i64,) =
-        sqlx::query_as("SELECT COUNT(*) FROM \"user\" WHERE event_id = $1")
+    let (user_count,): (i64,) = sqlx::query_as("SELECT COUNT(*) FROM \"user\" WHERE event_id = $1")
+        .bind(event.id)
+        .fetch_one(&state.pool)
+        .await?;
+
+    let (upload_count,): (i64,) =
+        sqlx::query_as("SELECT COUNT(*) FROM upload WHERE event_id = $1 AND deleted_at IS NULL")
             .bind(event.id)
             .fetch_one(&state.pool)
             .await?;
 
-    let (upload_count,): (i64,) = sqlx::query_as(
-        "SELECT COUNT(*) FROM upload WHERE event_id = $1 AND deleted_at IS NULL",
-    )
-    .bind(event.id)
-    .fetch_one(&state.pool)
-    .await?;
-
     let (comment_count,): (i64,) = sqlx::query_as(
         "SELECT COUNT(*) FROM comment c
          JOIN upload u ON u.id = c.upload_id
@@ -68,23 +66,12 @@ pub async fn get_stats(
     .fetch_one(&state.pool)
     .await?;
 
-    // Disk usage via sysinfo
-    let mut sys = System::new();
-    sys.refresh_all();
-
-    let media_path = state.config.media_path.to_string_lossy().to_string();
-    let (disk_total, disk_free) = sysinfo::Disks::new_with_refreshed_list()
-        .iter()
-        .find(|d| media_path.starts_with(d.mount_point().to_string_lossy().as_ref()))
-        .map(|d| (d.total_space(), d.available_space()))
-        .unwrap_or_else(|| {
-            // Fall back to the root disk
-            sysinfo::Disks::new_with_refreshed_list()
-                .iter()
-                .find(|d| d.mount_point().to_string_lossy() == "/")
-                .map(|d| (d.total_space(), d.available_space()))
-                .unwrap_or((0, 0))
-        });
+    // Disk usage from the shared cache (unknown mount → zeros, same as before).
+    let (disk_total, disk_free) = state
+        .disk_cache
+        .snapshot(&state.config.media_path)
+        .map(|d| (d.total, d.free))
+        .unwrap_or((0, 0));
 
     let disk_used = disk_total.saturating_sub(disk_free);
 
@@ -102,14 +89,17 @@ pub async fn get_config(
     State(state): State<AppState>,
     RequireAdmin(_auth): RequireAdmin,
 ) -> Result<Json<HashMap<String, String>>, AppError> {
-    let rows: Vec<(String, String)> =
-        sqlx::query_as("SELECT key, value FROM config ORDER BY key")
-            .fetch_all(&state.pool)
-            .await?;
+    let rows: Vec<(String, String)> = sqlx::query_as("SELECT key, value FROM config ORDER BY key")
+        .fetch_all(&state.pool)
+        .await?;
 
     Ok(Json(rows.into_iter().collect()))
 }
 
+/// Documents the wire shape of `PATCH /admin/config` (a flat `{key: value}` object).
+/// `patch_config` extracts the `HashMap` directly rather than going through this newtype, so it is
+/// never constructed in Rust — it stays as the serde-derived description of the request body.
+#[allow(dead_code)]
 #[derive(Deserialize)]
 pub struct PatchConfigRequest(pub HashMap<String, String>);
 
@@ -121,15 +111,38 @@ pub async fn patch_config(
     // Numeric keys validated as f64; boolean keys validated as truthy strings; the
     // privacy note is free text. Splitting these explicitly is verbose but makes the
     // failure mode for typos obvious (`Unbekannter Schlüssel: ...`).
-    const NUMERIC_KEYS: &[&str] = &[
-        "max_image_size_mb",
-        "max_video_size_mb",
-        "upload_rate_per_hour",
-        "feed_rate_per_min",
-        "export_rate_per_day",
-        "quota_tolerance",
-        "estimated_guest_count",
-        "compression_concurrency",
+    // (key, integer_only, min, max). Ranges reject values that `parse::<f64>` would
+    // accept but that silently revert to the hardcoded default at read time
+    // (get_usize/get_i64 can't parse negatives/NaN/fractionals). `compression_concurrency`
+    // is intentionally absent — it's read once at boot, so a live edit was a no-op.
+    const NUMERIC_SPECS: &[(&str, bool, f64, f64)] = &[
+        ("max_image_size_mb", true, 1.0, 1024.0),
+        ("max_video_size_mb", true, 1.0, 10240.0),
+        ("upload_rate_per_hour", true, 1.0, 100_000.0),
+        ("feed_rate_per_min", true, 1.0, 100_000.0),
+        ("export_rate_per_day", true, 1.0, 100_000.0),
+        // Loose per-IP ceiling on /join. The real anti-spam bucket is per (ip, name); this
+        // only bounds raw volume from one source, so it must stay well above the size of a
+        // party arriving at once (see migration 017).
+        ("join_ip_rate_per_min", true, 1.0, 100_000.0),
+        // Same shape for /recover: the per-(ip, name) bucket is the anti-guessing control,
+        // this only bounds a name-cycling flood in front of a cost-12 bcrypt (migration 019).
+        ("recover_ip_rate_per_min", true, 1.0, 100_000.0),
+        // Aggregate ceiling on likes + comments + comment deletions, per user per minute.
+        // These were the only mutating endpoints with no limit at all (migration 020).
+        ("social_rate_per_min", true, 1.0, 100_000.0),
+        ("quota_tolerance", false, 0.0, 1.0),
+        ("estimated_guest_count", true, 1.0, 1_000_000.0),
+        // The three limiters migration 025 introduced. All are READ at runtime
+        // (`upload.rs` for the edit limiter, `auth/handlers.rs` for the other two) and 025
+        // INSERTs all of them into `config`, so `GET /admin/config` listed them while
+        // `PATCH /admin/config` answered "Unbekannter Konfigurationsschlüssel" — the same
+        // dead-key defect the comment under BOOL_KEYS says was fixed for the two login
+        // toggles. These are precisely the knobs an operator reaches for while abuse is
+        // happening, which is the one moment a restart to change them is unaffordable.
+        ("upload_edit_rate_per_min", true, 1.0, 100_000.0),
+        ("recover_name_rate_per_15min", true, 1.0, 100_000.0),
+        ("pin_reset_ip_rate_per_min", true, 1.0, 100_000.0),
     ];
     const BOOL_KEYS: &[&str] = &[
         "rate_limits_enabled",
@@ -137,23 +150,84 @@ pub async fn patch_config(
         "feed_rate_enabled",
         "export_rate_enabled",
         "join_rate_enabled",
+        // These two per-area rate toggles are HONOURED by their handlers (auth/handlers.rs reads
+        // `admin_login_rate_enabled` and `recover_rate_enabled`, both defaulting true) but were
+        // missing from this allowlist — so the switch existed in code and could never be flipped.
+        "admin_login_rate_enabled",
+        "recover_rate_enabled",
+        "social_rate_enabled",
+        // Read by `upload::edit_upload`, inserted by migration 025, and until now unreachable
+        // from this endpoint — see the note in NUMERIC_SPECS.
+        "upload_edit_rate_enabled",
         "quota_enabled",
         "storage_quota_enabled",
         "upload_count_quota_enabled",
     ];
-    const TEXT_KEYS: &[&str] = &["privacy_note"];
+    const TEXT_KEYS: &[&str] = &[
+        "privacy_note",
+        "theme_preset",
+        "theme_primary",
+        "theme_accent",
+    ];
     const PRIVACY_NOTE_MAX_LEN: usize = 16 * 1024; // 16 KiB free text is plenty
+    // Preset ids the frontend knows how to render (mirror of PRESETS in
+    // frontend/src/lib/theme/palette.ts). "custom" means "use the theme_primary/accent
+    // seeds verbatim". Kept in sync by hand — a new preset must be added in both places.
+    const THEME_PRESETS: &[&str] = &[
+        "champagne-gold",
+        "rose",
+        "sage",
+        "dusk-blue",
+        "classic-silver",
+        "custom",
+    ];
 
     let mut privacy_note_changed = false;
+    let mut theme_changed = false;
 
+    // Validate every key first so a bad value in the batch can't leave a partial
+    // update behind — validation must fully precede any write.
     for (key, value) in &body {
         let key_str = key.as_str();
-        if NUMERIC_KEYS.contains(&key_str) {
-            if value.parse::<f64>().is_err() {
+        if let Some(&(_, integer_only, min, max)) =
+            NUMERIC_SPECS.iter().find(|(k, ..)| *k == key_str)
+        {
+            let n = value.trim().parse::<f64>().ok().filter(|n| n.is_finite());
+            let n = match n {
+                Some(n) => n,
+                None => {
+                    return Err(AppError::BadRequest(format!(
+                        "Ungültiger Wert für {key}: muss eine Zahl sein."
+                    )));
+                }
+            };
+            if integer_only && n.fract() != 0.0 {
                 return Err(AppError::BadRequest(format!(
-                    "Ungültiger Wert für {key}: muss eine Zahl sein."
+                    "Ungültiger Wert für {key}: muss eine ganze Zahl sein."
                 )));
             }
+            if n < min || n > max {
+                return Err(AppError::BadRequest(format!(
+                    "Wert für {key} liegt außerhalb des zulässigen Bereichs ({min}–{max})."
+                )));
+            }
+            // Zero is in range and catastrophic. `quota_tolerance` is the multiplier in
+            // `free_disk * tolerance / active_uploaders`, so 0 makes every per-user limit 0 and
+            // refuses EVERY upload — mid-event, with "Du hast dein Upload-Limit für dieses Event
+            // erreicht", an error naming the wrong cause entirely. `storage_quota_enabled` is the
+            // intended off-switch.
+            //
+            // Rejecting the value rather than raising the floor: very small tolerances are
+            // legitimate (they are how a large disk is throttled down to a sensible per-guest
+            // ceiling, and how the e2e quota tests steer it — around 1e-5 on a 174 GB volume), so
+            // a floor of, say, 0.01 would forbid real configurations to prevent one typo.
+            if key_str == "quota_tolerance" && n == 0.0 {
+                return Err(AppError::BadRequest(
+                    "quota_tolerance = 0 würde jeden Upload blockieren. Zum Abschalten der \
+                     Speicher-Quote stattdessen „Speicher-Quote aktiv“ ausschalten."
+                        .into(),
+                ));
+            }
         } else if BOOL_KEYS.contains(&key_str) {
             match value.trim().to_ascii_lowercase().as_str() {
                 "true" | "false" | "1" | "0" | "yes" | "no" | "on" | "off" => {}
@@ -164,42 +238,83 @@ pub async fn patch_config(
                 }
             }
         } else if TEXT_KEYS.contains(&key_str) {
-            if value.len() > PRIVACY_NOTE_MAX_LEN {
+            // Count characters, not bytes — the message says "Zeichen" and a
+            // multi-byte grapheme shouldn't count against the limit multiple times.
+            if value.chars().count() > PRIVACY_NOTE_MAX_LEN {
                 return Err(AppError::BadRequest(format!(
                     "Wert für {key} ist zu lang (max. {PRIVACY_NOTE_MAX_LEN} Zeichen)."
                 )));
             }
-            if key_str == "privacy_note" {
-                privacy_note_changed = true;
+            match key_str {
+                "privacy_note" => privacy_note_changed = true,
+                "theme_preset" => {
+                    if !THEME_PRESETS.contains(&value.trim()) {
+                        return Err(AppError::BadRequest(format!("Ungültiges Theme: {value}.")));
+                    }
+                    theme_changed = true;
+                }
+                "theme_primary" | "theme_accent" => {
+                    if !is_hex_color(value.trim()) {
+                        return Err(AppError::BadRequest(format!(
+                            "Ungültige Farbe für {key}: muss #rrggbb sein."
+                        )));
+                    }
+                    theme_changed = true;
+                }
+                _ => {}
             }
         } else {
             return Err(AppError::BadRequest(format!(
                 "Unbekannter Konfigurationsschlüssel: {key}"
             )));
         }
+    }
 
+    // Apply all writes in one transaction — the batch is all-or-nothing.
+    let mut tx = state.pool.begin().await?;
+    for (key, value) in &body {
         sqlx::query(
             "INSERT INTO config (key, value, updated_at) VALUES ($1, $2, NOW())
              ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()",
         )
         .bind(key)
         .bind(value)
-        .execute(&state.pool)
+        .execute(&mut *tx)
         .await?;
     }
+    tx.commit().await?;
+
+    // The config cache must reflect this write on the very next read (tests PATCH then
+    // immediately assert the new value takes effect). Invalidate synchronously here —
+    // the TTL is only a backstop and must not be relied on for correctness.
+    state.config_cache.invalidate();
 
     // Notify all clients that a publicly-readable config value changed so their stores
     // (e.g. the privacy note in My Account) refresh without a manual reload.
-    if privacy_note_changed {
+    if privacy_note_changed || theme_changed {
+        let mut keys: Vec<&str> = Vec::new();
+        if privacy_note_changed {
+            keys.push("privacy_note");
+        }
+        if theme_changed {
+            keys.push("theme");
+        }
         let _ = state.sse_tx.send(crate::state::SseEvent::new(
             "event-updated",
-            serde_json::json!({ "keys": ["privacy_note"] }).to_string(),
+            serde_json::json!({ "keys": keys }).to_string(),
         ));
     }
 
     Ok(StatusCode::NO_CONTENT)
 }
 
+/// A strict `#rrggbb` hex-colour check (6 hex digits, leading `#`). Deliberately not
+/// accepting shorthand/`#rgba` so the value is safe to drop straight into CSS.
+fn is_hex_color(s: &str) -> bool {
+    let bytes = s.as_bytes();
+    bytes.len() == 7 && bytes[0] == b'#' && bytes[1..].iter().all(|b| b.is_ascii_hexdigit())
+}
+
 pub async fn get_export_jobs(
     State(state): State<AppState>,
     RequireAdmin(_auth): RequireAdmin,
@@ -223,53 +338,175 @@ pub async fn get_export_jobs(
 
 // ── Export download endpoints (authenticated guests) ─────────────────────────
 
-pub async fn download_zip(
+#[derive(Deserialize)]
+pub struct DownloadQuery {
+    pub ticket: String,
+}
+
+/// Mint a short-lived ticket for a browser-driven export download. The download
+/// is a top-level navigation so the multi-GB ZIP streams straight to disk instead
+/// of being buffered in memory by `fetch()` + `blob()` — but a navigation can't
+/// carry an `Authorization` header, so the client exchanges its Bearer token for
+/// an opaque ticket here, then hits `/export/zip?ticket=...`. Reuses the same
+/// single-use, 30s-TTL store as the SSE stream.
+#[derive(serde::Deserialize)]
+pub struct ExportTicketQuery {
+    /// Which archive the ticket is for — `zip` or `html`. Optional so an older client that
+    /// doesn't send it keeps working; it simply skips the pre-check it doesn't know to ask for.
+    #[serde(default)]
+    pub kind: Option<String>,
+}
+
+pub async fn export_ticket(
     State(state): State<AppState>,
-    _auth: crate::auth::middleware::AuthUser,
-    headers: HeaderMap,
-) -> Result<axum::response::Response, AppError> {
-    enforce_export_rate(&state, &headers).await?;
+    axum::extract::Query(q): axum::extract::Query<ExportTicketQuery>,
+    auth: crate::auth::middleware::AuthUser,
+) -> Result<Json<serde_json::Value>, AppError> {
+    // NOTE: intentionally NOT gated on `is_banned`. A banned user keeps *read* access
+    // by design (USER_JOURNEYS §10.3, FEATURES: "Can still download the export once
+    // released — Spec design choice"). The export is read-only, so it stays available
+    // to them, consistent with the read-only-ban model.
 
-    let event = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
-        .await?
-        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
-
-    if !event.export_zip_ready {
-        return Err(AppError::NotFound(
-            "Der ZIP-Export ist noch nicht verfügbar.".into(),
-        ));
+    // The rate limit is enforced HERE rather than on the download itself, and that placement is
+    // the whole point: the download is an iframe navigation, so its response is invisible to the
+    // page. Limiting it there meant a guest over the limit tapped "Herunterladen", the ticket
+    // POST returned 200, the iframe silently received a 429, and absolutely nothing happened —
+    // forever, with no explanation, on the one screen that is the emotional payoff of the app.
+    // Minting is a normal `fetch`, so a 429 here reaches the user as a German message.
+    //
+    // Moving it does not weaken the limit: tickets are single-use with a 30s TTL and can only be
+    // obtained from this authenticated endpoint, so one mint is at most one download.
+    // Confirm the archive actually EXISTS before spending anything on it.
+    //
+    // `export_status` — which is what enables the Download button — reports `done` from
+    // `export_job`, while the download resolves through `export_current.file_path` plus a
+    // `Path::exists()`. Those are different sources of truth and can legitimately disagree: a
+    // row can say done while the file is gone, or an epoch bump can retire it between the page
+    // rendering and the guest tapping. When they disagreed the guest got the worst possible
+    // shape of failure — a green "Download gestartet" toast, a consumed single-use ticket, one
+    // of only three daily slots spent, and nothing in their Downloads folder, repeatable until
+    // the day's allowance was gone.
+    //
+    // Checking here, before `enforce_export_rate`, turns that into an honest error on a plain
+    // `fetch` that the existing `toastError` path already renders. This is NOT the HEAD probe
+    // ruled out elsewhere: it reads the same indexed row the download will read and touches no
+    // ticket, so it cannot consume anything.
+    if let Some(kind) = q.kind.as_deref() {
+        let export_type = match kind {
+            "zip" => "zip",
+            "html" => "html",
+            other => {
+                return Err(AppError::BadRequest(format!(
+                    "Unbekannter Export-Typ: {other}"
+                )));
+            }
+        };
+        let msg = if export_type == "zip" {
+            "Der ZIP-Export ist noch nicht verfügbar."
+        } else {
+            "Der HTML-Export ist noch nicht verfügbar."
+        };
+        resolve_export_file(&state, export_type, msg).await?;
     }
 
-    let path = state.config.media_path.join("exports").join("Gallery.zip");
+    enforce_export_rate(&state, auth.user_id).await?;
+
+    // `issue` returns None when the ticket store is at capacity. Unwrapping it into the JSON body
+    // serialized `{"ticket": null}` with a 200 — so `api.post` resolved happily, the page toasted
+    // success, the iframe navigated to `?ticket=null`, and one of the guest's three DAILY
+    // downloads had already been charged above. That is precisely the phantom-success failure
+    // this endpoint's pre-validation was added to eliminate, arriving through the other door.
+    // 503 + Retry-After, matching how `sse::issue_ticket` answers the identical condition.
+    let ticket = state
+        .sse_tickets
+        .issue(auth.token_hash, TicketKind::Download)
+        .ok_or_else(|| {
+            AppError::ServiceUnavailable(
+                "Server ist gerade ausgelastet. Bitte versuch es in einem Moment erneut.".into(),
+                Some(30),
+            )
+        })?;
+    Ok(Json(serde_json::json!({ "ticket": ticket })))
+}
+
+/// Validate a download ticket (single-use) and confirm its session still exists.
+/// Resolve a single-use download ticket to the user who minted it. The caller needs the
+/// id to key the export rate limit per-user (see `enforce_export_rate`).
+async fn authenticate_download_ticket(state: &AppState, ticket: &str) -> Result<Uuid, AppError> {
+    let token_hash = state
+        .sse_tickets
+        .consume(ticket, TicketKind::Download)
+        .ok_or_else(|| AppError::Unauthorized("Ticket ungültig oder abgelaufen.".into()))?;
+    let session = crate::models::session::Session::find_by_token_hash(&state.pool, &token_hash)
+        .await
+        .map_err(|e| AppError::Internal(e.into()))?
+        .ok_or_else(|| AppError::Unauthorized("Sitzung nicht gefunden.".into()))?;
+    Ok(session.user_id)
+}
+
+pub async fn download_zip(
+    State(state): State<AppState>,
+    Query(q): Query<DownloadQuery>,
+) -> Result<axum::response::Response, AppError> {
+    // Ticket validation only — the rate limit was charged at mint time, where a 429 is visible
+    // to the page. Charging it again here would cost every download two slots.
+    authenticate_download_ticket(&state, &q.ticket).await?;
+
+    let path =
+        resolve_export_file(&state, "zip", "Der ZIP-Export ist noch nicht verfügbar.").await?;
+    serve_file(path, "Gallery.zip", "application/zip").await
+}
+
+/// Resolve the on-disk path of the CURRENT export generation — readiness check and path lookup in
+/// ONE read, through the `export_current` view (migration 014).
+///
+/// This used to be two statements: the caller checked `event.export_zip_ready`, then this fetched
+/// `export_job.file_path`. A reopen landing between them served a keepsake that should have 404'd —
+/// the same stale-keepsake class, leaking through the read path, and it existed only because
+/// readiness was a stored copy rather than a derivation. `export_current` gives both facts from one
+/// consistent snapshot: it yields a row only when the event is released AND the job is `done` at the
+/// event's current epoch, so "is it ready" and "which file" can no longer disagree.
+async fn resolve_export_file(
+    state: &AppState,
+    export_type: &str,
+    not_ready_msg: &str,
+) -> Result<std::path::PathBuf, AppError> {
+    let file_path: Option<(Option<String>,)> = sqlx::query_as(
+        "SELECT c.file_path FROM export_current c
+         JOIN event e ON e.id = c.event_id
+         WHERE e.slug = $1 AND c.type = $2::export_type AND c.status = 'done'",
+    )
+    .bind(&state.config.event_slug)
+    .bind(export_type)
+    .fetch_optional(&state.pool)
+    .await
+    .map_err(|e| AppError::Internal(e.into()))?;
+
+    let Some((Some(rel),)) = file_path else {
+        return Err(AppError::NotFound(not_ready_msg.into()));
+    };
+
+    // `file_path` is stored as `exports/<name>`; the base dir is already `export_path`, so
+    // join only the file name (defends against any absolute/`..` content too).
+    let name = std::path::Path::new(&rel)
+        .file_name()
+        .ok_or_else(|| AppError::NotFound("Exportdatei nicht gefunden.".into()))?;
+    let path = state.config.export_path.join(name);
     if !path.exists() {
         return Err(AppError::NotFound("Exportdatei nicht gefunden.".into()));
     }
-
-    serve_file(path, "Gallery.zip", "application/zip").await
+    Ok(path)
 }
 
 pub async fn download_html(
     State(state): State<AppState>,
-    _auth: crate::auth::middleware::AuthUser,
-    headers: HeaderMap,
+    Query(q): Query<DownloadQuery>,
 ) -> Result<axum::response::Response, AppError> {
-    enforce_export_rate(&state, &headers).await?;
-
-    let event = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
-        .await?
-        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
-
-    if !event.export_html_ready {
-        return Err(AppError::NotFound(
-            "Der HTML-Export ist noch nicht verfügbar.".into(),
-        ));
-    }
-
-    let path = state.config.media_path.join("exports").join("Memories.zip");
-    if !path.exists() {
-        return Err(AppError::NotFound("Exportdatei nicht gefunden.".into()));
-    }
+    // See `download_zip`: the limit is charged at ticket mint, where the client can see it.
+    authenticate_download_ticket(&state, &q.ticket).await?;
 
+    let path =
+        resolve_export_file(&state, "html", "Der HTML-Export ist noch nicht verfügbar.").await?;
     serve_file(path, "Memories.zip", "application/zip").await
 }
 
@@ -279,7 +516,7 @@ async fn serve_file(
     content_type: &str,
 ) -> Result<axum::response::Response, AppError> {
     use axum::body::Body;
-    use axum::http::{header, Response, StatusCode};
+    use axum::http::{Response, StatusCode, header};
     use tokio_util::io::ReaderStream;
 
     let file = tokio::fs::File::open(&path)
@@ -315,8 +552,24 @@ pub async fn export_status(
 
     let released = event.export_released_at.is_some();
 
-    let jobs: Vec<(String, String, i16)> = sqlx::query_as(
-        "SELECT type::text, status::text, progress_pct FROM export_job WHERE event_id = $1",
+    // ONE statement: the epoch comparison happens inside the query, against a single snapshot.
+    // Binding the epoch read by a previous statement would let a release/regeneration commit in
+    // between and yield `{released: true, zip: locked, html: locked}` — a state that never existed.
+    //
+    // Only jobs at the CURRENT epoch are reported. A row left behind by a retired generation (a
+    // worker superseded mid-run) is meaningless — surfacing its frozen `running`/77% would show a
+    // progress bar that never moves for a keepsake nobody is building. It reads as "locked" (no
+    // current job), which is exactly what it is.
+    // `error_message` is carried here, not just on the admin dashboard's job list. The host is the
+    // one who releases the keepsake and the one who owns the "Erneut versuchen" button, but this
+    // endpoint used to hand them a bare `failed` — so a fully actionable reason (notably the disk
+    // preflight's "needs X GB, Y GB free") was written to the row and then shown to nobody who
+    // could act on it. An admin-only diagnostic is not a diagnostic for the person on the spot.
+    let jobs: Vec<(String, String, i16, Option<String>)> = sqlx::query_as(
+        "SELECT j.type::text, j.status::text, j.progress_pct, j.error_message
+           FROM export_job j
+           JOIN event e ON e.id = j.event_id
+          WHERE e.id = $1 AND j.epoch = e.export_epoch",
     )
     .bind(event.id)
     .fetch_all(&state.pool)
@@ -324,11 +577,21 @@ pub async fn export_status(
 
     let job_status = |type_name: &str| {
         jobs.iter()
-            .find(|(t, _, _)| t == type_name)
-            .map(|(_, status, pct)| {
-                serde_json::json!({ "status": status, "progress_pct": pct })
+            .find(|(t, _, _, _)| t == type_name)
+            .map(|(_, status, pct, err)| {
+                serde_json::json!({
+                    "status": status,
+                    "progress_pct": pct,
+                    // Only on a failure. A stale message left on a row that has since been re-armed
+                    // would otherwise show an error next to a running progress bar.
+                    "error_message": if status == "failed" { err.clone() } else { None },
+                })
+            })
+            .unwrap_or_else(|| {
+                serde_json::json!({
+                    "status": "locked", "progress_pct": 0, "error_message": null,
+                })
             })
-            .unwrap_or_else(|| serde_json::json!({ "status": "locked", "progress_pct": 0 }))
     };
 
     Ok(Json(serde_json::json!({
@@ -341,21 +604,29 @@ pub async fn export_status(
 /// Centralised guard for the export rate limit. Same pattern as upload/feed: master
 /// switch + per-endpoint switch + numeric value, all stored in `config` and read on
 /// each request.
-async fn enforce_export_rate(state: &AppState, headers: &HeaderMap) -> Result<(), AppError> {
-    let rate_limits_on = config::get_bool(&state.pool, "rate_limits_enabled", true).await;
-    let export_rate_on = config::get_bool(&state.pool, "export_rate_enabled", true).await;
+async fn enforce_export_rate(state: &AppState, user_id: Uuid) -> Result<(), AppError> {
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let export_rate_on = config::get_bool(&state.config_cache, "export_rate_enabled", true).await;
     if !(rate_limits_on && export_rate_on) {
         return Ok(());
     }
-    let ip = client_ip(headers, "unknown");
-    let limit = config::get_usize(&state.pool, "export_rate_per_day", 3).await;
-    if !state
-        .rate_limiter
-        .check(format!("export:{ip}"), limit, Duration::from_secs(86400))
-    {
+    let limit = config::get_usize(&state.config_cache, "export_rate_per_day", 3).await;
+    // Keyed per-user. This was the worst of the IP-keyed limiters: 3 downloads per DAY
+    // shared across every guest behind the venue's public IP, so the fourth person to
+    // fetch their keepsake was locked out until the next day.
+    if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+        format!("export:{user_id}"),
+        limit,
+        Duration::from_secs(86400),
+    ) {
+        // Names the real window. The generic "warte kurz" wording this used to share with the
+        // per-minute limiters is actively wrong here — the bucket is a DAY, so a guest told to
+        // wait a moment would keep tapping a button that cannot work again until tomorrow.
         return Err(AppError::TooManyRequests(
-            "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-            None,
+            "Du hast das Tageslimit für Downloads erreicht. Versuch es später noch einmal — \
+             deine Galerie bleibt gespeichert."
+                .into(),
+            Some(retry_after_secs),
         ));
     }
     Ok(())

backend/src/handlers/feed.rs

@@ -1,8 +1,7 @@
 use std::time::Duration;
 
-use axum::extract::{Query, State};
-use axum::http::HeaderMap;
 use axum::Json;
+use axum::extract::{Query, State};
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
@@ -10,15 +9,49 @@ use uuid::Uuid;
 use crate::auth::middleware::AuthUser;
 use crate::error::AppError;
 use crate::services::config;
-use crate::services::media_token;
-use crate::services::rate_limiter::client_ip;
 use crate::state::AppState;
 
 #[derive(Deserialize)]
 pub struct FeedQuery {
     pub cursor: Option<Uuid>,
     pub limit: Option<i64>,
+    /// Single tag (list view). Kept alongside `hashtags` so existing callers keep working.
     pub hashtag: Option<String>,
+    /// Comma-separated tags, combined with **OR** — the grid's chip semantics
+    /// (USER_JOURNEYS §8). Filtering moved server-side because the client could only ever
+    /// filter the pages it had already loaded: with page 1 = 20 items out of a 1000-photo
+    /// event, selecting a tag showed a handful of tiles and looked complete. Matching is
+    /// now the exact `hashtag` row in both views, so the grid and the list can no longer
+    /// disagree about which photos carry a tag (the client matched a caption SUBSTRING, so
+    /// `#tanz` also matched `#tanzflaeche`).
+    pub hashtags: Option<String>,
+    /// Exact uploader display name, combined with the tag group using **AND**.
+    pub uploader: Option<String>,
+}
+
+/// Merge the single-tag and CSV tag params into one normalised, de-duplicated list.
+///
+/// Normalisation mirrors `Hashtag::upsert` exactly (trim, drop a leading `#`, lowercase), so
+/// a chip built from a display string like `#Tanz` matches the stored `tanz` row. Returns
+/// `None` when no usable tag was supplied, which makes the SQL predicate a no-op — an empty
+/// list must mean "no tag filter", never "match nothing".
+fn normalize_tags(single: Option<&str>, csv: Option<&str>) -> Option<Vec<String>> {
+    let mut out: Vec<String> = Vec::new();
+    let mut push = |raw: &str| {
+        let t = raw.trim().trim_start_matches('#').to_lowercase();
+        if !t.is_empty() && !out.contains(&t) {
+            out.push(t);
+        }
+    };
+    if let Some(s) = single {
+        push(s);
+    }
+    if let Some(s) = csv {
+        for part in s.split(',') {
+            push(part);
+        }
+    }
+    if out.is_empty() { None } else { Some(out) }
 }
 
 #[derive(Serialize)]
@@ -28,8 +61,8 @@ pub struct FeedUpload {
     pub uploader_name: String,
     pub preview_url: Option<String>,
     pub thumbnail_url: Option<String>,
-    /// Signed gateway URL for the full-resolution original. Always present.
-    pub original_url: Option<String>,
+    /// Big-screen (~2048px) variant for the diashow. Absent until the derivative exists.
+    pub display_url: Option<String>,
     pub mime_type: String,
     pub caption: Option<String>,
     pub like_count: i64,
@@ -51,6 +84,7 @@ struct FeedRow {
     uploader_name: String,
     preview_path: Option<String>,
     thumbnail_path: Option<String>,
+    display_path: Option<String>,
     mime_type: String,
     caption: Option<String>,
     like_count: i64,
@@ -58,120 +92,126 @@ struct FeedRow {
     created_at: DateTime<Utc>,
 }
 
-/// Build a feed DTO, minting fresh signed gateway URLs for each artifact. The
-/// preview/thumbnail URLs are present only when the derivative exists so the
-/// client can show a skeleton while compression is still running; the original
-/// URL is always present.
-fn to_feed_upload(r: FeedRow, liked: bool, secret: &str, now: i64) -> FeedUpload {
-    FeedUpload {
-        liked_by_me: liked,
-        preview_url: r
-            .preview_path
-            .as_ref()
-            .map(|_| media_token::signed_url(secret, "preview", r.id, now)),
-        thumbnail_url: r
-            .thumbnail_path
-            .as_ref()
-            .map(|_| media_token::signed_url(secret, "thumbnail", r.id, now)),
-        original_url: Some(media_token::signed_url(secret, "original", r.id, now)),
-        id: r.id,
-        user_id: r.user_id,
-        uploader_name: r.uploader_name,
-        mime_type: r.mime_type,
-        caption: r.caption,
-        like_count: r.like_count,
-        comment_count: r.comment_count,
-        created_at: r.created_at,
-    }
-}
-
 pub async fn feed(
     State(state): State<AppState>,
     auth: AuthUser,
-    headers: HeaderMap,
     Query(q): Query<FeedQuery>,
 ) -> Result<Json<FeedResponse>, AppError> {
-    let ip = client_ip(&headers, "unknown");
-    let rate_limits_on = config::get_bool(&state.pool, "rate_limits_enabled", true).await;
-    let feed_rate_on = config::get_bool(&state.pool, "feed_rate_enabled", true).await;
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let feed_rate_on = config::get_bool(&state.config_cache, "feed_rate_enabled", true).await;
     if rate_limits_on && feed_rate_on {
-        let rate_limit = config::get_usize(&state.pool, "feed_rate_per_min", 60).await;
-        if !state
-            .rate_limiter
-            .check(format!("feed:{ip}"), rate_limit, Duration::from_secs(60))
-        {
+        let rate_limit = config::get_usize(&state.config_cache, "feed_rate_per_min", 60).await;
+        // Keyed per-user, exactly like `feed_delta` below: at a venue every guest shares
+        // one public IP, so an IP key gave the whole party a single 60/min bucket and the
+        // fastest scroller starved everyone else.
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("feed:{}", auth.user_id),
+            rate_limit,
+            Duration::from_secs(60),
+        ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }
 
-    let limit = q.limit.unwrap_or(20).min(100);
+    // Clamped at BOTH ends: only the upper bound was enforced, so `?limit=-5` reached Postgres
+    // as `LIMIT -4` and answered a hand-written URL with a 500.
+    let limit = q.limit.unwrap_or(20).clamp(1, 100);
 
-    let rows = if let Some(hashtag) = &q.hashtag {
-        let tag = hashtag.trim().trim_start_matches('#').to_lowercase();
-        sqlx::query_as::<_, FeedRow>(
-            "SELECT v.id, v.user_id, v.uploader_name, v.preview_path, v.thumbnail_path,
-                    v.mime_type, v.caption, v.like_count, v.comment_count, v.created_at
-             FROM v_feed v
-             JOIN upload_hashtag uh ON uh.upload_id = v.id
-             JOIN hashtag h ON h.id = uh.hashtag_id AND h.tag = $1
-             WHERE v.event_id = $2
-               AND ($3::timestamptz IS NULL OR v.created_at < $3)
-             ORDER BY v.created_at DESC
-             LIMIT $4",
-        )
-        .bind(&tag)
-        .bind(auth.event_id)
-        .bind(
-            if let Some(cursor) = q.cursor {
-                get_cursor_time(&state.pool, cursor).await
-            } else {
-                None
-            },
-        )
-        .bind(limit + 1)
-        .fetch_all(&state.pool)
-        .await?
-    } else {
-        sqlx::query_as::<_, FeedRow>(
-            "SELECT id, user_id, uploader_name, preview_path, thumbnail_path,
-                    mime_type, caption, like_count, comment_count, created_at
-             FROM v_feed
-             WHERE event_id = $1
-               AND ($2::timestamptz IS NULL OR created_at < $2)
-             ORDER BY created_at DESC
-             LIMIT $3",
-        )
-        .bind(auth.event_id)
-        .bind(
-            if let Some(cursor) = q.cursor {
-                get_cursor_time(&state.pool, cursor).await
-            } else {
-                None
-            },
-        )
-        .bind(limit + 1)
-        .fetch_all(&state.pool)
-        .await?
+    // Resolve the cursor to a (created_at, id) position. The pair is compared as a
+    // tuple so ties on created_at break on id — keyset pagination on created_at
+    // alone would silently drop rows sharing a timestamp across a page boundary.
+    let (cursor_time, cursor_id) = match q.cursor {
+        Some(c) => match get_cursor_pos(&state.pool, c).await {
+            Some((t, id)) => (Some(t), Some(id)),
+            None => (None, None),
+        },
+        None => (None, None),
     };
 
+    // Tags from either param, normalised the same way `Hashtag::upsert` stores them
+    // (trimmed, leading `#` dropped, lowercased) so the comparison is exact.
+    let tags = normalize_tags(q.hashtag.as_deref(), q.hashtags.as_deref());
+    let uploader = q
+        .uploader
+        .as_deref()
+        .map(str::trim)
+        .filter(|s| !s.is_empty());
+
+    // ONE statement for every combination, rather than a branch per filter. `EXISTS` with
+    // `= ANY($4)` gives OR across the tag group without the row multiplication a JOIN would
+    // cause when a photo carries two selected tags; the uploader predicate ANDs on top. Both
+    // are no-ops when NULL, so the unfiltered feed takes the same path.
+    let rows = sqlx::query_as::<_, FeedRow>(
+        "SELECT v.id, v.user_id, v.uploader_name, v.preview_path, v.thumbnail_path,
+                v.display_path, v.mime_type, v.caption, v.like_count, v.comment_count,
+                v.created_at
+         FROM v_feed v
+         WHERE v.event_id = $1
+           AND ($2::timestamptz IS NULL OR (v.created_at, v.id) < ($2, $3))
+           AND ($4::text[] IS NULL OR EXISTS (
+                 SELECT 1 FROM upload_hashtag uh
+                 JOIN hashtag h ON h.id = uh.hashtag_id
+                 WHERE uh.upload_id = v.id AND h.tag = ANY($4)))
+           AND ($5::text IS NULL OR v.uploader_name = $5)
+         ORDER BY v.created_at DESC, v.id DESC
+         LIMIT $6",
+    )
+    .bind(auth.event_id)
+    .bind(cursor_time)
+    .bind(cursor_id)
+    .bind(tags.as_deref())
+    .bind(uploader)
+    .bind(limit + 1)
+    .fetch_all(&state.pool)
+    .await?;
+
     let has_more = rows.len() as i64 > limit;
     let rows: Vec<FeedRow> = rows.into_iter().take(limit as usize).collect();
-    let next_cursor = if has_more { rows.last().map(|r| r.id) } else { None };
+    let next_cursor = if has_more {
+        rows.last().map(|r| r.id)
+    } else {
+        None
+    };
 
     // Batch check which uploads the current user has liked
     let upload_ids: Vec<Uuid> = rows.iter().map(|r| r.id).collect();
     let liked_set = get_liked_set(&state.pool, auth.user_id, &upload_ids).await;
 
-    let now = Utc::now().timestamp();
-    let secret = &state.config.jwt_secret;
     let uploads = rows
         .into_iter()
         .map(|r| {
-            let liked = liked_set.contains(&r.id);
-            to_feed_upload(r, liked, secret, now)
+            // Gated media aliases (visibility-checked, direct /media blocked). Emit the
+            // URL only when the variant actually exists — the URL is what signals the
+            // client which variant to load.
+            let preview_url = r
+                .preview_path
+                .as_ref()
+                .map(|_| format!("/api/v1/upload/{}/preview", r.id));
+            let thumbnail_url = r
+                .thumbnail_path
+                .as_ref()
+                .map(|_| format!("/api/v1/upload/{}/thumbnail", r.id));
+            let display_url = r
+                .display_path
+                .as_ref()
+                .map(|_| format!("/api/v1/upload/{}/display", r.id));
+            FeedUpload {
+                liked_by_me: liked_set.contains(&r.id),
+                id: r.id,
+                user_id: r.user_id,
+                uploader_name: r.uploader_name,
+                preview_url,
+                thumbnail_url,
+                display_url,
+                mime_type: r.mime_type,
+                caption: r.caption,
+                like_count: r.like_count,
+                comment_count: r.comment_count,
+                created_at: r.created_at,
+            }
         })
         .collect();
 
@@ -190,90 +230,143 @@ pub struct DeltaQuery {
 pub struct DeltaResponse {
     pub uploads: Vec<FeedUpload>,
     pub deleted_ids: Vec<Uuid>,
-    /// Set when the delta was clamped (too-old cursor) or hit the row cap — the
-    /// client should do a full feed reload instead of trusting the partial set.
-    pub reload_required: bool,
+    /// Users whose uploads became hidden (banned / uploads_hidden) since `since`. A ban is
+    /// not a soft-delete, so it never appears in `deleted_ids`; without this, a client that
+    /// missed the ephemeral `user-hidden` SSE (a reconnecting projector, most acutely) would
+    /// keep displaying the banned user's already-loaded slides. The client evicts every
+    /// upload from these users on receipt.
+    pub hidden_user_ids: Vec<Uuid>,
+    /// True when the upload query hit `DELTA_LIMIT`: the response carries only the
+    /// newest slice of the gap, so the client must fall back to a full feed refresh
+    /// rather than merging (the older missed uploads are absent and unrecoverable
+    /// via a later delta, which advances `since` past them).
+    pub truncated: bool,
+    /// The server's clock at the moment this delta was computed. The client advances its
+    /// reconnect cursor from THIS, never `new Date()` — a browser clock even seconds fast
+    /// would otherwise silently skip uploads whose server `created_at` falls in the skew
+    /// window (they'd never reappear without a hard refresh).
+    pub server_time: DateTime<Utc>,
 }
 
-/// Hard cap on how many uploads one delta returns. Beyond this the client is
-/// told to reload rather than streaming the whole gallery through the view.
-const DELTA_LIMIT: i64 = 200;
-/// How far back a client-supplied `since` may reach. A tab backgrounded for days
-/// must not pull the entire event on reconnect.
-const DELTA_MAX_LOOKBACK_DAYS: i64 = 7;
-
 pub async fn feed_delta(
     State(state): State<AppState>,
     auth: AuthUser,
     Query(q): Query<DeltaQuery>,
 ) -> Result<Json<DeltaResponse>, AppError> {
-    // H7: feed_delta runs the (expensive) feed query and fires on every tab
-    // refocus, so it needs the same rate limit as feed(), keyed per user.
-    let rate_limits_on = config::get_bool(&state.pool, "rate_limits_enabled", true).await;
-    let feed_rate_on = config::get_bool(&state.pool, "feed_rate_enabled", true).await;
+    // Rate-limit the delta the same way as the paginated feed. Without this, ~100 clients
+    // reconnecting at once (post-outage, or a flapping network) each fire an unbounded
+    // delta fetch — a reconnect stampede. Keyed per-user so one client can't starve others
+    // behind a shared NAT.
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let feed_rate_on = config::get_bool(&state.config_cache, "feed_rate_enabled", true).await;
     if rate_limits_on && feed_rate_on {
-        let rate_limit = config::get_usize(&state.pool, "feed_rate_per_min", 60).await;
-        if !state.rate_limiter.check(
+        let rate_limit = config::get_usize(&state.config_cache, "feed_rate_per_min", 60).await;
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
             format!("feed_delta:{}", auth.user_id),
             rate_limit,
             Duration::from_secs(60),
         ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }
 
-    // Clamp the lookback server-side; signal a full reload if we had to.
-    let min_since = Utc::now() - chrono::Duration::days(DELTA_MAX_LOOKBACK_DAYS);
-    let clamped = q.since < min_since;
-    let since = if clamped { min_since } else { q.since };
+    // Anchor the next cursor to the DB clock, captured *before* the queries so an upload
+    // committed during this handler is re-fetched next time rather than skipped (a
+    // duplicate id merges idempotently on the client; a miss is unrecoverable).
+    let server_time: DateTime<Utc> = sqlx::query_scalar("SELECT NOW()")
+        .fetch_one(&state.pool)
+        .await?;
 
+    // Bounded like the paginated feed: a stale `since` could otherwise pull the
+    // entire event's uploads in one response. If a client hits the cap it should
+    // fall back to a full feed refresh rather than another delta.
+    const DELTA_LIMIT: i64 = 200;
+    // `>= since` (not `>`): `created_at` is not unique, so a strict `>` anchored to the exact
+    // timestamp of the last-seen upload silently drops a SECOND upload committed in the same
+    // microsecond — an unrecoverable live-update miss. `>=` re-includes the boundary rows;
+    // the client merges by id (see the feed-delta handler's `seen` set), so the duplicate is
+    // harmless while the tied upload is no longer lost. The cursor still advances to the
+    // response's `server_time`, so this doesn't re-fetch on every subsequent delta.
     let rows = sqlx::query_as::<_, FeedRow>(
         "SELECT id, user_id, uploader_name, preview_path, thumbnail_path,
-                mime_type, caption, like_count, comment_count, created_at
+                display_path, mime_type, caption, like_count, comment_count, created_at
          FROM v_feed
-         WHERE event_id = $1 AND created_at > $2
-         ORDER BY created_at DESC
+         WHERE event_id = $1 AND created_at >= $2
+         ORDER BY created_at DESC, id DESC
          LIMIT $3",
     )
     .bind(auth.event_id)
-    .bind(since)
-    .bind(DELTA_LIMIT + 1)
+    .bind(q.since)
+    .bind(DELTA_LIMIT)
     .fetch_all(&state.pool)
     .await?;
 
-    let capped = rows.len() as i64 > DELTA_LIMIT;
-    let rows: Vec<FeedRow> = rows.into_iter().take(DELTA_LIMIT as usize).collect();
-    let reload_required = clamped || capped;
+    // Hit the cap => this is only the newest slice of a larger gap. Signal the
+    // client to full-refresh instead of merging a partial delta.
+    let truncated = rows.len() as i64 >= DELTA_LIMIT;
 
+    // `>=` for the same tie-break reason as the uploads query above; re-signalling an
+    // already-removed id is idempotent on the client (it filters its list by these ids).
     let deleted_ids: Vec<(Uuid,)> = sqlx::query_as(
         "SELECT id FROM upload
-         WHERE event_id = $1 AND deleted_at IS NOT NULL AND deleted_at > $2",
+         WHERE event_id = $1 AND deleted_at IS NOT NULL AND deleted_at >= $2",
     )
     .bind(auth.event_id)
-    .bind(since)
+    .bind(q.since)
+    .fetch_all(&state.pool)
+    .await?;
+
+    // Users hidden since the cursor (ban / uploads_hidden). Uncapped like `deleted_ids` and
+    // for the same reason — an eviction the client misses is unrecoverable via a later delta.
+    let hidden_user_ids: Vec<(Uuid,)> = sqlx::query_as(
+        "SELECT id FROM \"user\"
+         WHERE event_id = $1 AND uploads_hidden = TRUE
+           AND uploads_hidden_at IS NOT NULL AND uploads_hidden_at >= $2",
+    )
+    .bind(auth.event_id)
+    .bind(q.since)
     .fetch_all(&state.pool)
     .await?;
 
     let upload_ids: Vec<Uuid> = rows.iter().map(|r| r.id).collect();
     let liked_set = get_liked_set(&state.pool, auth.user_id, &upload_ids).await;
 
-    let now = Utc::now().timestamp();
-    let secret = &state.config.jwt_secret;
     let uploads = rows
         .into_iter()
-        .map(|r| {
-            let liked = liked_set.contains(&r.id);
-            to_feed_upload(r, liked, secret, now)
+        .map(|r| FeedUpload {
+            liked_by_me: liked_set.contains(&r.id),
+            id: r.id,
+            user_id: r.user_id,
+            uploader_name: r.uploader_name,
+            preview_url: r
+                .preview_path
+                .as_ref()
+                .map(|_| format!("/api/v1/upload/{}/preview", r.id)),
+            thumbnail_url: r
+                .thumbnail_path
+                .as_ref()
+                .map(|_| format!("/api/v1/upload/{}/thumbnail", r.id)),
+            display_url: r
+                .display_path
+                .as_ref()
+                .map(|_| format!("/api/v1/upload/{}/display", r.id)),
+            mime_type: r.mime_type,
+            caption: r.caption,
+            like_count: r.like_count,
+            comment_count: r.comment_count,
+            created_at: r.created_at,
         })
         .collect();
 
     Ok(Json(DeltaResponse {
         uploads,
         deleted_ids: deleted_ids.into_iter().map(|r| r.0).collect(),
-        reload_required,
+        hidden_user_ids: hidden_user_ids.into_iter().map(|r| r.0).collect(),
+        truncated,
+        server_time,
     }))
 }
 
@@ -287,12 +380,11 @@ pub async fn hashtags(
     State(state): State<AppState>,
     auth: AuthUser,
 ) -> Result<Json<Vec<HashtagCount>>, AppError> {
-    let rows: Vec<(String, i64)> = sqlx::query_as(
-        "SELECT tag, upload_count FROM v_hashtag_counts WHERE event_id = $1",
-    )
-    .bind(auth.event_id)
-    .fetch_all(&state.pool)
-    .await?;
+    let rows: Vec<(String, i64)> =
+        sqlx::query_as("SELECT tag, upload_count FROM v_hashtag_counts WHERE event_id = $1")
+            .bind(auth.event_id)
+            .fetch_all(&state.pool)
+            .await?;
 
     Ok(Json(
         rows.into_iter()
@@ -301,14 +393,43 @@ pub async fn hashtags(
     ))
 }
 
-async fn get_cursor_time(pool: &sqlx::PgPool, cursor_id: Uuid) -> Option<DateTime<Utc>> {
-    let row: Option<(DateTime<Utc>,)> =
-        sqlx::query_as("SELECT created_at FROM upload WHERE id = $1")
+/// Every uploader who has at least one visible upload, for the grid's "Nutzer suchen" picker.
+///
+/// The picker used to derive names from the uploads currently in memory — page 1, 20 items —
+/// so typing a guest's name found nothing whenever their photos happened to sit below the
+/// fold, which reads as "search is broken". This is the authoritative list.
+///
+/// Reads `v_feed`, so it inherits exactly the feed's visibility rules: soft-deleted uploads,
+/// banned uploaders and hidden uploaders are all excluded, and a guest who has not uploaded
+/// anything never appears. Uncapped on purpose — one short string per uploader, bounded by
+/// the guest count, and truncating it would reintroduce the very bug this replaces.
+/// Deliberately NOT the host-only `/host/users` route: that one lists every joined guest and
+/// exposes moderation state.
+pub async fn uploaders(
+    State(state): State<AppState>,
+    auth: AuthUser,
+) -> Result<Json<Vec<String>>, AppError> {
+    let rows: Vec<(String,)> = sqlx::query_as(
+        "SELECT DISTINCT uploader_name FROM v_feed WHERE event_id = $1 ORDER BY uploader_name",
+    )
+    .bind(auth.event_id)
+    .fetch_all(&state.pool)
+    .await?;
+
+    Ok(Json(rows.into_iter().map(|(name,)| name).collect()))
+}
+
+/// Resolve a cursor id to its `(created_at, id)` position. Both are needed:
+/// `created_at` alone isn't unique, so pagination must break ties on `id` to
+/// avoid silently dropping rows that share a timestamp across a page boundary.
+async fn get_cursor_pos(pool: &sqlx::PgPool, cursor_id: Uuid) -> Option<(DateTime<Utc>, Uuid)> {
+    let row: Option<(DateTime<Utc>, Uuid)> =
+        sqlx::query_as("SELECT created_at, id FROM upload WHERE id = $1")
             .bind(cursor_id)
             .fetch_optional(pool)
             .await
             .ok()?;
-    row.map(|r| r.0)
+    row
 }
 
 async fn get_liked_set(
@@ -319,14 +440,51 @@ async fn get_liked_set(
     if upload_ids.is_empty() {
         return std::collections::HashSet::new();
     }
-    let rows: Vec<(Uuid,)> = sqlx::query_as(
-        "SELECT upload_id FROM \"like\" WHERE user_id = $1 AND upload_id = ANY($2)",
-    )
-    .bind(user_id)
-    .bind(upload_ids)
-    .fetch_all(pool)
-    .await
-    .unwrap_or_default();
+    let rows: Vec<(Uuid,)> =
+        sqlx::query_as("SELECT upload_id FROM \"like\" WHERE user_id = $1 AND upload_id = ANY($2)")
+            .bind(user_id)
+            .bind(upload_ids)
+            .fetch_all(pool)
+            .await
+            .unwrap_or_default();
 
     rows.into_iter().map(|r| r.0).collect()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::normalize_tags;
+
+    /// The chips carry display strings (`#Tanz`), the `hashtag` table stores `tanz`. If these
+    /// two drift the filter silently returns nothing, which is indistinguishable from "no
+    /// photos have this tag" — so pin the normalisation to `Hashtag::upsert`'s rule.
+    #[test]
+    fn tags_are_normalised_like_upsert_stores_them() {
+        assert_eq!(
+            normalize_tags(Some("#Tanz"), None),
+            Some(vec!["tanz".to_string()])
+        );
+        assert_eq!(
+            normalize_tags(None, Some(" #Buffet , reden ")),
+            Some(vec!["buffet".to_string(), "reden".to_string()])
+        );
+    }
+
+    /// An empty list must mean "no filter", never "match nothing" — returning `Some(vec![])`
+    /// would make `= ANY('{}')` false for every row and blank the feed.
+    #[test]
+    fn blank_input_disables_the_filter() {
+        assert_eq!(normalize_tags(None, None), None);
+        assert_eq!(normalize_tags(Some("   "), Some(" , ,#")), None);
+    }
+
+    /// Both params feed one list, de-duplicated: the list view sends `hashtag`, the grid sends
+    /// `hashtags`, and carrying a filter across views can legitimately set both to the same tag.
+    #[test]
+    fn single_and_csv_merge_without_duplicates() {
+        assert_eq!(
+            normalize_tags(Some("tanz"), Some("tanz,buffet")),
+            Some(vec!["tanz".to_string(), "buffet".to_string()])
+        );
+    }
+}

backend/src/handlers/host.rs

@@ -1,6 +1,6 @@
+use axum::Json;
 use axum::extract::{Path, State};
 use axum::http::StatusCode;
-use axum::Json;
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
@@ -12,18 +12,9 @@ use crate::models::event::Event;
 use crate::models::session::Session;
 use crate::models::upload::Upload;
 use crate::models::user::UserRole;
+use crate::services::export::Affects;
 use crate::state::{AppState, SseEvent};
 
-/// Revoke all of a user's sessions (best-effort). A failure here is logged but
-/// never fails the surrounding admin action — the live-role/ban reconciliation
-/// in `AuthUser` is the authoritative gate; revocation is defense-in-depth.
-async fn revoke_sessions(pool: &sqlx::PgPool, user_id: Uuid, action: &str) {
-    match Session::delete_by_user_id(pool, user_id).await {
-        Ok(n) => tracing::info!(target_user_id = %user_id, revoked = n, action, "sessions revoked"),
-        Err(e) => tracing::warn!(error = ?e, target_user_id = %user_id, action, "session revoke failed"),
-    }
-}
-
 // ── DTOs ─────────────────────────────────────────────────────────────────────
 
 #[derive(Serialize, sqlx::FromRow)]
@@ -44,11 +35,66 @@ pub struct EventStatus {
     pub is_active: bool,
     pub uploads_locked: bool,
     pub export_released: bool,
+    /// Free space on the volume the keepsake is written to. `None` when the mount can't be
+    /// resolved — the UI hides the widget rather than rendering a confident zero.
+    pub disk_free_bytes: Option<u64>,
+    /// What a full keepsake build would need right now (both halves).
+    pub keepsake_required_bytes: u64,
+    /// Whether the host should be warned. See [`disk_is_low`].
+    pub disk_low: bool,
 }
 
-#[derive(Deserialize)]
-pub struct BanRequest {
-    pub hide_uploads: bool,
+
+/// Is free space low enough that the host needs to know?
+///
+/// Two triggers, because a fixed threshold answers the wrong question. `postgres_data`,
+/// `media_data` and `exports_data` are all Docker named volumes on one filesystem, so a full disk
+/// does not degrade one subsystem — it stops Postgres writing and takes the event down. That is
+/// what the absolute floor is for.
+///
+/// The second trigger is the one that actually earns its place: the keepsake needs room for two
+/// gallery-sized archives, and the only moment a host can do anything about that is BEFORE they
+/// release. Warning at "you could not build the keepsake right now" turns a post-event dead end
+/// into a decision someone can still make.
+///
+/// IT MUST FIRE BEFORE THE UPLOAD GATE CLOSES, and that is why the reserve and the margin are
+/// here. The gate in `handlers::upload` refuses at `free < keepsake_required + DISK_RESERVE_BYTES`;
+/// warning at `free < keepsake_required` alone meant the two differed by the whole reserve, so
+/// the wall was always hit FIRST. Every guest would be blocked from uploading while this
+/// dashboard showed a comfortable disk and no banner at all — on the shipped 40 GB box, uploads
+/// stopping with ~27 GB free and nothing on screen to explain it, with no operator present.
+///
+/// The 25% margin makes it a warning rather than an obituary: the host sees it while there is
+/// still room to act (delete a few large videos, which refunds immediately and reopens the gate).
+fn disk_is_low(free: u64, keepsake_required: u64) -> bool {
+    let gate_closes_at = keepsake_required.saturating_add(crate::handlers::upload::DISK_RESERVE_BYTES as u64);
+    let warn_at = gate_closes_at.saturating_add(gate_closes_at / 4);
+    // No separate absolute-floor clause. There used to be `free < LOW_DISK_FLOOR_BYTES ||` here,
+    // and it was unreachable: `gate_closes_at` is at least DISK_RESERVE_BYTES, so `warn_at` is at
+    // least 1.25x it (12.5 GB) — always above the 10 GB floor. Two tests were named after that
+    // clause and neither could fail if it were deleted. Keeping dead code that tests claim to
+    // cover is worse than not having it.
+    free < warn_at
+}
+
+/// Count non-banned hosts/admins in the event OTHER than `excluding` — the operators
+/// who would remain if `excluding` were demoted or banned. Used to enforce the "an event
+/// always keeps at least one operator" floor.
+async fn remaining_operators(
+    state: &AppState,
+    event_id: Uuid,
+    excluding: Uuid,
+) -> Result<i64, AppError> {
+    let count = sqlx::query_scalar::<_, i64>(
+        "SELECT COUNT(*) FROM \"user\"
+         WHERE event_id = $1 AND id != $2
+           AND role IN ('host', 'admin') AND is_banned = FALSE",
+    )
+    .bind(event_id)
+    .bind(excluding)
+    .fetch_one(&state.pool)
+    .await?;
+    Ok(count)
 }
 
 #[derive(Deserialize)]
@@ -66,11 +112,29 @@ pub async fn get_event_status(
         .await?
         .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
 
+    // Measured on the EXPORT volume, not the media one: that is where the cliff is, and it is a
+    // distinct mount point even when both are backed by the same filesystem. The cached reading is
+    // right here — this is advisory, polled on every dashboard load, and a 15s-stale number costs
+    // nothing (unlike the export preflight, which reads uncached because it is about to write).
+    let free = state
+        .disk_cache
+        .snapshot(&state.config.export_path)
+        .map(|d| d.free);
+    let keepsake_required_bytes =
+        crate::services::export::keepsake_space_required(&state.pool, event.id)
+            .await
+            .unwrap_or(0);
+
     Ok(Json(EventStatus {
         name: event.name,
         is_active: event.is_active,
         uploads_locked: event.uploads_locked_at.is_some(),
         export_released: event.export_released_at.is_some(),
+        disk_free_bytes: free,
+        keepsake_required_bytes,
+        // Unknown free space is NOT low. Fails open, exactly as the upload quota and the export
+        // preflight do: a scary banner on an unreadable mount would train the host to ignore it.
+        disk_low: free.is_some_and(|f| disk_is_low(f, keepsake_required_bytes)),
     }))
 }
 
@@ -104,11 +168,13 @@ pub async fn ban_user(
     State(state): State<AppState>,
     RequireHost(auth): RequireHost,
     Path(user_id): Path<Uuid>,
-    Json(body): Json<BanRequest>,
 ) -> Result<StatusCode, AppError> {
+    // The ban request carries no body — ban always hides (no per-request options).
     // Cannot ban yourself or another host/admin
     if user_id == auth.user_id {
-        return Err(AppError::BadRequest("Du kannst dich nicht selbst sperren.".into()));
+        return Err(AppError::BadRequest(
+            "Du kannst dich nicht selbst sperren.".into(),
+        ));
     }
     let target = sqlx::query_as::<_, (String,)>(
         "SELECT role::text FROM \"user\" WHERE id = $1 AND event_id = $2",
@@ -119,23 +185,67 @@ pub async fn ban_user(
     .await?
     .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;
 
-    if target.0 == "admin" || (target.0 == "host" && auth.role != crate::models::user::UserRole::Admin) {
-        return Err(AppError::Forbidden("Du kannst diesen Benutzer nicht sperren.".into()));
+    if target.0 == "admin"
+        || (target.0 == "host" && auth.role != crate::models::user::UserRole::Admin)
+    {
+        return Err(AppError::Forbidden(
+            "Du kannst diesen Benutzer nicht sperren.".into(),
+        ));
     }
 
+    // Floor: never leave the event with zero operators. Banning removes the target from
+    // the active-operator pool, so refuse if they're the last non-banned host/admin.
+    if target.0 == "host" && remaining_operators(&state, auth.event_id, user_id).await? == 0 {
+        return Err(AppError::BadRequest(
+            "Der letzte Host kann nicht gesperrt werden.".into(),
+        ));
+    }
+
+    // Ban ALWAYS hides: a banned user's content is "gone" everywhere. The visibility
+    // views/queries now also filter on `is_banned` (defense in depth), and we set
+    // `uploads_hidden` so the existing `user-hidden` live-eviction path fires too. The old
+    // opt-out checkbox is gone — `hide_uploads` in the request is ignored.
+    //
+    // We deliberately do NOT revoke the banned user's sessions. This is a *read-only ban*
+    // by design (USER_JOURNEYS §10.3): the user keeps read access to the feed and can still
+    // download the released export — writes and host/admin actions are what the ban blocks
+    // (enforced live on the write handlers + Require{Host,Admin}). Revoking sessions would
+    // contradict that model, break the documented "banned guest can still download the
+    // keepsake" flow, and be ineffective anyway (the user could just /recover a new session).
+    //
+    // The ban and the keepsake invalidation are ONE transaction — see `host_delete_upload`.
+    let mut tx = state.pool.begin().await?;
     sqlx::query(
-        "UPDATE \"user\" SET is_banned = TRUE, uploads_hidden = $2 WHERE id = $1",
+        "UPDATE \"user\"
+         SET is_banned = TRUE, uploads_hidden = TRUE, uploads_hidden_at = NOW()
+         WHERE id = $1 AND event_id = $2",
     )
     .bind(user_id)
-    .bind(body.hide_uploads)
-    .execute(&state.pool)
+    .bind(auth.event_id)
+    .execute(&mut *tx)
     .await?;
 
-    revoke_sessions(&state.pool, user_id, "ban_user").await;
+    // A ban hides the user's uploads EVERYWHERE — and the keepsake is the place that matters most,
+    // because it is the copy people keep. The export already filters `is_banned = FALSE`, so a
+    // FUTURE export excludes them; without this, an ALREADY-RELEASED archive would keep serving a
+    // banned user's photos forever. Same class as a takedown, so same treatment.
+    let regen = crate::services::export::invalidate_and_arm(
+        &mut tx,
+        &state.config.event_slug,
+        Affects::Both,
+    )
+    .await?;
+    tx.commit().await?;
+    if let Some(r) = regen {
+        start_regen(&state, r);
+    }
 
-    // Tell the banned user's online devices to log out immediately.
+    // Evict their content live from every feed + the diashow so it disappears without
+    // each viewer having to reload. (Their own SSE stream is separately dropped by the
+    // is_banned revalidation in `sse::stream`, so they stop receiving live pushes while
+    // retaining plain read access.)
     let _ = state.sse_tx.send(SseEvent::new(
-        "user-banned",
+        "user-hidden",
         serde_json::json!({ "user_id": user_id }).to_string(),
     ));
 
@@ -143,7 +253,6 @@ pub async fn ban_user(
         actor_user_id = %auth.user_id,
         target_user_id = %user_id,
         event_id = %auth.event_id,
-        hide_uploads = body.hide_uploads,
         "host: ban_user"
     );
 
@@ -155,16 +264,56 @@ pub async fn unban_user(
     RequireHost(auth): RequireHost,
     Path(user_id): Path<Uuid>,
 ) -> Result<StatusCode, AppError> {
-    let result = sqlx::query(
-        "UPDATE \"user\" SET is_banned = FALSE WHERE id = $1 AND event_id = $2",
+    // Mirror the ban guard: a host may only lift bans on guests, never on hosts or
+    // admins. Without this a host could override an admin's ban of another host,
+    // which is asymmetric with `ban_user` and lets a host escalate a peer back in.
+    let target = sqlx::query_as::<_, (String,)>(
+        "SELECT role::text FROM \"user\" WHERE id = $1 AND event_id = $2",
     )
     .bind(user_id)
     .bind(auth.event_id)
-    .execute(&state.pool)
+    .fetch_optional(&state.pool)
+    .await?
+    .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;
+
+    if target.0 == "admin"
+        || (target.0 == "host" && auth.role != crate::models::user::UserRole::Admin)
+    {
+        return Err(AppError::Forbidden(
+            "Du kannst diesen Benutzer nicht entsperren.".into(),
+        ));
+    }
+
+    // Unban restores visibility too: ban set `uploads_hidden = TRUE`, so clearing only
+    // `is_banned` would leave their content invisible. Clear all three (the timestamp too,
+    // so a future ban stamps a fresh `uploads_hidden_at` the reconnect delta will replay).
+    let mut tx = state.pool.begin().await?;
+    let result = sqlx::query(
+        "UPDATE \"user\"
+         SET is_banned = FALSE, uploads_hidden = FALSE, uploads_hidden_at = NULL
+         WHERE id = $1 AND event_id = $2",
+    )
+    .bind(user_id)
+    .bind(auth.event_id)
+    .execute(&mut *tx)
     .await?;
     if result.rows_affected() == 0 {
         return Err(AppError::NotFound("Benutzer nicht gefunden.".into()));
     }
+
+    // The mirror of the ban case: an unban RESTORES their uploads to the export query, so an
+    // already-released keepsake is now missing content it should contain. Rebuild it.
+    let regen = crate::services::export::invalidate_and_arm(
+        &mut tx,
+        &state.config.event_slug,
+        Affects::Both,
+    )
+    .await?;
+    tx.commit().await?;
+    if let Some(r) = regen {
+        start_regen(&state, r);
+    }
+
     tracing::info!(
         actor_user_id = %auth.user_id,
         target_user_id = %user_id,
@@ -174,6 +323,55 @@ pub async fn unban_user(
     Ok(StatusCode::NO_CONTENT)
 }
 
+/// Force a keepsake rebuild. The ESCAPE HATCH.
+///
+/// Without this, a failed or stranded export is terminal at runtime: `release_gallery` refuses an
+/// already-released event ("bereits freigegeben"), `recover_exports` only runs at boot, and there is
+/// no other retry path — so the host's only options were restarting the container or reopening the
+/// event (which unlocks uploads to every guest and discards the release). This is also the recovery
+/// path for a keepsake that went stale for any reason we haven't thought of.
+pub async fn rebuild_export(
+    State(state): State<AppState>,
+    RequireHost(auth): RequireHost,
+) -> Result<StatusCode, AppError> {
+    let mut tx = state.pool.begin().await?;
+    let regen = crate::services::export::invalidate_and_arm(
+        &mut tx,
+        &state.config.event_slug,
+        Affects::Both,
+    )
+    .await?;
+    tx.commit().await?;
+
+    let Some(r) = regen else {
+        return Err(AppError::BadRequest(
+            "Die Galerie ist nicht freigegeben — es gibt nichts neu zu erzeugen.".into(),
+        ));
+    };
+
+    // No debounce: this is an explicit, deliberate host action, not a burst.
+    for export_type in ["zip", "html"] {
+        let _ = state.sse_tx.send(SseEvent::new(
+            "export-progress",
+            serde_json::json!({ "type": export_type, "progress_pct": 0 }).to_string(),
+        ));
+    }
+    crate::services::export::spawn_export_jobs(
+        r.event_id,
+        r.event_name,
+        r.epoch,
+        state.config.comments_enabled,
+        std::time::Duration::ZERO,
+        state.pool.clone(),
+        state.config.media_path.clone(),
+        state.config.export_path.clone(),
+        state.sse_tx.clone(),
+    );
+
+    tracing::info!(actor_user_id = %auth.user_id, "host: rebuild_export");
+    Ok(StatusCode::NO_CONTENT)
+}
+
 pub async fn set_role(
     State(state): State<AppState>,
     RequireHost(auth): RequireHost,
@@ -191,14 +389,15 @@ pub async fn set_role(
         _ => {
             return Err(AppError::BadRequest(
                 "Ungültige Rolle. Erlaubt: guest, host.".into(),
-            ))
+            ));
         }
     };
 
-    // Look up the current role so we can apply the host-vs-admin guard. Hosts may
-    // promote guests and demote *other* hosts (the user explicitly requested this
-    // expansion). Hosts may not touch admins. Admins may do anything (except change
-    // themselves, blocked above).
+    // Look up the current role so we can apply the host-vs-admin guard. A plain host may
+    // promote/demote GUESTS only; it may not change any host's or admin's role (see the
+    // guard below — this closes the demote-a-peer-host→ban/PIN-reset takeover chain, F1).
+    // Only an admin may change a host's role. Admins may do anything except change
+    // themselves (blocked above).
     let target = sqlx::query_as::<_, (String,)>(
         "SELECT role::text FROM \"user\" WHERE id = $1 AND event_id = $2",
     )
@@ -208,9 +407,25 @@ pub async fn set_role(
     .await?
     .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;
 
-    if target.0 == "admin" {
+    // Admins are untouchable by hosts. A plain host also may not demote another
+    // *host*: without this guard a host could demote a peer host to guest and then
+    // ban / PIN-reset (→ account-takeover via /recover) them — the ban/pin-reset peer
+    // guards key off the target's *current* role, so a prior demotion would launder
+    // past them. Only an admin may change a host's role.
+    if target.0 == "admin" || (target.0 == "host" && auth.role != UserRole::Admin) {
         return Err(AppError::Forbidden(
-            "Admins können nicht geändert werden.".into(),
+            "Du darfst die Rolle dieses Benutzers nicht ändern.".into(),
+        ));
+    }
+
+    // Floor: demoting the last non-banned host/admin to guest would leave the event with
+    // no operator. Refuse.
+    if new_role == "guest"
+        && target.0 == "host"
+        && remaining_operators(&state, auth.event_id, user_id).await? == 0
+    {
+        return Err(AppError::BadRequest(
+            "Der letzte Host kann nicht zum Gast gemacht werden.".into(),
         ));
     }
 
@@ -220,13 +435,6 @@ pub async fn set_role(
         .bind(auth.event_id)
         .execute(&state.pool)
         .await?;
-
-    // Force a clean re-auth so the new role can't be cached client-side and so
-    // any in-flight tokens carrying the old role are invalidated. The live-role
-    // reconciliation in AuthUser already prevents privilege escalation, but
-    // revoking is cheaper to reason about.
-    revoke_sessions(&state.pool, user_id, "set_role").await;
-
     tracing::info!(
         actor_user_id = %auth.user_id,
         target_user_id = %user_id,
@@ -278,28 +486,40 @@ pub async fn reset_user_pin(
         _ => {
             return Err(AppError::Forbidden(
                 "Du darfst die PIN dieses Benutzers nicht zurücksetzen.".into(),
-            ))
+            ));
         }
     }
 
-    let pin: String = format!("{:06}", rand::rng().random_range(0..1_000_000u32));
-    let pin_hash = crate::services::password::hash(pin.clone(), 12).await?;
+    let pin: String = format!("{:04}", rand::rng().random_range(0..10000u32));
+    let pin_hash = crate::auth::handlers::hash_password(pin.clone(), 12).await?;
 
     sqlx::query(
         "UPDATE \"user\"
          SET recovery_pin_hash = $1,
              failed_pin_attempts = 0,
              pin_locked_until = NULL
-         WHERE id = $2",
+         WHERE id = $2 AND event_id = $3",
     )
     .bind(&pin_hash)
     .bind(user_id)
+    .bind(auth.event_id)
     .execute(&state.pool)
     .await?;
 
-    // A PIN reset must invalidate existing sessions so a compromised/old token
-    // can't outlive the reset.
-    revoke_sessions(&state.pool, user_id, "reset_user_pin").await;
+    // A PIN reset means the old credential is compromised/forgotten — revoke every
+    // existing session so old devices must re-authenticate with the new PIN. This is a
+    // security-relevant revoke: if it fails, the old sessions stay valid (sessions are
+    // token- not PIN-bound), so surface the error in logs rather than swallowing it
+    // silently while reporting success to the host.
+    if let Err(e) = Session::delete_all_for_user(&state.pool, user_id).await {
+        tracing::error!(error = ?e, user_id = %user_id, "PIN reset: failed to revoke sessions");
+    }
+
+    // Resolve any pending in-app "I forgot my PIN" request for this user.
+    let _ = sqlx::query("DELETE FROM pin_reset_request WHERE user_id = $1")
+        .bind(user_id)
+        .execute(&state.pool)
+        .await;
 
     // Notify the *recipient* device(s) if they happen to be online so they can clear
     // their cached local PIN. They'll save the new one on the next /recover.
@@ -318,26 +538,125 @@ pub async fn reset_user_pin(
     Ok(Json(PinResetResponse { pin }))
 }
 
+#[derive(Serialize, sqlx::FromRow)]
+pub struct PinResetRequestSummary {
+    pub id: Uuid,
+    pub user_id: Uuid,
+    pub display_name: String,
+    pub created_at: DateTime<Utc>,
+}
+
+/// List pending in-app PIN-reset requests so a host can action them (via the existing
+/// `reset_user_pin`, which also clears the request).
+pub async fn list_pin_reset_requests(
+    State(state): State<AppState>,
+    RequireHost(auth): RequireHost,
+) -> Result<Json<Vec<PinResetRequestSummary>>, AppError> {
+    let rows = sqlx::query_as::<_, PinResetRequestSummary>(
+        "SELECT r.id, r.user_id, u.display_name, r.created_at
+         FROM pin_reset_request r
+         JOIN \"user\" u ON u.id = r.user_id
+         WHERE r.event_id = $1
+         ORDER BY r.created_at ASC",
+    )
+    .bind(auth.event_id)
+    .fetch_all(&state.pool)
+    .await?;
+    Ok(Json(rows))
+}
+
+/// Dismiss a PIN-reset request without resetting (e.g. the host couldn't verify the
+/// requester's identity).
+pub async fn dismiss_pin_reset_request(
+    State(state): State<AppState>,
+    RequireHost(auth): RequireHost,
+    Path(id): Path<Uuid>,
+) -> Result<StatusCode, AppError> {
+    sqlx::query("DELETE FROM pin_reset_request WHERE id = $1 AND event_id = $2")
+        .bind(id)
+        .bind(auth.event_id)
+        .execute(&state.pool)
+        .await?;
+    Ok(StatusCode::NO_CONTENT)
+}
+
+/// Content changed AFTER the gallery was released — regenerate the keepsake.
+///
+/// Deleting a photo used to remove it from the live feed but leave it in the already-generated
+/// archive FOREVER: the old `if ready { continue }` skip guaranteed the export was never rebuilt.
+/// For a takedown ("please remove my photo") that is the one place it most needs to disappear.
+///
+/// Bumping the epoch (while staying released) retires the current generation, so the stale archive
+/// stops being downloadable the instant the delete commits, and a fresh worker rebuilds it without
+/// the removed content. The download 404s in the meantime, which is the correct answer — serving
+/// the old archive would serve the deleted photo.
+/// Start the workers for a regeneration that was armed inside a (now-committed) transaction, and
+/// tell every client the current keepsake just became undownloadable.
+///
+/// The SSE matters: bumping the epoch retires the archive INSTANTLY, so `/export/zip` starts 404ing
+/// the moment the change commits. Without a nudge, a guest sitting on `/export` keeps rendering an
+/// enabled "download" button for the whole rebuild. Both the nav badge and the export page already
+/// refetch `/export/status` on `export-progress`, so a 0% tick is the cheapest correct signal.
+pub fn start_regen(state: &AppState, regen: crate::services::export::PendingRegen) {
+    for export_type in ["zip", "html"] {
+        let _ = state.sse_tx.send(SseEvent::new(
+            "export-progress",
+            serde_json::json!({ "type": export_type, "progress_pct": 0 }).to_string(),
+        ));
+    }
+    crate::services::export::spawn_export_jobs(
+        regen.event_id,
+        regen.event_name,
+        regen.epoch,
+        state.config.comments_enabled,
+        // Debounced: a takedown pass is a burst, and each request retires the last generation. The
+        // delay lets superseded workers fail their claim and do zero work instead of each building
+        // a full archive. See export::REGEN_DEBOUNCE.
+        crate::services::export::REGEN_DEBOUNCE,
+        state.pool.clone(),
+        state.config.media_path.clone(),
+        state.config.export_path.clone(),
+        state.sse_tx.clone(),
+    );
+}
+
 pub async fn host_delete_upload(
     State(state): State<AppState>,
     RequireHost(auth): RequireHost,
     Path(upload_id): Path<Uuid>,
 ) -> Result<StatusCode, AppError> {
-    let paths = Upload::soft_delete_in_event(&state.pool, upload_id, auth.event_id)
+    let upload = Upload::find_by_id_and_event(&state.pool, upload_id, auth.event_id)
         .await?
         .ok_or_else(|| AppError::NotFound("Upload nicht gefunden.".into()))?;
 
-    crate::services::media_fs::unlink_media(&state.config.media_path, &paths).await;
+    // The delete and the keepsake invalidation are ONE transaction: if the delete committed and the
+    // invalidation didn't, the taken-down photo would stay downloadable forever and nothing would
+    // notice (the keepsake still looks complete, and the host can no longer find the upload to retry).
+    let mut tx = state.pool.begin().await?;
+    let deleted = Upload::soft_delete_in_event(&mut tx, upload_id, auth.event_id).await?;
+    if !deleted {
+        return Err(AppError::NotFound("Upload nicht gefunden.".into()));
+    }
+    let regen = crate::services::export::invalidate_and_arm(
+        &mut tx,
+        &state.config.event_slug,
+        Affects::Both,
+    )
+    .await?;
+    tx.commit().await?;
 
     let _ = state.sse_tx.send(SseEvent::new(
         "upload-deleted",
-        serde_json::json!({ "upload_id": upload_id }).to_string(),
+        serde_json::json!({ "upload_id": upload.id }).to_string(),
     ));
+    if let Some(r) = regen {
+        start_regen(&state, r);
+    }
 
     tracing::info!(
         actor_user_id = %auth.user_id,
         event_id = %auth.event_id,
-        upload_id = %upload_id,
+        upload_id = %upload.id,
         "host: host_delete_upload"
     );
 
@@ -349,11 +668,29 @@ pub async fn host_delete_comment(
     RequireHost(auth): RequireHost,
     Path(comment_id): Path<Uuid>,
 ) -> Result<StatusCode, AppError> {
-    let deleted =
-        Comment::soft_delete_in_event(&state.pool, comment_id, auth.event_id).await?;
+    let mut tx = state.pool.begin().await?;
+    let deleted = Comment::soft_delete_in_event(&mut tx, comment_id, auth.event_id).await?;
     if !deleted {
         return Err(AppError::NotFound("Kommentar nicht gefunden.".into()));
     }
+    // Only the HTML viewer embeds comments — the ZIP is media-only, so it is carried forward rather
+    // than rebuilt. Otherwise moderating one comment would 404 the photo download for minutes to
+    // change nothing in it.
+    let regen = crate::services::export::invalidate_and_arm(
+        &mut tx,
+        &state.config.event_slug,
+        Affects::ViewerOnly,
+    )
+    .await?;
+    tx.commit().await?;
+
+    let _ = state.sse_tx.send(SseEvent::new(
+        "comment-deleted",
+        serde_json::json!({ "comment_id": comment_id }).to_string(),
+    ));
+    if let Some(r) = regen {
+        start_regen(&state, r);
+    }
     tracing::info!(
         actor_user_id = %auth.user_id,
         event_id = %auth.event_id,
@@ -367,14 +704,18 @@ pub async fn close_event(
     State(state): State<AppState>,
     RequireHost(_auth): RequireHost,
 ) -> Result<StatusCode, AppError> {
-    sqlx::query(
+    let result = sqlx::query(
         "UPDATE event SET uploads_locked_at = NOW() WHERE slug = $1 AND uploads_locked_at IS NULL",
     )
     .bind(&state.config.event_slug)
     .execute(&state.pool)
     .await?;
 
-    let _ = state.sse_tx.send(SseEvent::new("event-closed", "{}"));
+    // Only broadcast when this call actually flipped the lock — closing an
+    // already-closed event is a no-op and shouldn't spam listeners.
+    if result.rows_affected() > 0 {
+        let _ = state.sse_tx.send(SseEvent::new("event-closed", "{}"));
+    }
 
     Ok(StatusCode::NO_CONTENT)
 }
@@ -383,14 +724,29 @@ pub async fn open_event(
     State(state): State<AppState>,
     RequireHost(_auth): RequireHost,
 ) -> Result<StatusCode, AppError> {
-    sqlx::query(
-        "UPDATE event SET uploads_locked_at = NULL WHERE slug = $1",
+    // Reopening invalidates any prior release: the keepsake was snapshotted at release time, so
+    // allowing new uploads afterwards would silently diverge the live feed from the frozen export.
+    //
+    // ONE statement retires the entire export generation. Bumping `export_epoch` in the same write
+    // that clears `export_released_at` instantly invalidates every in-flight worker, every `done`
+    // row and all readiness — because readiness is DERIVED from this epoch (migration 014), not
+    // stored. There is no export_job row to touch and nothing to keep in sync, so this needs no
+    // transaction. Any worker still streaming holds the old epoch and is now inert: its
+    // epoch-guarded finalize matches nothing, and it discards its own output.
+    let result = sqlx::query(
+        "UPDATE event
+         SET uploads_locked_at  = NULL,
+             export_released_at = NULL,
+             export_epoch       = export_epoch + 1
+         WHERE slug = $1 AND (uploads_locked_at IS NOT NULL OR export_released_at IS NOT NULL)",
     )
     .bind(&state.config.event_slug)
     .execute(&state.pool)
     .await?;
 
-    let _ = state.sse_tx.send(SseEvent::new("event-opened", "{}"));
+    if result.rows_affected() > 0 {
+        let _ = state.sse_tx.send(SseEvent::new("event-opened", "{}"));
+    }
 
     Ok(StatusCode::NO_CONTENT)
 }
@@ -399,76 +755,167 @@ pub async fn release_gallery(
     State(state): State<AppState>,
     RequireHost(_auth): RequireHost,
 ) -> Result<StatusCode, AppError> {
-    let event = Event::find_by_slug(&state.pool, &state.config.event_slug)
-        .await?
-        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
-
-    // Atomically claim the release AND enqueue the jobs in one transaction (M8).
-    // The claim UPDATE row-locks the event row and the lock is held until commit
-    // — *after* the export_job rows exist — so a second concurrent press re-reads
-    // the now-present jobs and matches 0 rows (clean 400). Doing the UPDATE and
-    // INSERTs as separate autocommit statements left a cross-table TOCTOU window
-    // where both presses could win and race the same output files.
+    // The release claim, the epoch bump, the upload lock and BOTH job rows are written in ONE
+    // transaction. Two reasons, both of which were live bugs:
     //
-    // Re-release guard (M8-3): allow when never released, OR nothing is currently
-    // in progress and at least one job terminally failed. The old "every job
-    // failed" guard left a one-sided failure (zip done, html failed) permanently
-    // unrecoverable.
+    //  1. Cancellation. This handler used to commit `export_released_at` and only THEN await the
+    //     enqueue. Axum drops the handler future when the client disconnects (closed tab, proxy
+    //     timeout), which left the event released and uploads locked with ZERO export_job rows and
+    //     no workers: downloads 404 forever and the host cannot retry, because release_gallery
+    //     rejects an already-released event ("bereits freigegeben"). Only a restart escaped it.
+    //     Now nothing is committed until every row is written, and the workers are spawned AFTER
+    //     the commit (a detached `tokio::spawn` survives cancellation).
+    //  2. Atomicity vs. a concurrent reopen. Bumping the epoch in the same statement that sets
+    //     `export_released_at` means no worker and no reader can ever observe "released again but
+    //     the generation hasn't moved on yet" — the window every previous fix kept leaving open.
+    //
+    // Release also locks uploads in the same statement (release ⇒ lock), so the export snapshot is
+    // taken against a frozen upload set. `COALESCE` preserves an earlier explicit lock time.
     let mut tx = state.pool.begin().await?;
 
-    let claim = sqlx::query(
-        "UPDATE event SET export_released_at = NOW()
-         WHERE slug = $1
-           AND (
-             export_released_at IS NULL
-             OR (
-               NOT EXISTS (
-                 SELECT 1 FROM export_job j
-                 WHERE j.event_id = event.id AND j.status IN ('running', 'pending')
-               )
-               AND EXISTS (
-                 SELECT 1 FROM export_job j
-                 WHERE j.event_id = event.id AND j.status = 'failed'
-               )
-             )
-           )",
+    let claimed: Option<(Uuid, String, i64)> = sqlx::query_as(
+        "UPDATE event
+         SET export_released_at = NOW(),
+             uploads_locked_at  = COALESCE(uploads_locked_at, NOW()),
+             export_epoch       = export_epoch + 1
+         WHERE slug = $1 AND export_released_at IS NULL
+         RETURNING id, name, export_epoch",
     )
     .bind(&state.config.event_slug)
-    .execute(&mut *tx)
+    .fetch_optional(&mut *tx)
     .await?;
 
-    if claim.rows_affected() == 0 {
-        tx.rollback().await.ok();
-        return Err(AppError::BadRequest(
-            "Galerie wurde bereits freigegeben.".into(),
-        ));
-    }
+    let Some((event_id, event_name, epoch)) = claimed else {
+        // Distinguish "no such event" from "already released" for a clean error.
+        let exists = Event::find_by_slug(&state.pool, &state.config.event_slug)
+            .await?
+            .is_some();
+        return Err(if exists {
+            AppError::BadRequest("Galerie wurde bereits freigegeben.".into())
+        } else {
+            AppError::NotFound("Event nicht gefunden.".into())
+        });
+    };
 
-    // Enqueue export jobs, resetting any prior terminal rows so the workers
-    // re-run cleanly (including an already-`done` sibling on re-release).
-    for export_type in ["zip", "html"] {
-        sqlx::query(
-            "INSERT INTO export_job (event_id, type) VALUES ($1, $2::export_type)
-             ON CONFLICT (event_id, type)
-             DO UPDATE SET status = 'pending', progress_pct = 0,
-                           error_message = NULL, completed_at = NULL",
-        )
-        .bind(event.id)
-        .bind(export_type)
-        .execute(&mut *tx)
-        .await?;
-    }
+    // Arm both types at THIS epoch. No "skip the type that's already ready" check any more: the
+    // epoch bump above retired every prior generation, so there is nothing to preserve and nothing
+    // to be fooled by. (That skip was how a stale ready flag used to suppress regeneration.)
+    crate::services::export::enqueue_jobs_at_epoch(&mut tx, event_id, epoch).await?;
 
     tx.commit().await?;
 
-    // Spawn export workers only after the claim+enqueue is durably committed.
+    // Release locks uploads too — tell any open composer to flip to the locked UI live rather than
+    // discovering it via a rejected upload.
+    let _ = state.sse_tx.send(SseEvent::new("event-closed", "{}"));
+
+    // Detached — survives this handler being cancelled.
     crate::services::export::spawn_export_jobs(
-        event.id,
-        event.name,
+        event_id,
+        event_name,
+        epoch,
+        state.config.comments_enabled,
+        std::time::Duration::ZERO,
         state.pool.clone(),
         state.config.media_path.clone(),
+        state.config.export_path.clone(),
         state.sse_tx.clone(),
     );
 
     Ok(StatusCode::NO_CONTENT)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::disk_is_low;
+    use crate::handlers::upload::DISK_RESERVE_BYTES;
+    use crate::services::export::required_free_bytes;
+
+    const GB: u64 = 1_000_000_000;
+
+    #[test]
+    fn a_healthy_disk_with_room_for_the_keepsake_is_not_low() {
+        // Room for the keepsake AND the reserve the upload gate holds back, with margin.
+        assert!(!disk_is_low(60 * GB, 25 * GB));
+    }
+
+    /// Renamed from `the_absolute_floor_fires_...`: there is no separate floor clause any more
+    /// (see `disk_is_low`). What still has to hold is the behaviour the floor was there FOR — a
+    /// nearly-empty disk is low even when the gallery is small enough that the keepsake term
+    /// alone would clear it, because all three volumes share one filesystem and Postgres needs
+    /// room to write.
+    #[test]
+    fn a_nearly_empty_disk_is_low_even_when_the_gallery_is_tiny() {
+        // All three volumes share one filesystem, so running out doesn't degrade one subsystem —
+        // Postgres stops being able to write and the event goes down. A 1 GB gallery would clear
+        // the keepsake test comfortably; the floor is what catches this.
+        assert!(disk_is_low(5 * GB, GB));
+        assert!(disk_is_low(9 * GB, 0));
+        assert!(!disk_is_low(20 * GB, 0), "a roomy empty disk is not low");
+    }
+
+    /// THE PROPERTY THIS EXISTS FOR: the host must be warned BEFORE guests are blocked.
+    ///
+    /// `handlers::upload` refuses at `free < keepsake_required + DISK_RESERVE_BYTES`. If the
+    /// banner fires only at or below that, the host's first signal is 100 guests being unable
+    /// to upload while the dashboard shows a comfortable disk — with nobody on site to ask.
+    #[test]
+    fn the_banner_always_fires_before_the_upload_gate_closes() {
+        // Asserting `disk_is_low(gate_closes_at, required)` is what this used to do, and it was a
+        // tautology: `disk_is_low` recomputes the same `gate_closes_at` internally and compares
+        // against `gate + gate/4`, so the assertion reduced to `G < G + G/4` — true for every G,
+        // for any margin, even a margin of zero. It could not detect the banner being moved to
+        // exactly the gate, which is the regression it is named for.
+        //
+        // So pin the GAP instead: find the free-space level at which the banner starts, and
+        // require it to be strictly above the level at which the gate closes, by a usable amount.
+        for media_gb in [0u64, 1, 4, 8, 16, 32] {
+            let required = required_free_bytes(media_gb * GB, 2);
+            let gate_closes_at = required + DISK_RESERVE_BYTES as u64;
+
+            // Just above the gate: guests can still upload, and the host must already be warned.
+            assert!(
+                disk_is_low(gate_closes_at + 1, required),
+                "at media={media_gb}GB the banner is not yet showing while the gate still allows uploads"
+            );
+
+            // The warning must lead by a margin the host can act inside, not by one byte.
+            let mut warn_starts_at = gate_closes_at;
+            while disk_is_low(warn_starts_at, required) {
+                warn_starts_at += GB / 10;
+            }
+            assert!(
+                warn_starts_at >= gate_closes_at + gate_closes_at / 5,
+                "at media={media_gb}GB the banner leads the gate by only                  {} bytes",
+                warn_starts_at - gate_closes_at
+            );
+        }
+    }
+
+    #[test]
+    fn plenty_of_space_is_still_low_when_the_keepsake_would_not_fit() {
+        // THE case the fixed threshold misses, and the one that matters: 30 GB free is nowhere near
+        // any floor, but a 30 GB gallery needs room for TWO archives. The host can act on this
+        // before releasing; after releasing, they cannot.
+        assert!(disk_is_low(30 * GB, 66 * GB));
+    }
+
+    #[test]
+    fn the_keepsake_trigger_is_exact_at_the_boundary() {
+        // The boundary is the UPLOAD GATE's threshold plus a 25% margin, not the bare keepsake
+        // size — see `disk_is_low`. Warning at the bare size fired only after the gate had
+        // already blocked every guest.
+        let required = 20 * GB;
+        let gate = required + DISK_RESERVE_BYTES as u64;
+        let warn_at = gate + gate / 4;
+        assert!(!disk_is_low(warn_at, required), "exactly enough is enough");
+        assert!(disk_is_low(warn_at - 1, required));
+    }
+
+    #[test]
+    fn an_empty_gallery_still_reserves_room_for_postgres() {
+        // With no gallery the keepsake term is 0, so the warn threshold collapses to
+        // 1.25 x DISK_RESERVE_BYTES (12.5 GB), which dominates the 10 GB absolute floor.
+        assert!(!disk_is_low(13 * GB, 0));
+        assert!(disk_is_low(9 * GB, 0));
+    }
+}

backend/src/handlers/me.rs

@@ -7,14 +7,14 @@
 //!   account page loads this once on mount instead of issuing several round trips.
 //! - `GET /api/v1/me/quota`  — live per-user storage quota estimate.
 
-use axum::extract::State;
 use axum::Json;
+use axum::extract::State;
 use serde::Serialize;
 
 use crate::auth::middleware::AuthUser;
 use crate::error::AppError;
 use crate::handlers::upload::compute_storage_quota;
-use crate::models::user::User;
+use crate::models::user::{User, UserRole};
 use crate::services::config;
 use crate::state::AppState;
 
@@ -37,12 +37,26 @@ pub async fn get_quota(
 
     let estimate = compute_storage_quota(&state).await;
 
+    // Raw server telemetry (free disk, concurrent uploader count) is staff-only — it
+    // must never reach a guest, even though the guest upload UI no longer renders it.
+    // A guest still gets their own `used`/`limit` so enforcement stays transparent to
+    // the code paths that consume it; only the server-wide fields are zeroed.
+    let is_staff = matches!(auth.role, UserRole::Host | UserRole::Admin);
+
     Ok(Json(QuotaDto {
         enabled: estimate.limit_bytes.is_some(),
         used_bytes: user.total_upload_bytes,
         limit_bytes: estimate.limit_bytes,
-        active_uploaders: estimate.active_uploaders,
-        free_disk_bytes: estimate.free_disk_bytes,
+        active_uploaders: if is_staff {
+            estimate.active_uploaders
+        } else {
+            0
+        },
+        free_disk_bytes: if is_staff {
+            estimate.free_disk_bytes
+        } else {
+            0
+        },
     }))
 }
 
@@ -55,9 +69,20 @@ pub struct MeContextDto {
     pub privacy_note: String,
     pub quota_enabled: bool,
     pub storage_quota_enabled: bool,
-    /// Whether uploads are currently locked for the event, so the client can show
-    /// a banner + disable the upload affordance on load (not just via SSE).
+    /// Uploads are locked (event closed) — the composer should show a locked state live
+    /// instead of letting a guest compose an upload only to eat a 403.
     pub uploads_locked: bool,
+    /// The gallery has been released and the export snapshotted — uploads are permanently
+    /// closed for this run (release ⇒ lock, and reopening regenerates).
+    pub gallery_released: bool,
+    /// This guest is banned: a deliberately READ-ONLY ban (see `handlers/host.rs`) — they keep
+    /// the feed and the keepsake, but every write is refused.
+    ///
+    /// Exposed so the UI can SAY so. Without it the client had no idea, so the upload button,
+    /// the like button and "Löschen" all rendered enabled and returned 403 "Du bist gesperrt."
+    /// on every tap — a guest tapping upload repeatedly with nobody to ask. The lock case
+    /// (`uploads_locked`) has always been surfaced for exactly this reason; a ban was not.
+    pub is_banned: bool,
 }
 
 pub async fn get_context(
@@ -68,13 +93,21 @@ pub async fn get_context(
         .await?
         .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;
 
-    let privacy_note = config::get_str(&state.pool, "privacy_note", "").await;
-    let quota_enabled = config::get_bool(&state.pool, "quota_enabled", true).await;
-    let storage_quota_enabled = config::get_bool(&state.pool, "storage_quota_enabled", true).await;
-    let uploads_locked = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
-        .await?
+    let privacy_note = config::get_str(&state.config_cache, "privacy_note", "").await;
+    let quota_enabled = config::get_bool(&state.config_cache, "quota_enabled", true).await;
+    let storage_quota_enabled =
+        config::get_bool(&state.config_cache, "storage_quota_enabled", true).await;
+
+    let event =
+        crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug).await?;
+    let uploads_locked = event
+        .as_ref()
         .map(|e| e.uploads_locked_at.is_some())
         .unwrap_or(false);
+    let gallery_released = event
+        .as_ref()
+        .map(|e| e.export_released_at.is_some())
+        .unwrap_or(false);
 
     Ok(Json(MeContextDto {
         user_id: user.id,
@@ -84,5 +117,7 @@ pub async fn get_context(
         quota_enabled,
         storage_quota_enabled,
         uploads_locked,
+        gallery_released,
+        is_banned: user.is_banned,
     }))
 }

backend/src/handlers/media.rs

@@ -1,117 +0,0 @@
-//! Authenticated media gateway.
-//!
-//! Replaces the raw `/media` `ServeDir`. Every media byte now flows through a
-//! signature check plus a DB lookup, so:
-//!   - soft-deleted uploads 404 (`find_by_id` filters `deleted_at`) — closes C3,
-//!   - ban-hidden uploaders' artifacts 404 (mirrors the `v_feed` rule) — H2,
-//!   - the export archives (which have no `upload` row) are unreachable — C1,
-//!   - HTML/SVG can't be served as an active document — the response carries
-//!     `nosniff` + a locked-down CSP (defense-in-depth behind the upload-time
-//!     allowlist) — C2 sink.
-//!
-//! Access is authorized by the embedded HMAC signature (see `media_token`), not
-//! a Bearer header, because `<img>`/`<video>` cannot send one.
-
-use axum::extract::{Path, Query, State};
-use axum::response::Response;
-use chrono::Utc;
-use serde::Deserialize;
-use uuid::Uuid;
-
-use crate::error::AppError;
-use crate::models::upload::Upload;
-use crate::models::user::User;
-use crate::services::media_token;
-use crate::state::AppState;
-
-#[derive(Deserialize)]
-pub struct MediaQuery {
-    pub exp: i64,
-    pub sig: String,
-}
-
-pub async fn serve(
-    State(state): State<AppState>,
-    Path((kind, id)): Path<(String, Uuid)>,
-    Query(q): Query<MediaQuery>,
-) -> Result<Response, AppError> {
-    if !media_token::verify(
-        &state.config.jwt_secret,
-        &kind,
-        id,
-        q.exp,
-        &q.sig,
-        Utc::now().timestamp(),
-    ) {
-        return Err(AppError::Unauthorized(
-            "Ungültige oder abgelaufene Medien-URL.".into(),
-        ));
-    }
-
-    // `find_by_id` filters `deleted_at IS NULL`, so soft-deleted uploads 404.
-    let upload = Upload::find_by_id(&state.pool, id)
-        .await?
-        .ok_or_else(|| AppError::NotFound("Datei nicht gefunden.".into()))?;
-
-    // Hide artifacts of users whose uploads were hidden by a host (ban + hide),
-    // matching the `usr.uploads_hidden = FALSE` predicate in `v_feed`.
-    let uploader = User::find_by_id(&state.pool, upload.user_id)
-        .await?
-        .ok_or_else(|| AppError::NotFound("Datei nicht gefunden.".into()))?;
-    if uploader.uploads_hidden {
-        return Err(AppError::NotFound("Datei nicht gefunden.".into()));
-    }
-
-    let (rel_path, content_type) = match kind.as_str() {
-        "original" => (upload.original_path.clone(), upload.mime_type.clone()),
-        "preview" => (
-            upload
-                .preview_path
-                .clone()
-                .ok_or_else(|| AppError::NotFound("Vorschau nicht verfügbar.".into()))?,
-            "image/jpeg".to_string(),
-        ),
-        "thumbnail" => (
-            upload
-                .thumbnail_path
-                .clone()
-                .ok_or_else(|| AppError::NotFound("Vorschau nicht verfügbar.".into()))?,
-            "image/jpeg".to_string(),
-        ),
-        _ => return Err(AppError::NotFound("Unbekannter Medientyp.".into())),
-    };
-
-    stream_file(&state.config.media_path.join(&rel_path), &content_type).await
-}
-
-async fn stream_file(path: &std::path::Path, content_type: &str) -> Result<Response, AppError> {
-    use axum::body::Body;
-    use axum::http::{header, StatusCode};
-    use tokio_util::io::ReaderStream;
-
-    let file = tokio::fs::File::open(path)
-        .await
-        .map_err(|_| AppError::NotFound("Datei nicht gefunden.".into()))?;
-    let metadata = file
-        .metadata()
-        .await
-        .map_err(|e| AppError::Internal(e.into()))?;
-    let stream = ReaderStream::new(file);
-
-    Response::builder()
-        .status(StatusCode::OK)
-        .header(header::CONTENT_TYPE, content_type)
-        .header(header::CONTENT_LENGTH, metadata.len())
-        // URLs are signed + time-boxed; cache only privately, aligned to the
-        // 1h URL-stability bucket.
-        .header(header::CACHE_CONTROL, "private, max-age=3600")
-        // Defense-in-depth against any active content slipping past the
-        // upload-time allowlist: never sniff, never script.
-        .header(header::X_CONTENT_TYPE_OPTIONS, "nosniff")
-        .header(
-            header::CONTENT_SECURITY_POLICY,
-            "default-src 'none'; sandbox; frame-ancestors 'none'",
-        )
-        .body(Body::from_stream(stream))
-        .map_err(|e| AppError::Internal(e.into()))
-}

backend/src/handlers/mod.rs

@@ -2,7 +2,7 @@ pub mod admin;
 pub mod feed;
 pub mod host;
 pub mod me;
-pub mod media;
+pub mod public;
 pub mod social;
 pub mod sse;
 pub mod test_admin;

backend/src/handlers/public.rs

@@ -0,0 +1,44 @@
+//! Unauthenticated, read-only endpoints safe to expose before a user has joined.
+
+use axum::Json;
+use axum::extract::State;
+use serde::Serialize;
+
+use crate::services::config;
+use crate::state::AppState;
+
+#[derive(Serialize)]
+pub struct PublicEventDto {
+    pub name: String,
+    pub slug: String,
+    /// Whether the comment feature is on (env `COMMENTS_ENABLED`). The frontend hides
+    /// the whole comment UI when false; exposed here so even the pre-auth shell knows.
+    pub comments_enabled: bool,
+    /// Active colour theme. `preset` is an id the frontend maps to a palette (or
+    /// "custom"); `primary`/`accent` are the `#rrggbb` seeds the ramps derive from.
+    /// Resolved as DB-config override → env default. Public so the theme applies on
+    /// the very first (pre-auth) paint without a flash.
+    pub theme_preset: String,
+    pub theme_primary: String,
+    pub theme_accent: String,
+}
+
+/// Public event identity + presentation config, used by the pre-auth join/recover
+/// screens (which event am I joining, what does it look like). Only non-user-scoped
+/// fields are exposed, so this is safe without a token. Identity comes straight from
+/// instance config; the theme is resolved from the runtime `config` table (admin UI)
+/// falling back to the env-seeded default.
+pub async fn get_public_event(State(state): State<AppState>) -> Json<PublicEventDto> {
+    let cache = &state.config_cache;
+    Json(PublicEventDto {
+        name: state.config.event_name.clone(),
+        slug: state.config.event_slug.clone(),
+        comments_enabled: state.config.comments_enabled,
+        theme_preset: config::get_str(cache, "theme_preset", &state.config.default_theme_preset)
+            .await,
+        theme_primary: config::get_str(cache, "theme_primary", &state.config.default_theme_primary)
+            .await,
+        theme_accent: config::get_str(cache, "theme_accent", &state.config.default_theme_accent)
+            .await,
+    })
+}

backend/src/handlers/social.rs

@@ -1,8 +1,8 @@
+use axum::Json;
 use axum::extract::{Path, Query, State};
 use axum::http::StatusCode;
-use axum::Json;
 use chrono::{DateTime, Utc};
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 use uuid::Uuid;
 
 use crate::auth::middleware::AuthUser;
@@ -10,21 +10,76 @@ use crate::error::AppError;
 use crate::models::comment::{Comment, CommentDto};
 use crate::models::hashtag::{self, Hashtag};
 use crate::models::upload::Upload;
+use crate::services::config;
 use crate::state::AppState;
 
+/// Throttle a social write. Keyed PER USER, like the feed and upload limits and for the same
+/// reason: at a venue every guest sits behind one NAT, so an IP key hands the whole party a
+/// single bucket and the most active guest starves everyone else.
+///
+/// These were the only mutating endpoints in the app with no limit at all — the coverage was
+/// asymmetric, not deliberately open. The ceiling is set well above anything a real guest
+/// produces; this bounds a script, not an enthusiastic double-tapper.
+async fn check_social_rate(state: &AppState, user_id: Uuid) -> Result<(), AppError> {
+    let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
+    let social_rate_on = config::get_bool(&state.config_cache, "social_rate_enabled", true).await;
+    if !(rate_limits_on && social_rate_on) {
+        return Ok(());
+    }
+    let rate_limit = config::get_usize(&state.config_cache, "social_rate_per_min", 120).await;
+    // ONE bucket across likes, comments and comment deletions. Separate buckets would let a
+    // caller triple the aggregate write rate just by alternating between them.
+    state
+        .rate_limiter
+        .check_with_retry(
+            format!("social:{user_id}"),
+            rate_limit,
+            std::time::Duration::from_secs(60),
+        )
+        .map_err(|retry_after_secs| {
+            AppError::TooManyRequests(
+                "Zu viele Aktionen. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            )
+        })
+}
+
+#[derive(Serialize)]
+pub struct LikeResponse {
+    /// The caller's like state *after* this toggle. The client sets `liked_by_me` from
+    /// this rather than blind-inverting local state — otherwise a second device (same
+    /// recovered user) drifts, since the `like-update` broadcast only carries `like_count`.
+    pub liked: bool,
+    /// Fresh like count, or `null` if the (best-effort) count query hiccuped. The client
+    /// keeps its current count when this is null rather than adopting a wrong number.
+    pub like_count: Option<i64>,
+}
+
 pub async fn toggle_like(
     State(state): State<AppState>,
     auth: AuthUser,
     Path(upload_id): Path<Uuid>,
-) -> Result<StatusCode, AppError> {
-    // Ban is already rejected by the AuthUser extractor. Scope the target to the
-    // caller's event and reject deleted uploads (M1: no cross-event IDOR, no
-    // likes on soft-deleted posts).
+) -> Result<Json<LikeResponse>, AppError> {
+    // Check if user is banned
+    let user = crate::models::user::User::find_by_id(&state.pool, auth.user_id)
+        .await?
+        .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;
+    if user.is_banned {
+        return Err(AppError::Forbidden("Du bist gesperrt.".into()));
+    }
+    check_social_rate(&state, auth.user_id).await?;
+
+    // Event-scope: the upload must belong to the caller's event (404 otherwise),
+    // matching the host handlers' find_by_id_and_event pattern.
     Upload::find_by_id_and_event(&state.pool, upload_id, auth.event_id)
         .await?
         .ok_or_else(|| AppError::NotFound("Upload nicht gefunden.".into()))?;
 
-    // Try to insert; if conflict, delete (toggle)
+    // NOTE: liking is intentionally allowed while the event is locked. Locking
+    // ("Event schließen") freezes *new uploads* only — likes, comments and
+    // browsing stay open (USER_JOURNEYS §9.3, FEATURES capability matrix).
+
+    // Try to insert; if conflict, delete (toggle). `liked` = the caller's state afterwards.
     let result = sqlx::query(
         "INSERT INTO \"like\" (upload_id, user_id) VALUES ($1, $2)
          ON CONFLICT (upload_id, user_id) DO NOTHING",
@@ -34,7 +89,8 @@ pub async fn toggle_like(
     .execute(&state.pool)
     .await?;
 
-    if result.rows_affected() == 0 {
+    let liked = result.rows_affected() > 0;
+    if !liked {
         // Already liked — remove
         sqlx::query("DELETE FROM \"like\" WHERE upload_id = $1 AND user_id = $2")
             .bind(upload_id)
@@ -43,13 +99,30 @@ pub async fn toggle_like(
             .await?;
     }
 
-    // Broadcast SSE
-    let _ = state.sse_tx.send(crate::state::SseEvent {
-        event_type: "like-update".to_string(),
-        data: serde_json::json!({ "upload_id": upload_id }).to_string(),
-    });
+    // Fresh count so feed clients can patch the single card in place instead of
+    // refetching page 1 (mirrors v_feed.like_count = COUNT(DISTINCT user_id)). The like
+    // itself is already committed, so a failed count must not fail the request — but we
+    // also must NOT broadcast/return a bogus 0 (that would push like_count: 0 to every
+    // client until the next event). On error we skip the broadcast and return null.
+    let like_count = sqlx::query_scalar::<_, i64>(
+        "SELECT COUNT(DISTINCT user_id) FROM \"like\" WHERE upload_id = $1",
+    )
+    .bind(upload_id)
+    .fetch_one(&state.pool)
+    .await
+    .ok();
 
-    Ok(StatusCode::NO_CONTENT)
+    if let Some(count) = like_count {
+        // Broadcast the new count so other clients patch their card. Only `like_count` is
+        // shared — each client's own `liked_by_me` only changes via its own toggle (which
+        // now reads it straight from this response).
+        let _ = state.sse_tx.send(crate::state::SseEvent {
+            event_type: "like-update".to_string(),
+            data: serde_json::json!({ "upload_id": upload_id, "like_count": count }).to_string(),
+        });
+    }
+
+    Ok(Json(LikeResponse { liked, like_count }))
 }
 
 #[derive(Deserialize, Default)]
@@ -68,8 +141,7 @@ pub async fn list_comments(
     Path(upload_id): Path<Uuid>,
     Query(q): Query<ListCommentsQuery>,
 ) -> Result<Json<Vec<CommentDto>>, AppError> {
-    // M1: a pure read behind any valid token must still be scoped to the
-    // caller's event and must not leak comments on soft-deleted uploads.
+    // Event-scope: only list comments for an upload in the caller's event.
     Upload::find_by_id_and_event(&state.pool, upload_id, auth.event_id)
         .await?
         .ok_or_else(|| AppError::NotFound("Upload nicht gefunden.".into()))?;
@@ -90,15 +162,28 @@ pub async fn add_comment(
     Path(upload_id): Path<Uuid>,
     Json(body): Json<AddCommentRequest>,
 ) -> Result<(StatusCode, Json<CommentDto>), AppError> {
-    // M1: scope the target upload to the caller's event and reject deleted
-    // posts. (Ban is already handled by the AuthUser extractor.)
-    Upload::find_by_id_and_event(&state.pool, upload_id, auth.event_id)
-        .await?
-        .ok_or_else(|| AppError::NotFound("Upload nicht gefunden.".into()))?;
+    // Comments can be disabled instance-wide (env COMMENTS_ENABLED). The frontend hides
+    // the UI, but gate the API too so a stale client or direct call can't slip one in.
+    if !state.config.comments_enabled {
+        return Err(AppError::Forbidden("Kommentare sind deaktiviert.".into()));
+    }
 
     let user = crate::models::user::User::find_by_id(&state.pool, auth.user_id)
         .await?
         .ok_or_else(|| AppError::NotFound("Benutzer nicht gefunden.".into()))?;
+    if user.is_banned {
+        return Err(AppError::Forbidden("Du bist gesperrt.".into()));
+    }
+    check_social_rate(&state, auth.user_id).await?;
+
+    // Event-scope: only comment on an upload that belongs to the caller's event.
+    Upload::find_by_id_and_event(&state.pool, upload_id, auth.event_id)
+        .await?
+        .ok_or_else(|| AppError::NotFound("Upload nicht gefunden.".into()))?;
+
+    // NOTE: commenting is intentionally allowed while the event is locked. Locking
+    // freezes *new uploads* only — likes, comments and browsing stay open
+    // (USER_JOURNEYS §9.3, FEATURES capability matrix).
 
     let text = body.body.trim();
     let text_chars = text.chars().count();
@@ -108,26 +193,48 @@ pub async fn add_comment(
         ));
     }
 
-    let comment = Comment::create(&state.pool, upload_id, auth.user_id, text).await?;
-
-    // Process hashtags in comment body
-    let tags = hashtag::extract_hashtags(text);
+    // Insert the comment and link its hashtags atomically, so a crash mid-loop
+    // can't leave a committed comment with only some of its tags indexed.
+    let mut tags = hashtag::extract_hashtags(text);
+    // Deterministic lock order, matching the upload path. `Hashtag::upsert` takes row locks,
+    // so two transactions touching the same two tags in OPPOSITE order deadlock — Postgres
+    // aborts one after ~1s and that guest's comment 500s. `extract_hashtags` returns them in
+    // text order, which is exactly the unordered case. Sort on the NORMALISED form, because
+    // that is the key `upsert` locks on.
+    tags.sort_by_key(|t| t.trim().trim_start_matches('#').to_lowercase());
+    tags.dedup_by_key(|t| t.trim().trim_start_matches('#').to_lowercase());
+    let mut tx = state.pool.begin().await?;
+    let comment = Comment::create(&mut *tx, upload_id, auth.user_id, text).await?;
     for tag in &tags {
-        let h = Hashtag::upsert(&state.pool, auth.event_id, tag).await?;
+        let h = Hashtag::upsert(&mut *tx, auth.event_id, tag).await?;
         sqlx::query(
             "INSERT INTO comment_hashtag (comment_id, hashtag_id) VALUES ($1, $2) ON CONFLICT DO NOTHING",
         )
         .bind(comment.id)
         .bind(h.id)
-        .execute(&state.pool)
+        .execute(&mut *tx)
         .await?;
     }
+    tx.commit().await?;
 
-    // Broadcast SSE
-    let _ = state.sse_tx.send(crate::state::SseEvent {
-        event_type: "new-comment".to_string(),
-        data: serde_json::json!({ "upload_id": upload_id }).to_string(),
-    });
+    // Fresh count so feed clients can patch the single card in place instead of
+    // refetching page 1 (mirrors v_feed.comment_count = COUNT(DISTINCT c.id); COUNT(*)
+    // over the same deleted_at filter is identical since comment.id is the PK). The
+    // count + broadcast are a UI optimisation — the comment is already committed, so a
+    // failure here must not fail the request. Swallow the error and skip the broadcast.
+    if let Ok(comment_count) = sqlx::query_scalar::<_, i64>(
+        "SELECT COUNT(*) FROM comment WHERE upload_id = $1 AND deleted_at IS NULL",
+    )
+    .bind(upload_id)
+    .fetch_one(&state.pool)
+    .await
+    {
+        let _ = state.sse_tx.send(crate::state::SseEvent {
+            event_type: "new-comment".to_string(),
+            data: serde_json::json!({ "upload_id": upload_id, "comment_count": comment_count })
+                .to_string(),
+        });
+    }
 
     let dto = CommentDto {
         id: comment.id,
@@ -146,6 +253,11 @@ pub async fn delete_comment(
     auth: AuthUser,
     Path(comment_id): Path<Uuid>,
 ) -> Result<StatusCode, AppError> {
+    // Banned users keep read access but cannot mutate (USER_JOURNEYS §10).
+    if auth.is_banned {
+        return Err(AppError::Forbidden("Du bist gesperrt.".into()));
+    }
+    check_social_rate(&state, auth.user_id).await?;
     let comment = Comment::find_by_id(&state.pool, comment_id)
         .await?
         .ok_or_else(|| AppError::NotFound("Kommentar nicht gefunden.".into()))?;
@@ -154,6 +266,27 @@ pub async fn delete_comment(
         return Err(AppError::Forbidden("Nur eigene Kommentare löschen.".into()));
     }
 
-    Comment::soft_delete(&state.pool, comment_id).await?;
+    // Event-scope: soft_delete_in_event only matches comments whose upload is in
+    // the caller's event, so a cross-event comment_id resolves to a 404 here.
+    let mut tx = state.pool.begin().await?;
+    let deleted = Comment::soft_delete_in_event(&mut tx, comment_id, auth.event_id).await?;
+    if !deleted {
+        return Err(AppError::NotFound("Kommentar nicht gefunden.".into()));
+    }
+    // Comments live only in the HTML viewer, so the ZIP is carried forward, not rebuilt.
+    let regen = crate::services::export::invalidate_and_arm(
+        &mut tx,
+        &state.config.event_slug,
+        crate::services::export::Affects::ViewerOnly,
+    )
+    .await?;
+    tx.commit().await?;
+    if let Some(r) = regen {
+        crate::handlers::host::start_regen(&state, r);
+    }
+    let _ = state.sse_tx.send(crate::state::SseEvent::new(
+        "comment-deleted",
+        serde_json::json!({ "comment_id": comment_id, "upload_id": comment.upload_id }).to_string(),
+    ));
     Ok(StatusCode::NO_CONTENT)
 }

backend/src/handlers/sse.rs

@@ -1,17 +1,19 @@
 use std::convert::Infallible;
 use std::time::Duration;
 
+use axum::Json;
 use axum::extract::{Query, State};
 use axum::response::sse::{Event, KeepAlive, Sse};
-use axum::Json;
 use futures::stream::Stream;
 use serde::{Deserialize, Serialize};
-use tokio_stream::wrappers::BroadcastStream;
 use tokio_stream::StreamExt;
+use tokio_stream::wrappers::BroadcastStream;
+use tokio_stream::wrappers::errors::BroadcastStreamRecvError;
 
 use crate::auth::middleware::AuthUser;
 use crate::error::AppError;
 use crate::models::session::Session;
+use crate::services::sse_tickets::TicketKind;
 use crate::state::AppState;
 
 #[derive(Deserialize)]
@@ -22,6 +24,10 @@ pub struct SseQuery {
 #[derive(Serialize)]
 pub struct StreamTicketResponse {
     pub ticket: String,
+    /// Server clock at mint time — the client seeds its SSE reconnect cursor from this
+    /// instead of `new Date()`, so a skewed browser clock can't drop uploads. See
+    /// `DeltaResponse::server_time`.
+    pub server_time: chrono::DateTime<chrono::Utc>,
 }
 
 /// Mint a short-lived single-use SSE ticket. The browser's `EventSource` cannot
@@ -32,9 +38,34 @@ pub struct StreamTicketResponse {
 pub async fn issue_ticket(
     State(state): State<AppState>,
     auth: AuthUser,
-) -> Json<StreamTicketResponse> {
-    let ticket = state.sse_tickets.issue(auth.token_hash);
-    Json(StreamTicketResponse { ticket })
+) -> Result<Json<StreamTicketResponse>, AppError> {
+    // The endpoint had no rate limit at all. Authentication is not a bound here: one valid
+    // session could loop it freely. 60/min is far above a real client (one ticket per SSE
+    // (re)connect, and reconnects are backed off) while capping a loop.
+    if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+        format!("sse_ticket:{}", auth.user_id),
+        60,
+        Duration::from_secs(60),
+    ) {
+        return Err(AppError::TooManyRequests(
+            "Zu viele Verbindungsversuche. Bitte warte kurz.".into(),
+            Some(retry_after_secs),
+        ));
+    }
+
+    let ticket = state.sse_tickets.issue(auth.token_hash, TicketKind::Sse).ok_or_else(|| {
+        AppError::ServiceUnavailable(
+            "Server ist gerade ausgelastet. Live-Updates folgen in Kürze.".into(),
+            Some(30),
+        )
+    })?;
+    let server_time = sqlx::query_scalar("SELECT NOW()")
+        .fetch_one(&state.pool)
+        .await?;
+    Ok(Json(StreamTicketResponse {
+        ticket,
+        server_time,
+    }))
 }
 
 /// SSE stream endpoint. Authenticates via a single-use ticket (see
@@ -45,22 +76,60 @@ pub async fn stream(
 ) -> Result<Sse<impl Stream<Item = Result<Event, Infallible>>>, AppError> {
     let token_hash = state
         .sse_tickets
-        .consume(&q.ticket)
+        .consume(&q.ticket, TicketKind::Sse)
         .ok_or_else(|| AppError::Unauthorized("Ticket ungültig oder abgelaufen.".into()))?;
 
+    // NOTE: this authenticates via ticket→session, not the `AuthUser` extractor. The
+    // SSE stream is read-only, and under the read-only-ban model (USER_JOURNEYS §10)
+    // banned users retain read access — so both minting a ticket and holding a stream
+    // open are intentionally allowed for banned users; only writes are blocked.
     Session::find_by_token_hash(&state.pool, &token_hash)
         .await
         .map_err(|e| AppError::Internal(e.into()))?
         .ok_or_else(|| AppError::Unauthorized("Sitzung nicht gefunden.".into()))?;
 
     let rx = state.sse_tx.subscribe();
-    let stream = BroadcastStream::new(rx).filter_map(|msg| match msg {
+    let events = BroadcastStream::new(rx).filter_map(|msg| match msg {
         Ok(sse_event) => Some(Ok(Event::default()
             .event(sse_event.event_type)
             .data(sse_event.data))),
-        Err(_) => None,
+        // A consumer that falls behind the broadcast buffer would otherwise silently
+        // lose events, leaving its feed permanently stale. Instead of dropping the
+        // gap, tell the client to resync — the frontend responds by running a full
+        // feed-delta fetch (which reconciles both new uploads and deletions).
+        Err(BroadcastStreamRecvError::Lagged(n)) => {
+            tracing::warn!("SSE consumer lagged, dropped {n} event(s); emitting resync");
+            Some(Ok(Event::default().event("resync").data(n.to_string())))
+        }
     });
 
+    // The session is only checked once at open. Re-validate it periodically so a
+    // logged-out, expired, OR banned session's stream is closed rather than kept alive
+    // until the client happens to disconnect. Bounds a stale stream to ~60s. NOTE: a ban is
+    // deliberately read-only and does NOT revoke sessions (see `ban_user`), so the
+    // `is_banned` re-read below is LOAD-BEARING — it is the only thing that stops a banned
+    // user's live push stream. Do not remove it. Only a *definitive* gone/expired/banned
+    // state ends the stream; a transient DB error just retries next tick.
+    let pool = state.pool.clone();
+    let session_hash = token_hash.clone();
+    let session_gone = async move {
+        let mut ticker = tokio::time::interval(Duration::from_secs(60));
+        ticker.tick().await; // consume the immediate first tick
+        loop {
+            ticker.tick().await;
+            match Session::find_user_by_token_hash(&pool, &session_hash).await {
+                Ok(Some(user)) if !user.is_banned => {} // still valid — keep streaming
+                Ok(Some(_)) => break,                   // banned — cut the stream
+                Ok(None) => break,                      // logged out or expired — stop
+                Err(e) => {
+                    tracing::warn!(error = ?e, "SSE session revalidation query failed; retrying");
+                }
+            }
+        }
+    };
+
+    let stream = futures::StreamExt::take_until(events, Box::pin(session_gone));
+
     Ok(Sse::new(stream).keep_alive(
         KeepAlive::new()
             .interval(Duration::from_secs(30))

backend/src/handlers/test_admin.rs

@@ -13,9 +13,10 @@ use crate::auth::middleware::RequireAdmin;
 use crate::error::AppError;
 use crate::state::AppState;
 
-/// Truncates every event-scoped table, wipes media on disk, and reseeds the
-/// `config` table from migration defaults. Requires an admin JWT — even with
-/// `EVENTSNAP_TEST_MODE=1` it cannot be hit anonymously.
+/// Truncates every event-scoped table, wipes media on disk, and reseeds the `config`
+/// table: numeric values from the migration defaults, but every feature toggle forced
+/// OFF (production seeds them ON — see the note at the reseed below). Requires an admin
+/// JWT — even with `EVENTSNAP_TEST_MODE=1` it cannot be hit anonymously.
 pub async fn truncate_all(
     State(state): State<AppState>,
     RequireAdmin(_auth): RequireAdmin,
@@ -40,15 +41,29 @@ pub async fn truncate_all(
     .execute(&state.pool)
     .await?;
 
-    // Reseed config — mirrors migrations 005 and 009. Kept in sync by hand
-    // because pulling SQL out of the migration files at runtime is fragile.
+    // Reseed config. The NUMERIC values mirror migrations 005/015/016/017/019; the BOOLEAN
+    // toggles deliberately do NOT — migration 009 seeds every one of them `true`
+    // (production), and this forces them `false` so the suite isn't fighting rate limits
+    // and quotas it isn't testing.
+    //
+    // Be aware of what that costs: this runs as an auto-fixture before EVERY test, so no
+    // test starts from production's config unless it explicitly turns a toggle back on
+    // (02-upload/rate-limit, 07-adversarial/ddos, 01-auth/rate-limit-nat, …). That blind
+    // spot is exactly why an entire class of per-IP limiter bugs went unnoticed: the
+    // limiters were simply off. When adding a limiter or quota, add a spec that enables it.
+    //
+    // Kept in sync by hand because pulling SQL out of the migration files at runtime is
+    // fragile — if you add a config key in a migration, add it here too.
     sqlx::query(
         r#"INSERT INTO config (key, value) VALUES
             ('max_image_size_mb',          '20'),
             ('max_video_size_mb',          '500'),
-            ('upload_rate_per_hour',       '10'),
+            ('upload_rate_per_hour',       '100'),
             ('feed_rate_per_min',          '60'),
             ('export_rate_per_day',        '3'),
+            ('join_ip_rate_per_min',       '60'),
+            ('recover_ip_rate_per_min',    '30'),
+            ('social_rate_per_min',        '120'),
             ('quota_tolerance',            '0.75'),
             ('estimated_guest_count',      '100'),
             ('compression_concurrency',    '2'),
@@ -57,6 +72,8 @@ pub async fn truncate_all(
             ('feed_rate_enabled',          'false'),
             ('export_rate_enabled',        'false'),
             ('join_rate_enabled',          'false'),
+            ('social_rate_enabled',        'false'),
+            ('admin_login_rate_enabled',   'false'),
             ('quota_enabled',              'false'),
             ('storage_quota_enabled',      'false'),
             ('upload_count_quota_enabled', 'false'),
@@ -70,10 +87,47 @@ pub async fn truncate_all(
     let _ = tokio::fs::remove_dir_all(&state.config.media_path).await;
     let _ = tokio::fs::create_dir_all(&state.config.media_path).await;
 
+    // Wipe the export directory too. Exports moved OUT of media_path (CR2 fix), so
+    // the media wipe above no longer covers them — without this a real export in
+    // one test would leave Gallery.zip on disk and contaminate the next.
+    let _ = tokio::fs::remove_dir_all(&state.config.export_path).await;
+    let _ = tokio::fs::create_dir_all(&state.config.export_path).await;
+
     // The rate limiter holds an in-memory HashMap; clear it so a previous test's
     // counters don't leak into the next one.
     state.rate_limiter.clear();
 
+    // The reseed above wrote the `config` table directly (bypassing patch_config), so
+    // the cache must be invalidated too — otherwise the first request after a truncate
+    // could serve the previous test's toggles.
+    state.config_cache.invalidate();
+
+    // The other two in-memory singletons that TRUNCATE used to leave standing.
+    //
+    // `disk_cache` holds a free-space reading for up to its TTL. TRUNCATE has just deleted every
+    // uploaded file, which materially changes free space — so without this the next test can
+    // compute a storage quota from the PREVIOUS test's disk. That was harmless only while quotas
+    // were globally disabled in e2e (they no longer are: see specs/02-upload/quota.spec.ts, which
+    // steers the per-user limit off `free_disk_bytes`), i.e. two holes were masking each other.
+    state.disk_cache.invalidate();
+
+    // `media_total` caches SUM(user.total_upload_bytes) for the upload gate's keepsake-headroom
+    // check. TRUNCATE has just zeroed every one of those rows, so a surviving reading would make
+    // the next test's first upload measure its headroom against the previous test's gallery —
+    // and that gate REFUSES uploads, so the failure would look like a spurious quota rejection.
+    state.media_total.invalidate();
+
+    // `sse_tickets` maps a ticket to a session token hash. TRUNCATE deletes the sessions, so every
+    // surviving ticket is a dangling reference to a user that no longer exists.
+    state.sse_tickets.clear();
+
+    // Invalidate any in-flight/queued compression task spawned by the previous test. Without this a
+    // task still waiting on the concurrency semaphore wakes AFTER this wipe, fails to find its
+    // (now-deleted) file, and broadcasts upload-error/upload-deleted into the NEXT test's SSE
+    // stream. (Export workers are already inert across a truncate: they are epoch-guarded on the
+    // event row, and truncate gives the event a fresh random UUID, so their writes match nothing.)
+    state.compression.bump_generation();
+
     Ok(StatusCode::NO_CONTENT)
 }
 

backend/src/main.rs

@@ -1,7 +1,7 @@
 use anyhow::Result;
+use axum::Router;
 use axum::extract::DefaultBodyLimit;
 use axum::routing::{delete, get, patch, post};
-use axum::Router;
 use tower_http::trace::TraceLayer;
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
 
@@ -17,14 +17,26 @@ mod state;
 use config::AppConfig;
 use state::AppState;
 
+/// Hard HTTP body cap for the upload endpoint (576 MiB). Backstop against
+/// memory-exhaustion; precise per-class size limits are enforced in the handler.
+const MAX_UPLOAD_BYTES: usize = 576 * 1024 * 1024;
+
 #[tokio::main]
 async fn main() -> Result<()> {
     dotenvy::dotenv().ok();
 
     tracing_subscriber::registry()
-        .with(tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| {
-            "eventsnap_backend=debug,tower_http=debug".into()
-        }))
+        .with(
+            // `info`, not `debug`. A stock deploy sets RUST_LOG nowhere (it is absent from
+            // .env.example and was absent from docker-compose.yml), so this fallback IS the
+            // production level — and at `debug` the TraceLayer below emits a line per request
+            // AND per response, into a log file that had no rotation. `tower_http=warn`
+            // rather than `info` states the intent: those spans are diagnostics, not an
+            // access log, and a future `DefaultOnResponse::new().level(Level::INFO)` should
+            // not silently re-enable them.
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| "eventsnap_backend=info,tower_http=warn".into()),
+        )
         .with(tracing_subscriber::fmt::layer())
         .init();
 
@@ -39,6 +51,32 @@ async fn main() -> Result<()> {
 
     let state = AppState::new(pool.clone(), config.clone());
 
+    // Regenerate image derivatives an older pipeline produced: the big-screen display for
+    // uploads processed before it existed (v0.17.x), and anything predating the current
+    // DERIVATIVES_REV (rev 1 applies the EXIF orientation, without which every portrait
+    // phone photo is stored sideways). Fire-and-forget behind the compression semaphore;
+    // originals are never touched, so a failure just retries on the next start.
+    state.compression.backfill_stale_derivatives().await;
+
+    // Re-extract poster frames for videos a restart interrupted. `startup_recovery` above
+    // marks their compression `failed` but nothing re-enqueued them, so `thumbnail_path`
+    // stayed NULL for the rest of the event. Shares the attempt budget with the image
+    // backfill, so a clip that genuinely yields no frame stops being retried.
+    state.compression.backfill_video_posters().await;
+
+    // Re-spawn exports for events that were released but whose keepsake never finished
+    // (crash mid-export). Needs the media/export paths + SSE sender, so it runs here
+    // rather than inside `startup_recovery`. Fire-and-forget: the workers run in the
+    // background; the HTTP server can start accepting requests meanwhile.
+    services::export::recover_exports(
+        pool.clone(),
+        config.media_path.clone(),
+        config.export_path.clone(),
+        config.comments_enabled,
+        state.sse_tx.clone(),
+    )
+    .await;
+
     // Hourly background hygiene: prune expired sessions, evict cold rate-limiter
     // keys. Keeps the DB and process from growing unboundedly over multi-day events.
     services::maintenance::spawn_periodic_tasks(
@@ -53,19 +91,50 @@ async fn main() -> Result<()> {
 
     let api = Router::new()
         // Auth
+        .route("/api/v1/event", get(handlers::public::get_public_event))
         .route("/api/v1/join", post(auth::handlers::join))
         .route("/api/v1/recover", post(auth::handlers::recover))
+        // Forgotten-PIN escape hatch: ask a host to reset it (unauthenticated, throttled).
+        .route(
+            "/api/v1/recover/request",
+            post(auth::handlers::request_pin_reset),
+        )
         .route("/api/v1/admin/login", post(auth::handlers::admin_login))
         .route("/api/v1/session", delete(auth::handlers::logout))
-        // Upload — cap the request body so a single request can't buffer the box
-        // into OOM. Sized to the largest allowed video (500 MB) plus multipart
-        // overhead; the per-category limit is still enforced inside the handler.
-        .route("/api/v1/upload", post(handlers::upload::upload)
-            .route_layer(DefaultBodyLimit::max(550 * 1024 * 1024)))
+        // "Sign out everywhere" — revoke all of the caller's sessions.
+        .route("/api/v1/sessions", delete(auth::handlers::logout_all))
+        // Upload — HTTP-level body cap as an OOM backstop. The handler still enforces
+        // the precise per-class limits from DB config (max_image/video_size_mb); this
+        // layer just stops a multi-GB body from being buffered into memory before that
+        // check runs. Sized generously above the default 500 MB video limit + multipart
+        // overhead — if an admin raises max_video_size_mb above this, bump MAX_UPLOAD_BYTES.
+        .route(
+            "/api/v1/upload",
+            post(handlers::upload::upload).route_layer(DefaultBodyLimit::max(MAX_UPLOAD_BYTES)),
+        )
         .route(
             "/api/v1/upload/{id}",
             patch(handlers::upload::edit_upload).delete(handlers::upload::delete_upload),
         )
+        .route(
+            "/api/v1/upload/{id}/original",
+            get(handlers::upload::get_original),
+        )
+        // Preview/thumbnail variants are gated the same way as originals (visibility
+        // check + direct /media block below) so moderation actually revokes access to
+        // the displayed images, not just the full-res download.
+        .route(
+            "/api/v1/upload/{id}/preview",
+            get(handlers::upload::get_preview),
+        )
+        .route(
+            "/api/v1/upload/{id}/display",
+            get(handlers::upload::get_display),
+        )
+        .route(
+            "/api/v1/upload/{id}/thumbnail",
+            get(handlers::upload::get_thumbnail),
+        )
         // Current-user endpoints (live quota estimate, profile + privacy note bundle)
         .route("/api/v1/me/context", get(handlers::me::get_context))
         .route("/api/v1/me/quota", get(handlers::me::get_quota))
@@ -73,33 +142,79 @@ async fn main() -> Result<()> {
         .route("/api/v1/feed", get(handlers::feed::feed))
         .route("/api/v1/feed/delta", get(handlers::feed::feed_delta))
         .route("/api/v1/hashtags", get(handlers::feed::hashtags))
+        .route("/api/v1/uploaders", get(handlers::feed::uploaders))
         // Social
-        .route("/api/v1/upload/{id}/like", post(handlers::social::toggle_like))
+        .route(
+            "/api/v1/upload/{id}/like",
+            post(handlers::social::toggle_like),
+        )
         .route(
             "/api/v1/upload/{id}/comments",
             get(handlers::social::list_comments).post(handlers::social::add_comment),
         )
-        .route("/api/v1/comment/{id}", delete(handlers::social::delete_comment))
+        .route(
+            "/api/v1/comment/{id}",
+            delete(handlers::social::delete_comment),
+        )
         // SSE
         .route("/api/v1/stream", get(handlers::sse::stream))
         .route("/api/v1/stream/ticket", post(handlers::sse::issue_ticket))
         // Host Dashboard
         .route("/api/v1/host/event", get(handlers::host::get_event_status))
-        .route("/api/v1/host/event/close", post(handlers::host::close_event))
+        .route(
+            "/api/v1/host/event/close",
+            post(handlers::host::close_event),
+        )
         .route("/api/v1/host/event/open", post(handlers::host::open_event))
-        .route("/api/v1/host/gallery/release", post(handlers::host::release_gallery))
+        .route(
+            "/api/v1/host/gallery/release",
+            post(handlers::host::release_gallery),
+        )
+        // Escape hatch: force a keepsake rebuild. Without it a failed export is terminal at runtime
+        // (release_gallery refuses an already-released event; recovery only runs at boot).
+        .route(
+            "/api/v1/host/export/rebuild",
+            post(handlers::host::rebuild_export),
+        )
         .route("/api/v1/host/users", get(handlers::host::list_users))
-        .route("/api/v1/host/users/{id}/ban", post(handlers::host::ban_user))
-        .route("/api/v1/host/users/{id}/unban", post(handlers::host::unban_user))
-        .route("/api/v1/host/users/{id}/role", patch(handlers::host::set_role))
+        .route(
+            "/api/v1/host/users/{id}/ban",
+            post(handlers::host::ban_user),
+        )
+        .route(
+            "/api/v1/host/users/{id}/unban",
+            post(handlers::host::unban_user),
+        )
+        .route(
+            "/api/v1/host/users/{id}/role",
+            patch(handlers::host::set_role),
+        )
         .route(
             "/api/v1/host/users/{id}/pin-reset",
             post(handlers::host::reset_user_pin),
         )
-        .route("/api/v1/host/upload/{id}", delete(handlers::host::host_delete_upload))
-        .route("/api/v1/host/comment/{id}", delete(handlers::host::host_delete_comment))
+        .route(
+            "/api/v1/host/pin-reset-requests",
+            get(handlers::host::list_pin_reset_requests),
+        )
+        .route(
+            "/api/v1/host/pin-reset-requests/{id}",
+            delete(handlers::host::dismiss_pin_reset_request),
+        )
+        .route(
+            "/api/v1/host/upload/{id}",
+            delete(handlers::host::host_delete_upload),
+        )
+        .route(
+            "/api/v1/host/comment/{id}",
+            delete(handlers::host::host_delete_comment),
+        )
         // Export (all authenticated users)
         .route("/api/v1/export/status", get(handlers::admin::export_status))
+        .route(
+            "/api/v1/export/ticket",
+            post(handlers::admin::export_ticket),
+        )
         .route("/api/v1/export/zip", get(handlers::admin::download_zip))
         .route("/api/v1/export/html", get(handlers::admin::download_html))
         // Admin Dashboard
@@ -108,7 +223,10 @@ async fn main() -> Result<()> {
             "/api/v1/admin/config",
             get(handlers::admin::get_config).patch(handlers::admin::patch_config),
         )
-        .route("/api/v1/admin/export/jobs", get(handlers::admin::get_export_jobs));
+        .route(
+            "/api/v1/admin/export/jobs",
+            get(handlers::admin::get_export_jobs),
+        );
 
     // Test-only route: a hard reset for the Playwright E2E harness. The handler
     // is compiled in always, but the route is only attached when
@@ -127,33 +245,157 @@ async fn main() -> Result<()> {
         api
     };
 
-    // Media is served exclusively through the authenticated, signed gateway —
-    // there is no raw static mount. The gateway verifies an HMAC signature and
-    // consults the DB (deleted / ban-hidden / type), so private artifacts and
-    // the export archives are never reachable by guessing a path.
-    // Trace spans log the request *path* only, never the query string — signed
-    // media URLs carry a replayable `?sig=` capability that must not land in
-    // access logs.
-    let trace_layer = TraceLayer::new_for_http().make_span_with(
-        |req: &axum::http::Request<axum::body::Body>| {
-            tracing::info_span!(
-                "request",
-                method = %req.method(),
-                path = %req.uri().path(),
-            )
-        },
-    );
-
+    // NOTE: media is deliberately NOT served over HTTP.
+    //
+    // Files live under `media_path` so the compression worker and the export job can read
+    // them off disk, but nothing may pull them straight from `/media/**` — that bypasses
+    // the visibility checks (soft-delete + ban-hide) that make a host takedown stick.
+    // Every legitimate fetch goes through `/api/v1/upload/{id}/{original,preview,display,
+    // thumbnail}`, which filter via `find_visible_media`; those are the only media URLs the
+    // backend ever emits (see `handlers::feed`).
+    //
+    // This used to be a `ServeDir` on `/media` with four `nest_service` blockers on the
+    // subtrees above it. That was bypassable: axum routes on the RAW path while `ServeDir`
+    // percent-decodes afterwards, so `/media/%70reviews/{id}.jpg` missed every blocker,
+    // fell through to the `ServeDir`, and was decoded back to `previews/` on disk — serving
+    // a taken-down photo to anyone, unauthenticated. Any single escaped byte worked, in all
+    // four subtrees. Deleting the route removes the vector outright rather than racing the
+    // decoder; `/media/**` now 404s regardless of encoding.
     let router = Router::new()
-        .route("/health", get(|| async { "ok" }))
+        // ONE probe, and it touches the database. The merge of the unattended-blockers work
+        // brought a competing design — a dependency-free `/health` for the compose gate plus
+        // a DB-backed `/health/ready` for an external monitor. That split is defensible, and
+        // it was rejected deliberately:
+        //
+        //   * `/health` returning a constant "ok" is the exact defect faea555 fixed and
+        //     verified live (stop Postgres → 503 → start → 200, with no app restart). Every
+        //     request path touches the database, so a constant probe reports healthy while
+        //     the app is useless — the disk-full endgame stayed green all the way down.
+        //   * The split's motive was that Caddy's `depends_on: app: service_healthy` would
+        //     be blocked by a Postgres hiccup at boot. But `app` itself already gates on
+        //     `db: service_healthy`, so the DB is up before this probe ever runs, and the
+        //     healthcheck carries a 20s start_period plus 5 retries on top.
+        //   * The two handlers were the same `SELECT 1` with the same 2s timeout under two
+        //     names, so keeping both bought nothing.
+        //
+        // The external uptime monitor the runbook now calls for points at this route.
+        .route("/health", get(health))
         .merge(api)
-        .route("/media/{kind}/{id}", get(handlers::media::serve))
-        .layer(trace_layer)
+        .layer(TraceLayer::new_for_http())
         .with_state(state);
 
     let listener = tokio::net::TcpListener::bind(("0.0.0.0", config.app_port)).await?;
     tracing::info!("listening on {}", listener.local_addr()?);
-    axum::serve(listener, router).await?;
+    // `into_make_service_with_connect_info` is required by the pre-auth handlers, which
+    // extract `ConnectInfo<SocketAddr>` to use the peer address as the rate-limit key when
+    // X-Forwarded-For is absent. Without it those extractors fail at runtime.
+    axum::serve(
+        listener,
+        router.into_make_service_with_connect_info::<std::net::SocketAddr>(),
+    )
+    .with_graceful_shutdown(shutdown_signal())
+    .await?;
 
     Ok(())
 }
+
+/// How long `/health` waits for the database before calling the app unhealthy. Deliberately
+/// short: the point is to answer "can this process actually serve a request right now", and a
+/// probe that blocks for the acquire timeout is itself a symptom.
+const HEALTH_DB_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(2);
+
+/// Readiness probe — the Docker healthcheck, Caddy's `depends_on` gate, and the runbook's
+/// event-day `curl` all hit this.
+///
+/// It used to return the literal string `"ok"` and touch nothing. Every request in the app needs
+/// the database, so that answered a question nobody asked: the container reported healthy while
+/// every real request 500'd, and with no operator watching during the event there was no signal
+/// at all. Note what this does NOT buy: Compose's `restart: unless-stopped` does not react to
+/// healthcheck state, so nothing restarts on a red probe — this is a diagnostic, and it is
+/// deliberately not wired to automatic recovery, because the pool already heals itself across a
+/// Postgres restart (sqlx revalidates on acquire) and an auto-restart would truncate every
+/// in-flight upload to "fix" an outage that was about to clear on its own.
+async fn health(
+    axum::extract::State(state): axum::extract::State<AppState>,
+) -> impl axum::response::IntoResponse {
+    use axum::http::StatusCode;
+    match tokio::time::timeout(
+        HEALTH_DB_TIMEOUT,
+        sqlx::query("SELECT 1").execute(&state.pool),
+    )
+    .await
+    {
+        Ok(Ok(_)) => (StatusCode::OK, "ok"),
+        Ok(Err(e)) => {
+            tracing::error!(error = ?e, "health check: database query failed");
+            (StatusCode::SERVICE_UNAVAILABLE, "database unavailable")
+        }
+        Err(_) => {
+            tracing::error!(
+                timeout_s = HEALTH_DB_TIMEOUT.as_secs(),
+                "health check: database did not respond"
+            );
+            (StatusCode::SERVICE_UNAVAILABLE, "database timeout")
+        }
+    }
+}
+
+/// Hard cap on how long we wait for in-flight connections to drain after a shutdown
+/// signal. Uploads (streamed to disk) finish in well under this; the cap exists because
+/// long-lived SSE streams never end on their own and would otherwise keep the graceful
+/// drain — and thus the process — pending until the orchestrator force-kills it.
+const SHUTDOWN_GRACE: std::time::Duration = std::time::Duration::from_secs(10);
+
+/// Resolves on SIGINT (Ctrl-C) or SIGTERM (container stop / deploy). Letting
+/// `axum::serve` drain in-flight requests on this signal means a redeploy no longer
+/// truncates uploads mid-flight; any background compression/export half-states that a
+/// hard kill would leave are already reconciled by `startup_recovery` on the next boot.
+///
+/// Once the signal fires we also arm a detached backstop that force-exits after
+/// [`SHUTDOWN_GRACE`]. Without it, open SSE streams (which have no natural end) would
+/// hold the graceful drain open indefinitely; the backstop bounds shutdown regardless
+/// of the orchestrator's own kill timeout. If the drain completes first, `main` returns
+/// and the process exits before the timer ever fires.
+async fn shutdown_signal() {
+    let ctrl_c = async {
+        let _ = tokio::signal::ctrl_c().await;
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        match tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate()) {
+            Ok(mut sig) => {
+                sig.recv().await;
+            }
+            Err(e) => {
+                tracing::warn!(error = ?e, "failed to install SIGTERM handler");
+                // Never resolve — fall back to ctrl_c only.
+                std::future::pending::<()>().await;
+            }
+        }
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {}
+        _ = terminate => {}
+    }
+
+    tracing::info!(
+        "shutdown signal received, draining in-flight requests (max {}s)",
+        SHUTDOWN_GRACE.as_secs()
+    );
+
+    // Backstop: if the graceful drain is still blocked after the grace window (almost
+    // always because SSE streams are still open), exit anyway so deploys aren't stalled.
+    tokio::spawn(async {
+        tokio::time::sleep(SHUTDOWN_GRACE).await;
+        tracing::warn!(
+            "graceful drain exceeded {}s (likely open SSE streams); forcing exit",
+            SHUTDOWN_GRACE.as_secs()
+        );
+        std::process::exit(0);
+    });
+}

backend/src/models/comment.rs

@@ -3,6 +3,10 @@ use serde::Serialize;
 use sqlx::PgPool;
 use uuid::Uuid;
 
+// Row shape for `comment`: every field is populated by sqlx from `SELECT *` / `RETURNING *`.
+// `deleted_at` is not read in Rust today (the soft-delete filter lives in SQL), but it is part of
+// the row and stays here so the struct keeps mirroring the table.
+#[allow(dead_code)]
 #[derive(Debug, sqlx::FromRow)]
 pub struct Comment {
     pub id: Uuid,
@@ -24,19 +28,24 @@ pub struct CommentDto {
 }
 
 impl Comment {
-    pub async fn create(
-        pool: &PgPool,
+    /// Takes any executor so the caller can insert the comment and link its
+    /// hashtags inside a single transaction.
+    pub async fn create<'e, E>(
+        executor: E,
         upload_id: Uuid,
         user_id: Uuid,
         body: &str,
-    ) -> Result<Self, sqlx::Error> {
+    ) -> Result<Self, sqlx::Error>
+    where
+        E: sqlx::PgExecutor<'e>,
+    {
         sqlx::query_as::<_, Self>(
             "INSERT INTO comment (upload_id, user_id, body) VALUES ($1, $2, $3) RETURNING *",
         )
         .bind(upload_id)
         .bind(user_id)
         .bind(body)
-        .fetch_one(pool)
+        .fetch_one(executor)
         .await
     }
 
@@ -74,26 +83,18 @@ impl Comment {
     }
 
     pub async fn find_by_id(pool: &PgPool, id: Uuid) -> Result<Option<Self>, sqlx::Error> {
-        sqlx::query_as::<_, Self>(
-            "SELECT * FROM comment WHERE id = $1 AND deleted_at IS NULL",
-        )
-        .bind(id)
-        .fetch_optional(pool)
-        .await
-    }
-
-    pub async fn soft_delete(pool: &PgPool, id: Uuid) -> Result<(), sqlx::Error> {
-        sqlx::query("UPDATE comment SET deleted_at = NOW() WHERE id = $1")
+        sqlx::query_as::<_, Self>("SELECT * FROM comment WHERE id = $1 AND deleted_at IS NULL")
             .bind(id)
-            .execute(pool)
-            .await?;
-        Ok(())
+            .fetch_optional(pool)
+            .await
     }
 
-    /// Event-scoped variant of [`Self::soft_delete`]. Returns `false` if the
-    /// comment doesn't exist or belongs to a different event.
+    /// Event-scoped soft delete. Returns `false` if the comment doesn't exist or belongs to a
+    /// different event.
+    /// Executor-generic so the delete and the keepsake regeneration can share one transaction
+    /// (see `Upload::soft_delete_in_event` for why that must be atomic).
     pub async fn soft_delete_in_event(
-        pool: &PgPool,
+        conn: &mut sqlx::PgConnection,
         id: Uuid,
         event_id: Uuid,
     ) -> Result<bool, sqlx::Error> {
@@ -106,7 +107,7 @@ impl Comment {
         )
         .bind(id)
         .bind(event_id)
-        .execute(pool)
+        .execute(conn)
         .await?;
         Ok(result.rows_affected() > 0)
     }

backend/src/models/event.rs

@@ -2,6 +2,11 @@ use chrono::{DateTime, Utc};
 use sqlx::PgPool;
 use uuid::Uuid;
 
+// Row shape for `event`: every field is populated by sqlx from `SELECT *` / `RETURNING *`. Several
+// (`slug`, `cover_image_path`, `export_epoch`, `created_at`) are not read through this struct today
+// — callers that need them query the column directly — but they are part of the row and stay here so
+// the struct keeps mirroring the table.
+#[allow(dead_code)]
 #[derive(Debug, sqlx::FromRow)]
 pub struct Event {
     pub id: Uuid,
@@ -11,8 +16,11 @@ pub struct Event {
     pub is_active: bool,
     pub uploads_locked_at: Option<DateTime<Utc>>,
     pub export_released_at: Option<DateTime<Utc>>,
-    pub export_zip_ready: bool,
-    pub export_html_ready: bool,
+    /// Monotonic generation counter for the keepsake. Bumped in the SAME UPDATE as any change to
+    /// `export_released_at` (release and reopen are its only writers). An export is downloadable
+    /// iff a `done` `export_job` row carries this exact epoch — readiness is derived from that,
+    /// never stored, so it cannot drift and no worker can resurrect it. See migration 014.
+    pub export_epoch: i64,
     pub created_at: DateTime<Utc>,
 }
 
@@ -25,13 +33,11 @@ impl Event {
     }
 
     pub async fn create(pool: &PgPool, slug: &str, name: &str) -> Result<Self, sqlx::Error> {
-        sqlx::query_as::<_, Self>(
-            "INSERT INTO event (slug, name) VALUES ($1, $2) RETURNING *",
-        )
-        .bind(slug)
-        .bind(name)
-        .fetch_one(pool)
-        .await
+        sqlx::query_as::<_, Self>("INSERT INTO event (slug, name) VALUES ($1, $2) RETURNING *")
+            .bind(slug)
+            .bind(name)
+            .fetch_one(pool)
+            .await
     }
 
     pub async fn find_or_create(

backend/src/models/hashtag.rs

@@ -1,6 +1,8 @@
-use sqlx::PgPool;
 use uuid::Uuid;
 
+// Row shape for `hashtag`, populated by sqlx from `RETURNING *` in `upsert`. Callers only use
+// `id` today; `event_id`/`tag` are the rest of the row and stay part of the struct.
+#[allow(dead_code)]
 #[derive(Debug, sqlx::FromRow)]
 pub struct Hashtag {
     pub id: Uuid,
@@ -10,7 +12,13 @@ pub struct Hashtag {
 
 impl Hashtag {
     /// Upsert a hashtag (insert if not exists, return existing if it does).
-    pub async fn upsert(pool: &PgPool, event_id: Uuid, tag: &str) -> Result<Self, sqlx::Error> {
+    ///
+    /// Takes any executor so callers can run it inside a transaction (atomic
+    /// upload/comment writes) or standalone against the pool.
+    pub async fn upsert<'e, E>(executor: E, event_id: Uuid, tag: &str) -> Result<Self, sqlx::Error>
+    where
+        E: sqlx::PgExecutor<'e>,
+    {
         let normalized = tag.trim().trim_start_matches('#').to_lowercase();
         sqlx::query_as::<_, Self>(
             "INSERT INTO hashtag (event_id, tag) VALUES ($1, $2)
@@ -19,51 +27,68 @@ impl Hashtag {
         )
         .bind(event_id)
         .bind(&normalized)
-        .fetch_one(pool)
+        .fetch_one(executor)
         .await
     }
 
-    pub async fn link_to_upload(
-        pool: &PgPool,
+    pub async fn link_to_upload<'e, E>(
+        executor: E,
         upload_id: Uuid,
         hashtag_id: Uuid,
-    ) -> Result<(), sqlx::Error> {
+    ) -> Result<(), sqlx::Error>
+    where
+        E: sqlx::PgExecutor<'e>,
+    {
         sqlx::query(
             "INSERT INTO upload_hashtag (upload_id, hashtag_id) VALUES ($1, $2)
              ON CONFLICT DO NOTHING",
         )
         .bind(upload_id)
         .bind(hashtag_id)
-        .execute(pool)
+        .execute(executor)
         .await?;
         Ok(())
     }
 
-    pub async fn unlink_all_from_upload(
-        pool: &PgPool,
+    pub async fn unlink_all_from_upload<'e, E>(
+        executor: E,
         upload_id: Uuid,
-    ) -> Result<(), sqlx::Error> {
+    ) -> Result<(), sqlx::Error>
+    where
+        E: sqlx::PgExecutor<'e>,
+    {
         sqlx::query("DELETE FROM upload_hashtag WHERE upload_id = $1")
             .bind(upload_id)
-            .execute(pool)
+            .execute(executor)
             .await?;
         Ok(())
     }
 
-    pub async fn tags_for_upload(
-        pool: &PgPool,
+    /// The upload's current tags, lowercased and sorted — the comparable form.
+    ///
+    /// Exists so `edit_upload` can tell a real hashtag change from a re-send of the same list.
+    /// Without it, `PATCH {"hashtags": []}` in a loop retired the HTML keepsake on every request
+    /// (readiness is derived from `event.export_epoch`), and every armed rebuild was superseded
+    /// before the debounce let it start — so the viewer 404'd for the rest of the event at zero
+    /// cost to the client. One indexed lookup on `upload_hashtag(upload_id)` is a fair price for
+    /// closing that.
+    pub async fn normalized_for_upload<'e, E>(
+        executor: E,
         upload_id: Uuid,
-    ) -> Result<Vec<String>, sqlx::Error> {
+    ) -> Result<Vec<String>, sqlx::Error>
+    where
+        E: sqlx::PgExecutor<'e>,
+    {
         let rows: Vec<(String,)> = sqlx::query_as(
-            "SELECT h.tag FROM hashtag h
+            "SELECT lower(h.tag) FROM hashtag h
              JOIN upload_hashtag uh ON uh.hashtag_id = h.id
              WHERE uh.upload_id = $1
-             ORDER BY h.tag",
+             ORDER BY lower(h.tag)",
         )
         .bind(upload_id)
-        .fetch_all(pool)
+        .fetch_all(executor)
         .await?;
-        Ok(rows.into_iter().map(|r| r.0).collect())
+        Ok(rows.into_iter().map(|(t,)| t).collect())
     }
 }
 
@@ -109,4 +134,44 @@ mod tests {
     fn empty_or_bare_hash_skipped() {
         assert_eq!(extract_hashtags("# #"), Vec::<String>::new());
     }
+
+    #[test]
+    fn tag_stops_at_first_non_word_char() {
+        // A tag runs until the first char that isn't ascii-alphanumeric or '_'.
+        assert_eq!(extract_hashtags("#foo#bar"), vec!["foo"]);
+        assert_eq!(extract_hashtags("#foo-bar"), vec!["foo"]);
+        assert_eq!(extract_hashtags("##tag"), Vec::<String>::new()); // '#' after the strip is non-word
+    }
+
+    #[test]
+    fn tag_length_is_capped_at_40_chars() {
+        let ok = "a".repeat(40);
+        assert_eq!(extract_hashtags(&format!("#{ok}")), vec![ok.clone()]);
+        // 41+ chars → dropped entirely (not truncated).
+        let too_long = "a".repeat(41);
+        assert_eq!(
+            extract_hashtags(&format!("#{too_long}")),
+            Vec::<String>::new()
+        );
+    }
+
+    #[test]
+    fn duplicate_tags_are_returned_verbatim_not_deduplicated() {
+        // Dedup is the DB's job (Hashtag::upsert ON CONFLICT); extraction returns each
+        // occurrence so callers can count/link them independently. Case folds to lower.
+        assert_eq!(
+            extract_hashtags("#fun #Fun #fun!"),
+            vec!["fun", "fun", "fun"]
+        );
+    }
+
+    #[test]
+    fn non_ascii_word_chars_truncate_the_tag() {
+        // KNOWN LIMITATION for a German app: `is_ascii_alphanumeric` excludes umlauts
+        // and ß, so a tag truncates at the first non-ASCII letter. Pinned here so a
+        // future Unicode-aware change is a deliberate, test-visible decision.
+        assert_eq!(extract_hashtags("#Grüße"), vec!["gr"]);
+        assert_eq!(extract_hashtags("#Straße"), vec!["stra"]);
+        assert_eq!(extract_hashtags("#café"), vec!["caf"]);
+    }
 }

backend/src/models/session.rs

@@ -2,8 +2,9 @@ use chrono::{DateTime, Utc};
 use sqlx::PgPool;
 use uuid::Uuid;
 
-use crate::models::user::UserRole;
-
+// Row shape for `session`, populated by sqlx from `RETURNING *`. Session validation is done in SQL
+// (expiry/last-seen predicates), so no field is read in Rust — the struct is the row's shape.
+#[allow(dead_code)]
 #[derive(Debug, sqlx::FromRow)]
 pub struct Session {
     pub id: Uuid,
@@ -14,18 +15,6 @@ pub struct Session {
     pub created_at: DateTime<Utc>,
 }
 
-/// Live identity reconciled from the DB for a valid, unexpired session. Used by
-/// the `AuthUser` extractor so role/ban/event are sourced from the `user` row
-/// rather than trusted from (potentially stale) JWT claims.
-#[derive(Debug, sqlx::FromRow)]
-pub struct AuthContext {
-    pub session_id: Uuid,
-    pub user_id: Uuid,
-    pub event_id: Uuid,
-    pub role: UserRole,
-    pub is_banned: bool,
-}
-
 impl Session {
     pub async fn create(
         pool: &PgPool,
@@ -57,16 +46,19 @@ impl Session {
         .await
     }
 
-    /// Reconcile a session against the live `user` row in a single round-trip.
-    /// Returns `None` when the session is missing/expired. The PK join to
-    /// `"user"` is cheap and lets the extractor read the *current* role/ban
-    /// state instead of the JWT claim.
-    pub async fn find_auth_context(
+    /// Resolve a session token straight to its live user row in one round-trip.
+    ///
+    /// The auth extractor runs on every authenticated request and used to do two
+    /// sequential queries (session lookup, then user lookup); this collapses them into
+    /// a single `session JOIN "user"`. The `expires_at` guard mirrors
+    /// [`Self::find_by_token_hash`], and the user row is read live (role/ban are never
+    /// trusted from the JWT). Returns `None` when the session is missing/expired.
+    pub async fn find_user_by_token_hash(
         pool: &PgPool,
         token_hash: &str,
-    ) -> Result<Option<AuthContext>, sqlx::Error> {
-        sqlx::query_as::<_, AuthContext>(
-            "SELECT s.id AS session_id, u.id AS user_id, u.event_id, u.role, u.is_banned
+    ) -> Result<Option<crate::models::user::User>, sqlx::Error> {
+        sqlx::query_as::<_, crate::models::user::User>(
+            "SELECT u.*
              FROM session s
              JOIN \"user\" u ON u.id = s.user_id
              WHERE s.token_hash = $1 AND s.expires_at > NOW()",
@@ -76,18 +68,29 @@ impl Session {
         .await
     }
 
-    pub async fn touch(pool: &PgPool, id: Uuid) -> Result<(), sqlx::Error> {
-        sqlx::query("UPDATE session SET last_seen_at = NOW() WHERE id = $1")
-            .bind(id)
-            .execute(pool)
-            .await?;
+    /// Touch `last_seen_at` AND slide `expires_at` forward by `expiry_days` from now, so
+    /// an actively-used session never hits the fixed 30-day cliff (it renews on every
+    /// authenticated request). An idle session still expires `expiry_days` after its last
+    /// activity. Keyed by token hash so the auth extractor needs no prior id lookup.
+    pub async fn touch_and_renew(
+        pool: &PgPool,
+        token_hash: &str,
+        expiry_days: i64,
+    ) -> Result<(), sqlx::Error> {
+        sqlx::query(
+            "UPDATE session
+             SET last_seen_at = NOW(),
+                 expires_at = NOW() + ($2 || ' days')::interval
+             WHERE token_hash = $1",
+        )
+        .bind(token_hash)
+        .bind(expiry_days.to_string())
+        .execute(pool)
+        .await?;
         Ok(())
     }
 
-    pub async fn delete_by_token_hash(
-        pool: &PgPool,
-        token_hash: &str,
-    ) -> Result<(), sqlx::Error> {
+    pub async fn delete_by_token_hash(pool: &PgPool, token_hash: &str) -> Result<(), sqlx::Error> {
         sqlx::query("DELETE FROM session WHERE token_hash = $1")
             .bind(token_hash)
             .execute(pool)
@@ -95,14 +98,13 @@ impl Session {
         Ok(())
     }
 
-    /// Revoke every session belonging to a user — used on ban, role change, and
-    /// PIN reset so existing JWTs stop working immediately. Returns the number
-    /// of sessions removed. Best-effort: callers log but do not fail on error.
-    pub async fn delete_by_user_id(pool: &PgPool, user_id: Uuid) -> Result<u64, sqlx::Error> {
-        let result = sqlx::query("DELETE FROM session WHERE user_id = $1")
+    /// Revoke every session for a user. Backs "sign out everywhere" and the forced
+    /// re-auth after a host PIN-reset or a ban. Returns the number of sessions cleared.
+    pub async fn delete_all_for_user(pool: &PgPool, user_id: Uuid) -> Result<u64, sqlx::Error> {
+        let r = sqlx::query("DELETE FROM session WHERE user_id = $1")
             .bind(user_id)
             .execute(pool)
             .await?;
-        Ok(result.rows_affected())
+        Ok(r.rows_affected())
     }
 }

backend/src/models/upload.rs

@@ -3,6 +3,10 @@ use serde::Serialize;
 use sqlx::PgPool;
 use uuid::Uuid;
 
+// Row shape for `upload`: every field is populated by sqlx from `RETURNING *` in `create`. Callers
+// mostly use `id` and hand the rest to the compression/feed queries, so most fields are never read
+// through this struct — they stay here so it keeps mirroring the table.
+#[allow(dead_code)]
 #[derive(Debug, sqlx::FromRow)]
 pub struct Upload {
     pub id: Uuid,
@@ -19,15 +23,6 @@ pub struct Upload {
     pub deleted_at: Option<DateTime<Utc>>,
 }
 
-/// On-disk artifact paths returned by the soft-delete methods so the caller can
-/// unlink the files after the DB commit.
-#[derive(Debug, sqlx::FromRow)]
-pub struct DeletedPaths {
-    pub original: String,
-    pub preview: Option<String>,
-    pub thumbnail: Option<String>,
-}
-
 #[derive(Debug, Serialize)]
 pub struct UploadDto {
     pub id: Uuid,
@@ -35,8 +30,6 @@ pub struct UploadDto {
     pub uploader_name: String,
     pub preview_url: Option<String>,
     pub thumbnail_url: Option<String>,
-    /// Signed gateway URL for the full-resolution original. Always present.
-    pub original_url: Option<String>,
     pub mime_type: String,
     pub caption: Option<String>,
     pub hashtags: Vec<String>,
@@ -46,10 +39,23 @@ pub struct UploadDto {
     pub created_at: DateTime<Utc>,
 }
 
+/// Minimal projection of an upload's on-disk file paths, used by the visibility-gated
+/// media aliases so they don't hydrate the entire `Upload` row per request.
+#[derive(Debug, sqlx::FromRow)]
+pub struct VisibleMedia {
+    pub original_path: String,
+    pub preview_path: Option<String>,
+    pub thumbnail_path: Option<String>,
+    pub display_path: Option<String>,
+    pub mime_type: String,
+}
+
 impl Upload {
-    /// Generic over the executor so it can run inside the upload transaction
-    /// (`&mut *tx`) alongside the quota-counter reservation, keeping the
-    /// byte-counter and the row atomic (no quota leak on a mid-write crash).
+    /// Takes any executor so the caller can run it inside a transaction (atomic
+    /// quota + insert) or standalone against the pool.
+    // Eight arguments, one per column the INSERT writes, with exactly one call site. A params
+    // struct here would restate the column list a second time and buy nothing.
+    #[allow(clippy::too_many_arguments)]
     pub async fn create<'e, E>(
         executor: E,
         event_id: Uuid,
@@ -58,13 +64,23 @@ impl Upload {
         mime_type: &str,
         original_size_bytes: i64,
         caption: Option<&str>,
-    ) -> Result<Self, sqlx::Error>
+        client_upload_id: Option<Uuid>,
+    ) -> Result<Option<Self>, sqlx::Error>
     where
         E: sqlx::PgExecutor<'e>,
     {
+        // `Ok(None)` means this exact `client_upload_id` is already stored — the caller's request
+        // is a retry of one that already succeeded, and it must replay the original row rather
+        // than create a second. Letting the unique index raise instead would work, but only after
+        // the whole transaction had aborted, and it would arrive as an opaque database error the
+        // caller would have to string-match to recognise.
+        //
+        // The conflict target repeats the index's `WHERE` clause because it is a partial index;
+        // without it Postgres cannot prove which index to use and rejects the statement.
         sqlx::query_as::<_, Self>(
-            "INSERT INTO upload (event_id, user_id, original_path, mime_type, original_size_bytes, caption)
-             VALUES ($1, $2, $3, $4, $5, $6)
+            "INSERT INTO upload (event_id, user_id, original_path, mime_type, original_size_bytes, caption, client_upload_id)
+             VALUES ($1, $2, $3, $4, $5, $6, $7)
+             ON CONFLICT (client_upload_id) WHERE client_upload_id IS NOT NULL DO NOTHING
              RETURNING *",
         )
         .bind(event_id)
@@ -73,13 +89,51 @@ impl Upload {
         .bind(mime_type)
         .bind(original_size_bytes)
         .bind(caption)
-        .fetch_one(executor)
+        .bind(client_upload_id)
+        .fetch_optional(executor)
         .await
     }
 
-    pub async fn find_by_id(pool: &PgPool, id: Uuid) -> Result<Option<Self>, sqlx::Error> {
+    /// Look up a live upload by the idempotency key its client sent.
+    ///
+    /// Scoped to the user as well as the key: the key alone is unique, but a lookup that ignored
+    /// ownership would let one guest's retry return another guest's row if a key ever repeated.
+    /// Soft-deleted rows are excluded on purpose — if the guest deleted the photo and their queue
+    /// later retries, they should get a fresh upload rather than a resurrection of a deleted one.
+    pub async fn find_by_client_upload_id(
+        pool: &sqlx::PgPool,
+        user_id: Uuid,
+        client_upload_id: Uuid,
+    ) -> Result<Option<Self>, sqlx::Error> {
         sqlx::query_as::<_, Self>(
-            "SELECT * FROM upload WHERE id = $1 AND deleted_at IS NULL",
+            "SELECT * FROM upload
+             WHERE client_upload_id = $1 AND user_id = $2 AND deleted_at IS NULL",
+        )
+        .bind(client_upload_id)
+        .bind(user_id)
+        .fetch_optional(pool)
+        .await
+    }
+
+    /// Lean lookup for the public media aliases (`get_original`/`get_preview`/
+    /// `get_thumbnail`): returns ONLY the file paths + mime for a visible upload —
+    /// excluding soft-deleted rows, hidden owners (`uploads_hidden`), and banned owners
+    /// (`is_banned`) — the same filter `v_feed` applies. So moderation that removes a post
+    /// from the feed also stops its original/preview/thumbnail from being pulled by UUID.
+    ///
+    /// Selects four columns instead of the whole `Upload` row: this runs once per image
+    /// per cache-miss on the media hot path, so we avoid hydrating fields the response
+    /// never uses.
+    pub async fn find_visible_media(
+        pool: &PgPool,
+        id: Uuid,
+    ) -> Result<Option<VisibleMedia>, sqlx::Error> {
+        sqlx::query_as::<_, VisibleMedia>(
+            "SELECT up.original_path, up.preview_path, up.thumbnail_path, up.display_path, up.mime_type
+             FROM upload up
+             JOIN \"user\" u ON u.id = up.user_id
+             WHERE up.id = $1 AND up.deleted_at IS NULL
+               AND u.uploads_hidden = false AND u.is_banned = false",
         )
         .bind(id)
         .fetch_optional(pool)
@@ -116,6 +170,82 @@ impl Upload {
         Ok(())
     }
 
+    pub async fn set_display_path(
+        pool: &PgPool,
+        id: Uuid,
+        display_path: &str,
+    ) -> Result<(), sqlx::Error> {
+        sqlx::query("UPDATE upload SET display_path = $2 WHERE id = $1")
+            .bind(id)
+            .bind(display_path)
+            .execute(pool)
+            .await?;
+        Ok(())
+    }
+
+    /// Stamp which revision of the derivative pipeline produced this row's preview/display,
+    /// so the startup backfill can find rows generated by an older one exactly once.
+    ///
+    /// Also clears the attempt counter: success is the only thing that resets it, and folding
+    /// the reset in here means both the live path and the backfill get it with no extra call
+    /// site to forget.
+    pub async fn set_derivatives_rev(pool: &PgPool, id: Uuid, rev: i16) -> Result<(), sqlx::Error> {
+        sqlx::query(
+            "UPDATE upload
+                SET derivatives_rev = $2, derivative_attempts = 0, derivative_last_error = NULL
+              WHERE id = $1",
+        )
+        .bind(id)
+        .bind(rev)
+        .execute(pool)
+        .await?;
+        Ok(())
+    }
+
+    /// Record that derivative processing is ABOUT to be attempted, returning the new count.
+    ///
+    /// WRITE-AHEAD ON PURPOSE. The failure this bounds is a cgroup SIGKILL: the process
+    /// vanishes mid-work, so no `Err` is returned, no error handler runs and no `Drop` fires.
+    /// A counter incremented after a failure would increment zero times per crash and the
+    /// boot loop would be unchanged. Counting the ATTEMPT is the only thing that survives the
+    /// process dying. The cost is that a genuinely transient failure also burns an attempt —
+    /// acceptable, because the retry budget is per-boot-loop, not per-request, and success
+    /// resets it to zero.
+    /// `None` when the row no longer exists (hard-deleted, or an e2e TRUNCATE landed while the
+    /// task waited on the semaphore) — the caller should abandon quietly rather than treat a
+    /// missing row as a processing failure.
+    pub async fn begin_derivative_attempt(
+        pool: &PgPool,
+        id: Uuid,
+    ) -> Result<Option<i16>, sqlx::Error> {
+        sqlx::query_scalar(
+            "UPDATE upload
+                SET derivative_attempts = derivative_attempts + 1
+              WHERE id = $1
+          RETURNING derivative_attempts",
+        )
+        .bind(id)
+        .fetch_optional(pool)
+        .await
+    }
+
+    /// Store why the last derivative attempt failed. Diagnostics only — nothing branches on it.
+    pub async fn record_derivative_failure(
+        pool: &PgPool,
+        id: Uuid,
+        error: &str,
+    ) -> Result<(), sqlx::Error> {
+        // Bounded: an anyhow chain can be long, and this is written on a failure path that may
+        // repeat across every row of a bad batch.
+        let truncated: String = error.chars().take(500).collect();
+        sqlx::query("UPDATE upload SET derivative_last_error = $2 WHERE id = $1")
+            .bind(id)
+            .bind(truncated)
+            .execute(pool)
+            .await?;
+        Ok(())
+    }
+
     pub async fn set_thumbnail_path(
         pool: &PgPool,
         id: Uuid,
@@ -129,65 +259,32 @@ impl Upload {
         Ok(())
     }
 
-    /// Soft-deletes the upload and decrements the uploader's `total_upload_bytes`.
-    /// Done in a single transaction so a crash between the two writes can't leave
-    /// the quota counter pointing at bytes the user has already deleted (which would
-    /// silently lock them out of future uploads).
-    ///
-    /// No-op if the row is already deleted — protects against a double-tap on the
-    /// delete action double-decrementing the counter.
-    ///
-    /// Returns the artifact paths of the row that was deleted (`None` if nothing
-    /// matched) so the caller can unlink the files after the commit.
-    pub async fn soft_delete(pool: &PgPool, id: Uuid) -> Result<Option<DeletedPaths>, sqlx::Error> {
-        let mut tx = pool.begin().await?;
-        let row: Option<(Uuid, i64, String, Option<String>, Option<String>)> = sqlx::query_as(
-            "UPDATE upload
-             SET deleted_at = NOW()
-             WHERE id = $1 AND deleted_at IS NULL
-             RETURNING user_id, original_size_bytes, original_path, preview_path, thumbnail_path",
-        )
-        .bind(id)
-        .fetch_optional(&mut *tx)
-        .await?;
-        let paths = if let Some((user_id, bytes, original, preview, thumbnail)) = row {
-            sqlx::query(
-                "UPDATE \"user\"
-                 SET total_upload_bytes = GREATEST(0, total_upload_bytes - $2)
-                 WHERE id = $1",
-            )
-            .bind(user_id)
-            .bind(bytes)
-            .execute(&mut *tx)
-            .await?;
-            Some(DeletedPaths { original, preview, thumbnail })
-        } else {
-            None
-        };
-        tx.commit().await?;
-        Ok(paths)
-    }
-
-    /// Event-scoped variant of [`Self::soft_delete`]. Returns `None` if no row
+    /// Soft-deletes an upload within its event and refunds the uploader's
+    /// `total_upload_bytes`, in one transaction. Returns `false` if no row
     /// matched (already deleted, wrong event, or unknown id) so host handlers
-    /// can return a clean 404, and the artifact paths otherwise.
+    /// can return a clean 404 instead of silently no-op'ing.
+    /// Executor-generic so a caller can run the delete and the keepsake regeneration in ONE
+    /// transaction. They must be atomic: if the delete commits and the regeneration doesn't (a
+    /// dropped handler future, a failed second tx), the taken-down photo stays in the downloadable
+    /// archive forever, and recovery can't tell — the keepsake still looks complete at the current
+    /// epoch, and the host can no longer even find the upload to retry.
     pub async fn soft_delete_in_event(
-        pool: &PgPool,
+        conn: &mut sqlx::PgConnection,
         id: Uuid,
         event_id: Uuid,
-    ) -> Result<Option<DeletedPaths>, sqlx::Error> {
-        let mut tx = pool.begin().await?;
-        let row: Option<(Uuid, i64, String, Option<String>, Option<String>)> = sqlx::query_as(
+    ) -> Result<bool, sqlx::Error> {
+        let tx = conn;
+        let row: Option<(Uuid, i64)> = sqlx::query_as(
             "UPDATE upload
              SET deleted_at = NOW()
              WHERE id = $1 AND event_id = $2 AND deleted_at IS NULL
-             RETURNING user_id, original_size_bytes, original_path, preview_path, thumbnail_path",
+             RETURNING user_id, original_size_bytes",
         )
         .bind(id)
         .bind(event_id)
         .fetch_optional(&mut *tx)
         .await?;
-        let paths = if let Some((user_id, bytes, original, preview, thumbnail)) = row {
+        let deleted = if let Some((user_id, bytes)) = row {
             sqlx::query(
                 "UPDATE \"user\"
                  SET total_upload_bytes = GREATEST(0, total_upload_bytes - $2)
@@ -197,23 +294,25 @@ impl Upload {
             .bind(bytes)
             .execute(&mut *tx)
             .await?;
-            Some(DeletedPaths { original, preview, thumbnail })
+            true
         } else {
-            None
+            false
         };
-        tx.commit().await?;
-        Ok(paths)
+        Ok(deleted)
     }
 
-    pub async fn update_caption(
-        pool: &PgPool,
+    pub async fn update_caption<'e, E>(
+        executor: E,
         id: Uuid,
         caption: Option<&str>,
-    ) -> Result<(), sqlx::Error> {
+    ) -> Result<(), sqlx::Error>
+    where
+        E: sqlx::PgExecutor<'e>,
+    {
         sqlx::query("UPDATE upload SET caption = $2 WHERE id = $1")
             .bind(id)
             .bind(caption)
-            .execute(pool)
+            .execute(executor)
             .await?;
         Ok(())
     }

backend/src/models/user.rs

@@ -22,6 +22,10 @@ impl UserRole {
     }
 }
 
+// Row shape for `user`: every field is populated by sqlx from `SELECT *` / `RETURNING *`.
+// `uploads_hidden`, `failed_pin_attempts` and `created_at` are enforced/updated in SQL rather than
+// read in Rust, but they are part of the row and stay here so the struct keeps mirroring the table.
+#[allow(dead_code)]
 #[derive(Debug, sqlx::FromRow)]
 pub struct User {
     pub id: Uuid,
@@ -56,6 +60,54 @@ impl User {
         .await
     }
 
+    /// Create a user with an explicit role, in ONE statement.
+    ///
+    /// `create` + a separate `UPDATE ... SET role` is not equivalent: a crash or a pool error
+    /// between the two leaves a GUEST row holding a reserved name, which is exactly the
+    /// poisoned state that bricked admin login — now self-inflicted, and invisible to a
+    /// role-based lookup, so the next login would create yet another.
+    pub async fn create_with_role(
+        pool: &PgPool,
+        event_id: Uuid,
+        display_name: &str,
+        pin_hash: &str,
+        role: UserRole,
+    ) -> Result<Self, sqlx::Error> {
+        sqlx::query_as::<_, Self>(
+            "INSERT INTO \"user\" (event_id, display_name, recovery_pin_hash, role)
+             VALUES ($1, $2, $3, $4)
+             RETURNING *",
+        )
+        .bind(event_id)
+        .bind(display_name)
+        .bind(pin_hash)
+        .bind(role)
+        .fetch_one(pool)
+        .await
+    }
+
+    /// The event's admin, looked up BY ROLE.
+    ///
+    /// The name is not the identity and never was. Looking the admin up by `display_name`
+    /// meant any guest who joined as "Admin" first made the lookup miss, and the fallback
+    /// `create` then violated the case-insensitive unique index from migration 007 — a
+    /// permanent 500 on admin login, recoverable only by hand-editing the database.
+    ///
+    /// `ORDER BY created_at` so a database that somehow acquired two admin rows resolves to a
+    /// stable one rather than alternating between them.
+    pub async fn find_admin_for_event(
+        pool: &PgPool,
+        event_id: Uuid,
+    ) -> Result<Option<Self>, sqlx::Error> {
+        sqlx::query_as::<_, Self>(
+            "SELECT * FROM \"user\" WHERE event_id = $1 AND role = 'admin'
+             ORDER BY created_at ASC LIMIT 1",
+        )
+        .bind(event_id)
+        .fetch_optional(pool)
+        .await
+    }
+
     pub async fn find_by_id(pool: &PgPool, id: Uuid) -> Result<Option<Self>, sqlx::Error> {
         sqlx::query_as::<_, Self>("SELECT * FROM \"user\" WHERE id = $1")
             .bind(id)
@@ -92,33 +144,54 @@ impl User {
         Ok(row.0)
     }
 
+    /// Window after which a failed-PIN streak is forgotten. Matches the lockout duration, so
+    /// "wait out the cooldown" and "start clean" are the same interval to a guest.
+    const PIN_ATTEMPT_DECAY_MINUTES: i64 = 15;
+
+    /// Record a wrong PIN and return the CURRENT streak length.
+    ///
+    /// The counter decays: before this, it only ever cleared on a successful recovery or after
+    /// a lockout expired, so ordinary typos accumulated across days and a guest could arrive at
+    /// an event already most of the way to being locked out by mistakes made the night before.
+    /// Decay is what makes the raised lock threshold safe rather than merely lenient.
     pub async fn increment_failed_pin(pool: &PgPool, id: Uuid) -> Result<i16, sqlx::Error> {
         let row: (i16,) = sqlx::query_as(
             "UPDATE \"user\"
-             SET failed_pin_attempts = failed_pin_attempts + 1
+             SET failed_pin_attempts = CASE
+                     WHEN last_failed_pin_at IS NULL
+                       OR last_failed_pin_at < NOW() - ($2 || ' minutes')::interval
+                     THEN 1
+                     ELSE failed_pin_attempts + 1
+                 END,
+                 last_failed_pin_at = NOW()
              WHERE id = $1
              RETURNING failed_pin_attempts",
         )
         .bind(id)
+        .bind(Self::PIN_ATTEMPT_DECAY_MINUTES.to_string())
         .fetch_one(pool)
         .await?;
         Ok(row.0)
     }
 
-    pub async fn lock_pin(pool: &PgPool, id: Uuid, until: DateTime<Utc>) -> Result<(), sqlx::Error> {
-        sqlx::query(
-            "UPDATE \"user\" SET pin_locked_until = $2 WHERE id = $1",
-        )
-        .bind(id)
-        .bind(until)
-        .execute(pool)
-        .await?;
+    pub async fn lock_pin(
+        pool: &PgPool,
+        id: Uuid,
+        until: DateTime<Utc>,
+    ) -> Result<(), sqlx::Error> {
+        sqlx::query("UPDATE \"user\" SET pin_locked_until = $2 WHERE id = $1")
+            .bind(id)
+            .bind(until)
+            .execute(pool)
+            .await?;
         Ok(())
     }
 
     pub async fn reset_pin_attempts(pool: &PgPool, id: Uuid) -> Result<(), sqlx::Error> {
         sqlx::query(
-            "UPDATE \"user\" SET failed_pin_attempts = 0, pin_locked_until = NULL WHERE id = $1",
+            "UPDATE \"user\"
+                SET failed_pin_attempts = 0, pin_locked_until = NULL, last_failed_pin_at = NULL
+              WHERE id = $1",
         )
         .bind(id)
         .execute(pool)

backend/src/services/compression.rs

@@ -1,9 +1,10 @@
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
 
 use anyhow::{Context, Result};
 use sqlx::PgPool;
-use tokio::sync::{broadcast, Semaphore};
+use tokio::sync::{Semaphore, broadcast};
 use uuid::Uuid;
 
 use crate::models::upload::Upload;
@@ -11,41 +12,116 @@ use crate::state::SseEvent;
 
 #[derive(Clone)]
 pub struct CompressionWorker {
-    /// Separate permit pools for images and videos so a couple of slow/large
-    /// videos (each holding a permit across the full ffmpeg wait) can never
-    /// starve image-preview generation, and vice versa.
-    image_sem: Arc<Semaphore>,
-    video_sem: Arc<Semaphore>,
+    semaphore: Arc<Semaphore>,
     pool: PgPool,
     media_path: PathBuf,
     sse_tx: broadcast::Sender<SseEvent>,
+    /// Bumped whenever the underlying data is reset out from under in-flight work (only the e2e
+    /// TRUNCATE does this today). A task captures the value at spawn and abandons itself if it has
+    /// changed by the time it runs — see `process`.
+    generation: Arc<AtomicU64>,
 }
 
 impl CompressionWorker {
     pub fn new(
         pool: PgPool,
         media_path: PathBuf,
-        image_concurrency: usize,
-        video_concurrency: usize,
+        concurrency: usize,
         sse_tx: broadcast::Sender<SseEvent>,
     ) -> Self {
         Self {
-            image_sem: Arc::new(Semaphore::new(image_concurrency)),
-            video_sem: Arc::new(Semaphore::new(video_concurrency)),
+            semaphore: Arc::new(Semaphore::new(concurrency)),
             pool,
             media_path,
             sse_tx,
+            generation: Arc::new(AtomicU64::new(0)),
         }
     }
 
+    /// Invalidate all in-flight and queued compression work. Called by the e2e TRUNCATE endpoint:
+    /// truncating deletes the upload rows and wipes `media/`, so a worker that was queued on the
+    /// semaphore when the wipe happened would otherwise wake in the NEXT test, fail to find its
+    /// file, and broadcast `upload-error` / `upload-deleted` into that test's live SSE stream —
+    /// corrupting any test that asserts on toasts or feed contents. Bumping the generation makes
+    /// those stale tasks return silently instead. A no-op in production (never called there).
+    pub fn bump_generation(&self) {
+        self.generation.fetch_add(1, Ordering::SeqCst);
+    }
+
+    /// How many times `do_process` is attempted before an upload is given up on. The
+    /// give-up path is user-visible (the photo disappears), so transient infrastructure
+    /// errors must not reach it.
+    const MAX_PROCESS_ATTEMPTS: u32 = 3;
+
+    /// Revision of the image-derivative pipeline. Bump this whenever a change makes existing
+    /// previews/displays wrong, so `backfill_stale_derivatives` regenerates them once on the
+    /// next start. Rev 1 = EXIF orientation is applied.
+    const DERIVATIVES_REV: i16 = 1;
+
+    /// How many times derivative generation may be ATTEMPTED for one upload before it is left
+    /// alone. Counted write-ahead and reset on success — see `Upload::begin_derivative_attempt`.
+    ///
+    /// This is what turns a fatal input from an outage into a blemish. The startup backfill
+    /// runs unconditionally on every boot, so before this bound a row whose processing killed
+    /// the process was re-selected and re-run forever, and `restart: unless-stopped` made that
+    /// an infinite loop that also dropped every SSE stream and truncated every in-flight
+    /// upload on each cycle. Three attempts absorbs genuinely transient infrastructure
+    /// failures (an ENOSPC spike, a pool blip) without ever becoming unbounded.
+    const MAX_DERIVATIVE_ATTEMPTS: i16 = 3;
+
+    /// Rows regenerated per boot. Bounds both the query and the amount of work a single start
+    /// can queue; whatever is left is picked up on the next boot.
+    const BACKFILL_BATCH: i64 = 200;
+
     /// Spawn a background task to process an uploaded file.
     pub fn process(&self, upload_id: Uuid, original_path: String, mime_type: String) {
         let worker = self.clone();
+        let born_at = worker.generation.load(Ordering::SeqCst);
         tokio::spawn(async move {
-            let is_video = mime_type.starts_with("video/");
-            let sem = if is_video { &worker.video_sem } else { &worker.image_sem };
-            let _permit = sem.acquire().await;
-            match worker.do_process(upload_id, &original_path, &mime_type).await {
+            let _permit = worker.semaphore.acquire().await;
+            // The data this task was queued against may have been reset while it waited for a permit
+            // (e2e TRUNCATE). If so, its file and row are gone; doing anything — including
+            // broadcasting a failure — would leak into an unrelated test. Abandon quietly.
+            if worker.generation.load(Ordering::SeqCst) != born_at {
+                return;
+            }
+            // Retry before giving up. Most failures here are transient and self-clearing —
+            // an ENOSPC spike while several guests upload at once, a momentary DB-pool
+            // exhaustion, a panic inside the image codec — and the give-up path is
+            // user-visible data loss, so it is worth a few seconds to avoid entering it.
+            //
+            // But only for failures that CAN clear. An image that exceeds the decode budget,
+            // is corrupt, or is in an unsupported format fails identically on every attempt,
+            // so retrying it just burns 2s + 4s of backoff and writes three near-identical
+            // warnings before reaching the same conclusion. Give up on those immediately.
+            let mut attempt = 1u32;
+            let outcome = loop {
+                match worker
+                    .do_process(upload_id, &original_path, &mime_type)
+                    .await
+                {
+                    Ok(v) => break Ok(v),
+                    Err(e)
+                        if attempt < Self::MAX_PROCESS_ATTEMPTS
+                            && !crate::services::imaging::is_permanent_image_error(&e)
+                            && !crate::services::imaging::is_storage_full_error(&e) =>
+                    {
+                        tracing::warn!(
+                            error = ?e, %upload_id, attempt,
+                            "compression attempt failed; retrying"
+                        );
+                        tokio::time::sleep(std::time::Duration::from_secs(2u64.pow(attempt))).await;
+                        attempt += 1;
+                        // The data may have been reset while we slept (e2e TRUNCATE).
+                        if worker.generation.load(Ordering::SeqCst) != born_at {
+                            return;
+                        }
+                    }
+                    Err(e) => break Err(e),
+                }
+            };
+
+            match outcome {
                 Ok(_) => {
                     tracing::info!("compression completed for upload {upload_id}");
                     let _ = worker.sse_tx.send(SseEvent {
@@ -53,19 +129,77 @@ impl CompressionWorker {
                         data: serde_json::json!({ "upload_id": upload_id }).to_string(),
                     });
                 }
+                Err(e) if crate::services::imaging::is_storage_full_error(&e) => {
+                    // Out of disk. Keep the row AND the original — the opposite of the branch
+                    // below, and for the same reason it retains the file: nothing here is the
+                    // guest's fault and nothing about the photo is wrong.
+                    //
+                    // Soft-deleting on ENOSPC was strictly harmful. It refunded the quota while
+                    // keeping the bytes, so it freed nothing, removed the photo from the feed
+                    // seconds after a `201 Created`, and handed the guest the allowance to
+                    // upload it again into the same full disk. Leaving the row live costs
+                    // nothing instead: every client already falls back to the original when
+                    // `preview_url` and `thumbnail_url` are NULL, so the photo stays visible —
+                    // just uncompressed — and `backfill_stale_derivatives` regenerates the
+                    // derivatives on the next start, once there is room for them.
+                    tracing::error!(
+                        %upload_id,
+                        "compression failed: the media filesystem is out of space. The upload is \
+                         kept and served from its original; free disk space and restart to \
+                         regenerate derivatives: {e:#}"
+                    );
+                    let _ = Upload::set_compression_status(&worker.pool, upload_id, "failed").await;
+                    // Not an "error" event: nothing was lost and there is nothing for the guest
+                    // to act on. Clients treat this purely as "refetch me", which is what makes
+                    // the card appear with its original as the image source.
+                    let _ = worker.sse_tx.send(SseEvent {
+                        event_type: "upload-processed".to_string(),
+                        data: serde_json::json!({ "upload_id": upload_id }).to_string(),
+                    });
+                }
                 Err(e) => {
-                    // Log the detailed error (incl. paths) server-side only; the
-                    // SSE channel is broadcast to every client, so send a generic
-                    // message — never leak absolute filesystem paths.
-                    tracing::error!("compression failed for upload {upload_id}: {e:#}");
+                    tracing::error!(
+                        "compression failed for upload {upload_id} after {attempt} attempt(s): {e:#}"
+                    );
+                    // KEEP THE ROW. This used to soft-delete, which made a derivative failure
+                    // indistinguishable — to the guest — from their photo being deleted: they
+                    // got a `201 Created`, watched the card appear, and then watched it vanish.
+                    // The row left `v_feed`, `find_visible_media` and BOTH keepsake archives,
+                    // so the photo was gone from the product's core promise while its bytes sat
+                    // on disk for 14 days waiting for a `cleanup_deleted_media` that nothing
+                    // told anyone about. There is no host or admin screen listing compression
+                    // failures, so recovery meant hand-written SQL that also had to re-add the
+                    // refunded quota bytes. Against "0 lost uploads", that was silent per-photo
+                    // loss on any error the ENOSPC arm above doesn't catch — a HEIC that slipped
+                    // the allowlist, a truncated frame, an ffmpeg hiccup, a pool blip.
+                    //
+                    // This is exactly what the ENOSPC arm already does and documents as correct:
+                    // every client falls back to the original when `preview_url` and
+                    // `thumbnail_url` are NULL, so the photo stays visible and downloadable —
+                    // just uncompressed — and `backfill_stale_derivatives` retries it on the
+                    // next boot, now bounded by `derivative_attempts` so a poisoned row cannot
+                    // loop. The quota stays charged, which is correct: the bytes are still on
+                    // disk and still the guest's.
+                    let _ = Upload::set_compression_status(&worker.pool, upload_id, "failed").await;
+                    tracing::warn!(
+                        %upload_id,
+                        path = %worker.media_path.join(&original_path).display(),
+                        "derivatives failed; the upload is kept and served from its original"
+                    );
+                    // `upload-error` still fires so the uploader learns the photo will look
+                    // uncompressed. `upload-deleted` deliberately does NOT — nothing was
+                    // deleted, and evicting the card was the visible half of the data loss.
                     let _ = worker.sse_tx.send(SseEvent {
                         event_type: "upload-error".to_string(),
-                        data: serde_json::json!({
-                            "upload_id": upload_id,
-                            "error": "Verarbeitung fehlgeschlagen."
-                        }).to_string(),
+                        data: serde_json::json!({ "upload_id": upload_id, "error": e.to_string() })
+                            .to_string(),
+                    });
+                    // Tell every client to refetch, so the card re-renders from the original
+                    // instead of sitting on a stale "processing" placeholder forever.
+                    let _ = worker.sse_tx.send(SseEvent {
+                        event_type: "upload-processed".to_string(),
+                        data: serde_json::json!({ "upload_id": upload_id }).to_string(),
                     });
-                    let _ = Upload::set_compression_status(&worker.pool, upload_id, "failed").await;
                 }
             }
         });
@@ -82,143 +216,632 @@ impl CompressionWorker {
         let original = self.media_path.join(original_path);
 
         if mime_type.starts_with("image/") {
-            let preview_rel = self.generate_image_preview(upload_id, &original, mime_type).await?;
+            // Count the attempt BEFORE doing the work — see `begin_derivative_attempt`. If this
+            // input is the one that kills the container, this write is the only record that
+            // survives, and it is what stops the boot backfill replaying it forever.
+            match Upload::begin_derivative_attempt(&self.pool, upload_id).await? {
+                Some(attempts) if attempts > Self::MAX_DERIVATIVE_ATTEMPTS => {
+                    anyhow::bail!(
+                        "derivative generation gave up after {} attempt(s)",
+                        attempts - 1
+                    );
+                }
+                Some(_) => {}
+                // The row vanished while this task waited on the semaphore. Nothing to do, and
+                // reporting a failure would broadcast into a stream that no longer has a card.
+                None => return Ok(()),
+            }
+            let (preview_rel, display_rel) = self
+                .generate_image_derivatives(upload_id, &original, mime_type)
+                .await?;
             Upload::set_preview_path(&self.pool, upload_id, &preview_rel).await?;
-            tracing::info!("preview generated for upload {upload_id}");
+            Upload::set_display_path(&self.pool, upload_id, &display_rel).await?;
+            Upload::set_derivatives_rev(&self.pool, upload_id, Self::DERIVATIVES_REV).await?;
+            tracing::info!("preview + display generated for upload {upload_id}");
         } else if mime_type.starts_with("video/") {
-            let thumb_rel = self.generate_video_thumbnail(upload_id, &original).await?;
-            Upload::set_thumbnail_path(&self.pool, upload_id, &thumb_rel).await?;
-            tracing::info!("thumbnail generated for upload {upload_id}");
+            // A missing poster must NOT fail the upload. `set_thumbnail_path` is only reached when
+            // a file really exists, so `thumbnail_path` stays NULL otherwise — which every consumer
+            // already handles (FeedListCard, VirtualFeed, LightboxModal are all null-safe).
+            //
+            // The `?` here used to hide the defect; making the check strict without also making
+            // this non-fatal would have been far worse than the bug. Every clip of a second or less
+            // would fail compression, exhaust its retries and be soft-deleted — a cosmetic defect
+            // turned into data loss, on exactly the mis-tap/Live-Photo clips guests produce most.
+            // Handling only the `Ok(None)` arm was not enough: the `?` on the call itself still
+            // routed every OTHER poster failure into the give-up path. `extract_poster_frame`
+            // returns `Err` when ffmpeg is missing from the image, when it hangs on a truncated
+            // `.mov` and trips FFMPEG_TIMEOUT, or when `thumbnails/` can't be created — and
+            // `set_thumbnail_path` returns `Err` on any DB blip. None of those say anything about
+            // the video itself, yet each one destroyed it. Confirmed live: on a box with no ffmpeg
+            // the spawn error propagated, exhausted all three attempts and soft-deleted the clip.
+            //
+            // Nothing about a video post depends on the poster — `get_original` serves the file
+            // byte-for-byte and the tile falls back to the video element — so no failure in this
+            // branch may fail the upload.
+            match self.generate_video_thumbnail(upload_id, &original).await {
+                Ok(Some(thumb_rel)) => {
+                    match Upload::set_thumbnail_path(&self.pool, upload_id, &thumb_rel).await {
+                        Ok(()) => tracing::info!("thumbnail generated for upload {upload_id}"),
+                        Err(e) => tracing::warn!(
+                            error = ?e, %upload_id,
+                            "poster extracted but could not be recorded; the video keeps its own tile"
+                        ),
+                    }
+                }
+                Ok(None) => {
+                    tracing::warn!(
+                        %upload_id,
+                        "no poster frame could be extracted; the video keeps its own tile"
+                    );
+                }
+                Err(e) => {
+                    tracing::warn!(
+                        error = ?e, %upload_id,
+                        "poster extraction failed; the video keeps its own tile"
+                    );
+                }
+            }
         }
 
         Upload::set_compression_status(&self.pool, upload_id, "done").await?;
         Ok(())
     }
 
-    async fn generate_image_preview(
+    /// Longest edge of the big-screen "display" derivative used by the diashow. Sized to be
+    /// sharp on 1080p/4K while staying bounded (a ~2048px JPEG decodes to ~16 MB — trivial
+    /// for any kiosk, unlike a raw multi-thousand-pixel original).
+    const DISPLAY_MAX_EDGE: u32 = 2048;
+    /// Longest edge of the phone-feed "preview" (data-saver default).
+    const PREVIEW_MAX_EDGE: u32 = 800;
+
+    /// Above this pixel count the PNG original is stored as uploaded, unoptimised.
+    ///
+    /// oxipng's peak memory scales with PIXELS, not file size: it decodes the PNG itself and
+    /// then evaluates row filters, each trial holding a full-size buffer. That is why a 2.82
+    /// MiB file could measure 1250 MiB of peak RSS inside a 1 GiB container — smooth,
+    /// synthetic content compresses to almost nothing on disk while still being 8000x8000.
+    /// 8 MP covers every real phone photo; beyond it we decline the (lossless, cosmetic)
+    /// saving rather than risk the OOM kill.
+    const OXIPNG_MAX_PIXELS: u64 = 8_000_000;
+
+
+    /// Wall-clock ceiling for one oxipng run.
+    ///
+    /// Bounds TIME, NOT MEMORY — oxipng checks the deadline between trials, so a single trial
+    /// still allocates in full. The pixel gate above and the sequential build (see
+    /// `default-features = false` in Cargo.toml) are what bound memory. Do not treat this
+    /// constant as the OOM fix.
+    const OXIPNG_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(20);
+
+    /// Decode the image ONCE and emit both derivatives — the 800px `preview` (phone feed)
+    /// and the 2048px `display` (diashow). Returns `(preview_rel, display_rel)`.
+    async fn generate_image_derivatives(
         &self,
         upload_id: Uuid,
         original: &Path,
         mime_type: &str,
-    ) -> Result<String> {
+    ) -> Result<(String, String)> {
         let previews_dir = self.media_path.join("previews");
+        let displays_dir = self.media_path.join("displays");
         tokio::fs::create_dir_all(&previews_dir).await?;
+        tokio::fs::create_dir_all(&displays_dir).await?;
 
-        let preview_filename = format!("{upload_id}.jpg");
-        let preview_path = previews_dir.join(&preview_filename);
+        let filename = format!("{upload_id}.jpg");
+        let preview_path = previews_dir.join(&filename);
+        let display_path = displays_dir.join(&filename);
         let original = original.to_path_buf();
-        let preview_path_clone = preview_path.clone();
         let mime_owned = mime_type.to_string();
 
-        // Run blocking image operations in a spawn_blocking task, bounded by a
-        // hard timeout (mirrors the ffmpeg guard) so a pathological decode can't
-        // hold the permit forever.
-        let handle = tokio::task::spawn_blocking(move || -> Result<()> {
-            use image::ImageReader;
-
-            // Reject decompression bombs *before* fully decoding: a small file can
-            // otherwise expand to enormous dimensions and a very expensive resize.
-            // 12000×12000 covers any real phone photo; max_alloc caps memory.
-            let mut reader = ImageReader::open(&original)
-                .context("failed to open image")?
-                .with_guessed_format()
-                .context("failed to read image header")?;
-            let mut limits = image::Limits::default();
-            limits.max_image_width = Some(12_000);
-            limits.max_image_height = Some(12_000);
-            limits.max_alloc = Some(256 * 1024 * 1024);
-            reader.limits(limits);
-            let img = reader.decode().context("failed to decode image")?;
-
-            // Resize to max 800px wide, preserving aspect ratio
-            let preview = img.resize(800, 800, image::imageops::FilterType::Lanczos3);
-            preview.save_with_format(&preview_path_clone, image::ImageFormat::Jpeg)
-                .context("failed to save preview")?;
-
-            // If the original is PNG, try lossless compression in-place
-            if mime_owned == "image/png" {
-                let opts = oxipng::Options::from_preset(2);
-                let _ = oxipng::optimize(
-                    &oxipng::InFile::Path(original),
-                    &oxipng::OutFile::Path {
-                        path: None,
-                        preserve_attrs: true,
-                    },
-                    &opts,
+        // Estimate the peak from the HEADER (no pixels decoded — the same kind of cheap probe
+        // the upload handler already does via `exceeds_decode_budget`) and, if this job is a
+        // giant, take the exclusive permit so it cannot overlap another giant. Held for the
+        // whole blocking section, released on drop including on error.
+        let estimate =
+            crate::services::imaging::estimated_processing_peak_bytes(&original, Self::DISPLAY_MAX_EDGE);
+        let _heavy_permit = match estimate {
+            Some(bytes) if bytes > crate::services::imaging::HEAVY_IMAGE_BYTES => {
+                tracing::debug!(
+                    %upload_id,
+                    estimated_mib = bytes / (1024 * 1024),
+                    "waiting for the heavy-image permit"
                 );
+                Some(crate::services::imaging::HEAVY_IMAGE_PERMITS.acquire().await)
             }
+            _ => None,
+        };
 
-            Ok(())
-        });
+        // Run blocking image operations in a spawn_blocking task
+        tokio::task::spawn_blocking(move || {
+            write_image_derivatives(upload_id, &original, &mime_owned, &preview_path, &display_path)
+        })
+        .await??;
 
-        match tokio::time::timeout(std::time::Duration::from_secs(120), handle).await {
-            Ok(join) => join.context("image task panicked")??,
-            Err(_) => anyhow::bail!("image processing timeout after 120s"),
-        }
-
-        Ok(format!("previews/{preview_filename}"))
+        Ok((
+            format!("previews/{filename}"),
+            format!("displays/{filename}"),
+        ))
     }
 
+    /// Regenerate image derivatives that an older pipeline produced. Fire-and-forget from
+    /// startup; picks up two cases, both of which leave the ORIGINAL untouched:
+    ///
+    /// - uploads processed before the `display` derivative existed (preview but no
+    ///   `display_path`), and
+    /// - uploads whose derivatives predate `DERIVATIVES_REV` — currently rev 1, which applies
+    ///   the EXIF orientation. Everything generated before it is stored sideways for any
+    ///   portrait phone photo.
+    ///
+    /// Unlike the failure path in `process`, a backfill error is logged and skipped — it must
+    /// NEVER destroy or soft-delete an upload that already has a working preview.
+    ///
+    /// Bounded in three ways, all of them load-bearing on a box that restarts itself:
+    /// `derivative_attempts` stops a fatal row being replayed on every boot, `BACKFILL_BATCH`
+    /// stops one start queueing unbounded work, and the whole thing runs as ONE task walking
+    /// the rows sequentially rather than N tasks racing for the same semaphore.
+    pub async fn backfill_stale_derivatives(&self) {
+        // `original_path IS NOT NULL` was dead — the column is NOT NULL. What actually needs
+        // excluding is the blanked path `cleanup_deleted_media` leaves behind.
+        let rows = sqlx::query_as::<_, (Uuid, String, String)>(
+            "SELECT id, original_path, mime_type FROM upload
+             WHERE deleted_at IS NULL AND mime_type LIKE 'image/%'
+               AND original_path <> ''
+               AND derivative_attempts < $2
+               AND (
+                     (display_path IS NULL AND preview_path IS NOT NULL)
+                  OR derivatives_rev < $1
+               )
+             ORDER BY created_at DESC
+             LIMIT $3",
+        )
+        .bind(Self::DERIVATIVES_REV)
+        .bind(Self::MAX_DERIVATIVE_ATTEMPTS)
+        .bind(Self::BACKFILL_BATCH)
+        .fetch_all(&self.pool)
+        .await;
+        let rows = match rows {
+            Ok(r) => r,
+            Err(e) => {
+                tracing::warn!(error = ?e, "derivative backfill query failed");
+                return;
+            }
+        };
+
+        self.report_exhausted_derivatives().await;
+
+        if rows.is_empty() {
+            return;
+        }
+        tracing::info!("regenerating derivatives for {} upload(s)", rows.len());
+
+        // ONE task for the whole batch. The previous shape spawned a task per row, so a large
+        // backlog created thousands of live tasks that each held a pool handle and queued on
+        // the same two semaphore permits, competing with live uploads for the entire boot.
+        let worker = self.clone();
+        tokio::spawn(async move {
+            for (id, original_path, mime_type) in rows {
+                let _permit = worker.semaphore.acquire().await;
+                // Write-ahead, exactly as in the live path: if this row is the one that kills
+                // the process, this increment is the only thing that outlives the SIGKILL.
+                match Upload::begin_derivative_attempt(&worker.pool, id).await {
+                    Ok(Some(n)) if n > Self::MAX_DERIVATIVE_ATTEMPTS => continue,
+                    Ok(Some(_)) => {}
+                    Ok(None) => continue,
+                    Err(e) => {
+                        tracing::warn!(error = ?e, %id, "could not record a backfill attempt; skipping");
+                        continue;
+                    }
+                }
+                let original = worker.media_path.join(&original_path);
+                match worker
+                    .generate_image_derivatives(id, &original, &mime_type)
+                    .await
+                {
+                    Ok((preview_rel, display_rel)) => {
+                        let _ = Upload::set_preview_path(&worker.pool, id, &preview_rel).await;
+                        let _ = Upload::set_display_path(&worker.pool, id, &display_rel).await;
+                        // Clears derivative_attempts too, so a row that failed transiently is
+                        // not one boot closer to being abandoned.
+                        let _ =
+                            Upload::set_derivatives_rev(&worker.pool, id, Self::DERIVATIVES_REV)
+                                .await;
+                        tracing::info!("derivatives regenerated for upload {id}");
+                    }
+                    Err(e) => {
+                        // Leave the existing derivatives and the original intact; this row is
+                        // retried on the next start until its attempt budget runs out. The rev
+                        // stays behind, which is the marker that it still needs doing.
+                        tracing::warn!(error = ?e, %id, "derivative backfill failed; leaving as-is");
+                        let _ =
+                            Upload::record_derivative_failure(&worker.pool, id, &format!("{e:#}"))
+                                .await;
+                    }
+                }
+            }
+        });
+    }
+
+    /// Re-extract poster frames for videos that never got one.
+    ///
+    /// A video interrupted by a restart is stranded: `startup_recovery` flips its
+    /// `compression_status` from `processing` to `failed` and nothing re-enqueues it, so
+    /// `thumbnail_path` stays NULL forever while the clip itself plays fine. The feed shows a
+    /// posterless tile for the rest of the event, and after
+    /// `FAILED_ORIGINAL_RETENTION_DAYS` the reclaim sweep is entitled to the original.
+    ///
+    /// Shares `derivative_attempts` with the image backfill on purpose. Note the consequence,
+    /// which is intended rather than a bug to fix later: `extract_poster_frame` returning
+    /// `Ok(false)` is a NORMAL, permanent outcome for a sub-second clip (Live Photos,
+    /// mis-taps), and since the counter is write-ahead and only cleared by a real success,
+    /// those clips stop being re-ffmpeg'd on every boot once the budget is spent.
+    pub async fn backfill_video_posters(&self) {
+        let rows = sqlx::query_as::<_, (Uuid, String)>(
+            "SELECT id, original_path FROM upload
+             WHERE deleted_at IS NULL AND mime_type LIKE 'video/%'
+               AND thumbnail_path IS NULL
+               AND original_path <> ''
+               AND derivative_attempts < $1
+             ORDER BY created_at DESC
+             LIMIT $2",
+        )
+        .bind(Self::MAX_DERIVATIVE_ATTEMPTS)
+        .bind(Self::BACKFILL_BATCH)
+        .fetch_all(&self.pool)
+        .await;
+        let rows = match rows {
+            Ok(r) => r,
+            Err(e) => {
+                tracing::warn!(error = ?e, "video poster backfill query failed");
+                return;
+            }
+        };
+        if rows.is_empty() {
+            return;
+        }
+        tracing::info!("re-extracting posters for {} video(s)", rows.len());
+
+        let worker = self.clone();
+        tokio::spawn(async move {
+            for (id, original_path) in rows {
+                let _permit = worker.semaphore.acquire().await;
+                match Upload::begin_derivative_attempt(&worker.pool, id).await {
+                    Ok(Some(n)) if n > Self::MAX_DERIVATIVE_ATTEMPTS => continue,
+                    Ok(Some(_)) => {}
+                    Ok(None) => continue,
+                    Err(e) => {
+                        tracing::warn!(error = ?e, %id, "could not record a poster attempt; skipping");
+                        continue;
+                    }
+                }
+                let original = worker.media_path.join(&original_path);
+                match worker.generate_video_thumbnail(id, &original).await {
+                    Ok(Some(thumb_rel)) => {
+                        if Upload::set_thumbnail_path(&worker.pool, id, &thumb_rel)
+                            .await
+                            .is_ok()
+                        {
+                            // Clears the attempt counter: a video that eventually succeeded
+                            // must not carry a budget scar into a future pipeline revision.
+                            let _ = Upload::set_derivatives_rev(
+                                &worker.pool,
+                                id,
+                                Self::DERIVATIVES_REV,
+                            )
+                            .await;
+                            tracing::info!("poster regenerated for upload {id}");
+                        }
+                    }
+                    // No frame at all — normal for a very short clip. The tile stays
+                    // posterless and the attempt is spent, which is what stops the retry.
+                    Ok(None) => {
+                        tracing::debug!(%id, "still no poster frame; leaving the tile as-is");
+                    }
+                    Err(e) => {
+                        tracing::warn!(error = ?e, %id, "poster backfill failed; leaving as-is");
+                        let _ =
+                            Upload::record_derivative_failure(&worker.pool, id, &format!("{e:#}"))
+                                .await;
+                    }
+                }
+            }
+        });
+    }
+
+    /// Say out loud, once per boot, that some uploads have stopped being retried.
+    ///
+    /// Without this the give-up is invisible: the loop stops (which is the point) but the
+    /// affected photos keep a stale or missing derivative forever with nothing to notice. The
+    /// originals are untouched, so this is recoverable once the cause is fixed — reset
+    /// `derivative_attempts` to 0 and restart.
+    async fn report_exhausted_derivatives(&self) {
+        let exhausted: Result<i64, _> = sqlx::query_scalar(
+            "SELECT count(*) FROM upload
+             WHERE deleted_at IS NULL AND mime_type LIKE 'image/%'
+               AND derivative_attempts >= $2
+               AND (
+                     (display_path IS NULL AND preview_path IS NOT NULL)
+                  OR derivatives_rev < $1
+               )",
+        )
+        .bind(Self::DERIVATIVES_REV)
+        .bind(Self::MAX_DERIVATIVE_ATTEMPTS)
+        .fetch_one(&self.pool)
+        .await;
+        if let Ok(count) = exhausted
+            && count > 0
+        {
+            tracing::error!(
+                count,
+                "{count} upload(s) exhausted derivative regeneration and will no longer be \
+                 retried; their originals are intact — see upload.derivative_last_error, fix \
+                 the cause, then reset derivative_attempts to 0 and restart"
+            );
+        }
+    }
+
+    /// Extract the feed poster for a video. `Ok(None)` when the clip yields no frame — see
+    /// [`crate::services::video::extract_poster_frame`], which owns the seek order, the timeout and
+    /// the artifact check that this function used to be missing.
     async fn generate_video_thumbnail(
         &self,
         upload_id: Uuid,
         original: &Path,
-    ) -> Result<String> {
+    ) -> Result<Option<String>> {
         let thumbs_dir = self.media_path.join("thumbnails");
         tokio::fs::create_dir_all(&thumbs_dir).await?;
 
         let thumb_filename = format!("{upload_id}.jpg");
         let thumb_path = thumbs_dir.join(&thumb_filename);
 
-        // Hard timeout — a malformed video can hang `ffmpeg` indefinitely. Without a
-        // cap, the held compression-worker semaphore permit is never released and the
-        // pool eventually deadlocks (no further uploads ever processed). 120s is well
-        // above the time to extract one frame from any sane input.
-        let mut child = tokio::process::Command::new("ffmpeg")
-            .args([
-                "-i",
-                original.to_str().unwrap_or_default(),
-                "-vframes",
-                "1",
-                "-ss",
-                "00:00:01",
-                "-vf",
-                "scale=800:-1",
-                "-y",
-                thumb_path.to_str().unwrap_or_default(),
-            ])
-            .stdout(std::process::Stdio::piped())
-            .stderr(std::process::Stdio::piped())
-            .kill_on_drop(true)
-            .spawn()
-            .context("failed to spawn ffmpeg")?;
+        let produced =
+            crate::services::video::extract_poster_frame(original, &thumb_path, 800).await?;
 
-        let status = match tokio::time::timeout(
-            std::time::Duration::from_secs(120),
-            child.wait(),
-        )
-        .await
-        {
-            Ok(res) => res.context("ffmpeg wait failed")?,
-            Err(_) => {
-                let _ = child.kill().await;
-                anyhow::bail!("ffmpeg timeout after 120s");
-            }
-        };
-
-        if !status.success() {
-            // Best-effort: drain stderr for the log.
-            let mut stderr = Vec::new();
-            if let Some(mut handle) = child.stderr.take() {
-                use tokio::io::AsyncReadExt;
-                let _ = handle.read_to_end(&mut stderr).await;
-            }
-            anyhow::bail!(
-                "ffmpeg failed: {}",
-                String::from_utf8_lossy(&stderr)
-            );
-        }
-
-        Ok(format!("thumbnails/{thumb_filename}"))
+        Ok(produced.then(|| format!("thumbnails/{thumb_filename}")))
+    }
+}
+
+/// The blocking half of [`CompressionWorker::generate_image_derivatives`]: decode once, write
+/// both derivatives, then optionally shrink a PNG original in place.
+///
+/// A free function rather than an inline closure so its memory behaviour is directly testable —
+/// this is the code path that OOM-killed the container, and the fix is a scoping property that a
+/// future edit could silently undo.
+fn write_image_derivatives(
+    upload_id: Uuid,
+    original: &Path,
+    mime_type: &str,
+    preview_path: &Path,
+    display_path: &Path,
+) -> Result<()> {
+    let preview_max = CompressionWorker::PREVIEW_MAX_EDGE;
+    let display_max = CompressionWorker::DISPLAY_MAX_EDGE;
+
+    // THE FULL-SIZE DECODE IS SCOPED TO THIS BLOCK ON PURPOSE, and the block yields the
+    // DISPLAY derivative rather than the original.
+    //
+    // `img` is up to 256 MiB (imaging::decode_limits max_alloc) and `resize` only BORROWS it,
+    // so it used to stay alive through both resizes AND the oxipng call below — which decodes
+    // the PNG a second time and holds a full-size buffer per filter trial. That measured
+    // ~1250 MiB of peak RSS for a 2.8 MiB input, inside a 1 GiB cgroup: the container was
+    // SIGKILLed, taking every SSE stream and every in-flight upload with it.
+    //
+    // A block rather than a bare `drop(img)` because a `drop` call is one careless edit away
+    // from being removed as redundant-looking — and note the `else` arm MOVES `img` out, which
+    // is what makes "the block's value is the only survivor" true in both arms.
+    let (display, width, height) = {
+        // Decompression-bomb limits + EXIF orientation, both in one place — see
+        // services::imaging for why neither may be skipped.
+        let img = crate::services::imaging::decode_oriented(original)?;
+        let (width, height) = (img.width(), img.height());
+
+        // Display: max 2048px for the diashow. Only DOWNSCALE — never upscale a smaller
+        // original (that adds bytes with no quality gain); re-encode it as JPEG as-is.
+        let display = if width > display_max || height > display_max {
+            img.resize(
+                display_max,
+                display_max,
+                image::imageops::FilterType::Lanczos3,
+            )
+        } else {
+            img
+        };
+        (display, width, height)
+    };
+
+    display
+        .save_with_format(display_path, image::ImageFormat::Jpeg)
+        .context("failed to save display")?;
+
+    // Preview: max 800px, derived from the DISPLAY, not from the original.
+    //
+    // Both derivatives used to resize the full-size decode independently, so a 8000x8000
+    // original paid for two full-size Lanczos passes and their intermediates — measured 520
+    // MiB peak even after the scoping fix above, which two concurrent workers cannot fit in a
+    // 1 GiB container. Chaining 8000 -> 2048 -> 800 makes the second pass operate on 2048px
+    // input, and the full-size buffer is already freed by the time it runs. Quality is not the
+    // trade-off here: a staged Lanczos3 downscale to 800px is visually indistinguishable from
+    // a single-step one (and is a standard technique for large ratios).
+    display
+        .resize(
+            preview_max,
+            preview_max,
+            image::imageops::FilterType::Lanczos3,
+        )
+        .save_with_format(preview_path, image::ImageFormat::Jpeg)
+        .context("failed to save preview")?;
+    drop(display);
+
+    let pixels = u64::from(width) * u64::from(height);
+
+    // If the original is PNG, try lossless compression in place — but only when its pixel count
+    // is inside the budget, and never for longer than OXIPNG_TIMEOUT. This is a best-effort size
+    // saving: declining it costs disk, while attempting it unbounded cost the whole container.
+    if mime_type == "image/png" {
+        if pixels <= CompressionWorker::OXIPNG_MAX_PIXELS {
+            let mut opts = oxipng::Options::from_preset(2);
+            opts.timeout = Some(CompressionWorker::OXIPNG_TIMEOUT);
+            let _ = oxipng::optimize(
+                &oxipng::InFile::Path(original.to_path_buf()),
+                &oxipng::OutFile::Path {
+                    path: None,
+                    preserve_attrs: true,
+                },
+                &opts,
+            );
+        } else {
+            tracing::info!(
+                %upload_id, pixels,
+                "skipping oxipng: above the pixel budget; the original is stored as uploaded"
+            );
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Peak resident set of THIS process, in bytes, from `/proc/self/status`.
+    fn peak_rss_bytes() -> u64 {
+        let status = std::fs::read_to_string("/proc/self/status").expect("procfs");
+        let line = status
+            .lines()
+            .find(|l| l.starts_with("VmHWM:"))
+            .expect("VmHWM");
+        let kb: u64 = line
+            .split_whitespace()
+            .nth(1)
+            .and_then(|v| v.parse().ok())
+            .expect("VmHWM value");
+        kb * 1024
+    }
+
+    /// Reset the kernel's peak-RSS watermark so the measurement covers only what follows.
+    /// Linux 4.0+; writing "5" to `clear_refs` resets `VmHWM` to the current RSS.
+    fn reset_peak_rss() {
+        let _ = std::fs::write("/proc/self/clear_refs", "5");
+    }
+
+    /// The pixel gate has to sit below what the axis limits allow, or it can never fire.
+    #[test]
+    fn the_oxipng_gate_is_reachable_within_the_decode_limits() {
+        const _: () = {
+            // imaging::decode_limits permits 12_000 x 12_000 = 144 MP. A gate above that would
+            // never skip anything.
+            assert!(CompressionWorker::OXIPNG_MAX_PIXELS < 12_000 * 12_000);
+            // ...and it must stay above a 48 MP camera, so real photos still get optimised.
+            assert!(CompressionWorker::OXIPNG_MAX_PIXELS >= 8_000_000);
+        };
+    }
+
+    /// The heavy-image gate has to classify the two cases the way the sizing assumed:
+    /// an ordinary phone photo must NOT serialise, and the giant must.
+    #[test]
+    fn the_heavy_gate_separates_a_phone_photo_from_a_giant() {
+        let dir = std::env::temp_dir().join(format!("es-heavy-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+
+        // 12 MP, the shape of a default phone capture.
+        let ordinary = dir.join("ordinary.jpg");
+        image::RgbImage::new(4032, 3024).save(&ordinary).unwrap();
+        let ordinary_peak = crate::services::imaging::estimated_processing_peak_bytes(
+            &ordinary,
+            CompressionWorker::DISPLAY_MAX_EDGE,
+        )
+        .expect("header readable");
+        assert!(
+            ordinary_peak <= crate::services::imaging::HEAVY_IMAGE_BYTES,
+            "a 12 MP photo estimated at {} MiB would serialise the common path",
+            ordinary_peak / 1048576
+        );
+
+        // The 64 MP RGBA case that measured ~516 MiB peak.
+        let giant = dir.join("giant.png");
+        image::RgbaImage::new(8000, 8000).save(&giant).unwrap();
+        let giant_peak = crate::services::imaging::estimated_processing_peak_bytes(
+            &giant,
+            CompressionWorker::DISPLAY_MAX_EDGE,
+        )
+        .expect("header readable");
+        assert!(
+            giant_peak > crate::services::imaging::HEAVY_IMAGE_BYTES,
+            "an 8000x8000 RGBA original estimated at only {} MiB would be allowed to run \
+             concurrently with another one — 2x its real ~516 MiB peak does not fit in 1 GiB",
+            giant_peak / 1048576
+        );
+        // The estimate must also be in the right ballpark, not merely on the right side of the
+        // threshold: 244 MiB decode + 262 MiB f32 resize intermediate.
+        assert!(
+            (400..700).contains(&(giant_peak / 1048576)),
+            "estimate {} MiB is far from the measured ~516 MiB peak",
+            giant_peak / 1048576
+        );
+
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    /// The OOM that took the container down, measured rather than argued.
+    ///
+    /// An 8000x8000 RGBA PNG passes admission: 256,000,000 bytes is just under the 256 MiB
+    /// `max_alloc`, and smooth content is a few MB on disk, far under any size cap. The old
+    /// code kept that ~244 MiB decode alive across an unbounded, multi-threaded oxipng run and
+    /// peaked at ~1250 MiB — inside a 1 GiB cgroup. Being SIGKILLed there is not a blip: the
+    /// row was already committed, so the boot backfill replayed the identical workload on every
+    /// restart.
+    ///
+    /// `#[ignore]` because it allocates ~250 MiB and takes a few seconds. Run explicitly:
+    ///   cargo test --release oom -- --ignored --nocapture --test-threads=1
+    /// It must run ALONE — `VmHWM` is per process, so a concurrent test would pollute it.
+    #[test]
+    #[ignore = "heavy: allocates ~250 MiB; run with --ignored --test-threads=1"]
+    fn a_large_png_stays_far_below_the_container_limit() {
+        const EDGE: u32 = 8_000;
+        let dir = std::env::temp_dir().join(format!("es-oom-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        let original = dir.join("big.png");
+
+        // Smooth gradient: ~244 MiB decoded, a couple of MB on disk. That gap is the whole
+        // point — file size tells you nothing about what a PNG costs to process.
+        {
+            let mut buf = image::RgbaImage::new(EDGE, EDGE);
+            for (x, y, px) in buf.enumerate_pixels_mut() {
+                *px = image::Rgba([(x >> 5) as u8, (y >> 5) as u8, ((x + y) >> 6) as u8, 255]);
+            }
+            buf.save(&original).unwrap();
+        }
+
+        // Everything above is fixture setup, not the code under test.
+        reset_peak_rss();
+        let before = peak_rss_bytes();
+
+        write_image_derivatives(
+            Uuid::new_v4(),
+            &original,
+            "image/png",
+            &dir.join("preview.jpg"),
+            &dir.join("display.jpg"),
+        )
+        .expect("derivatives");
+
+        let peak = peak_rss_bytes();
+        let on_disk = std::fs::metadata(&original).unwrap().len();
+        eprintln!(
+            "input {:.2} MiB on disk ({EDGE}x{EDGE}); peak RSS {:.0} MiB (was {:.0} MiB before)",
+            on_disk as f64 / 1048576.0,
+            peak as f64 / 1048576.0,
+            before as f64 / 1048576.0
+        );
+
+        assert!(dir.join("preview.jpg").exists() && dir.join("display.jpg").exists());
+        // The container gets 1 GiB and runs two of these concurrently. 600 MiB is a generous
+        // ceiling that the old code (~1250 MiB) could not have met.
+        assert!(
+            peak < 600 * 1024 * 1024,
+            "peak RSS {} MiB — the decode is being held across oxipng again, or the pixel \
+             gate stopped firing",
+            peak / 1048576
+        );
+        let _ = std::fs::remove_dir_all(&dir);
     }
 }

backend/src/services/config.rs

@@ -1,46 +1,147 @@
-//! Reads of the runtime-tunable `config` table.
+//! Reads of the runtime-tunable `config` table, fronted by an in-memory cache.
 //!
 //! Each handler used to keep a small local copy of these helpers; consolidating them
 //! here means one place to add a parser, one place to mock for tests, and one place to
 //! find when a key changes. New keys do not require code changes — they're picked up
-//! the next time someone calls `get_*`.
+//! the next time the cache reloads.
+//!
+//! ## Why a cache
+//!
+//! The `config` table is effectively static during an event, yet it was the busiest
+//! query in the system: every request re-read each key with its own `SELECT`
+//! (an upload touched it ~8 times). Against the small connection pool that was the
+//! throughput ceiling. [`ConfigCache`] loads the whole table once and serves reads
+//! from memory.
+//!
+//! ## Consistency contract
+//!
+//! Correctness comes from **synchronous invalidation on every write**, not from the
+//! TTL. The two runtime write paths — the admin `PATCH /admin/config` handler and the
+//! test-mode truncate/reseed — both call [`ConfigCache::invalidate`] after committing,
+//! so the *next* read reloads from the DB and sees the new value immediately. The
+//! [`RELOAD_TTL`] is only a safety net for out-of-band changes (e.g. a migration or a
+//! manual DB edit); it is deliberately short but never the primary mechanism.
 //!
 //! Values are read with a default fallback so the app still starts if a key is missing
 //! (e.g. during a migration window). Production seeds keys via migrations 005 and 009.
 
+use std::collections::HashMap;
+use std::sync::{Arc, RwLock};
+use std::time::{Duration, Instant};
+
 use sqlx::PgPool;
 
-async fn fetch_raw(pool: &PgPool, key: &str) -> Option<String> {
-    sqlx::query_as::<_, (String,)>("SELECT value FROM config WHERE key = $1")
-        .bind(key)
-        .fetch_optional(pool)
+/// How long a loaded snapshot is trusted before the next read reloads it. This is a
+/// backstop for out-of-band DB changes only — every in-process write invalidates the
+/// cache synchronously, so tests that PATCH-then-assert never depend on this expiring.
+const RELOAD_TTL: Duration = Duration::from_secs(30);
+
+struct Snapshot {
+    values: HashMap<String, String>,
+    loaded_at: Instant,
+}
+
+/// In-memory cache of the entire `config` table. Cheap to `clone` (shares the pool and
+/// the `Arc`), so it lives in `AppState` and every handler reads through it.
+#[derive(Clone)]
+pub struct ConfigCache {
+    pool: PgPool,
+    inner: Arc<RwLock<Option<Snapshot>>>,
+}
+
+impl ConfigCache {
+    pub fn new(pool: PgPool) -> Self {
+        Self {
+            pool,
+            inner: Arc::new(RwLock::new(None)),
+        }
+    }
+
+    /// Drop the cached snapshot so the next read reloads the whole table from the DB.
+    /// Call this after any write to the `config` table (admin PATCH, test reseed).
+    pub fn invalidate(&self) {
+        *self.inner.write().unwrap() = None;
+    }
+
+    /// Return the fresh snapshot if one is loaded and still within [`RELOAD_TTL`].
+    fn fresh_snapshot(&self) -> Option<HashMap<String, String>> {
+        let guard = self.inner.read().unwrap();
+        match guard.as_ref() {
+            Some(snap) if snap.loaded_at.elapsed() < RELOAD_TTL => Some(snap.values.clone()),
+            _ => None,
+        }
+    }
+
+    /// Read one key, loading the whole table into the cache on a miss/expiry. On a DB
+    /// error we return `None` (callers fall back to their default) without poisoning
+    /// the cache.
+    async fn get_raw(&self, key: &str) -> Option<String> {
+        if let Some(values) = self.fresh_snapshot() {
+            return values.get(key).cloned();
+        }
+
+        // Cache miss or stale — reload the entire table in one query.
+        let rows: Vec<(String, String)> = match sqlx::query_as::<_, (String, String)>(
+            "SELECT key, value FROM config",
+        )
+        .fetch_all(&self.pool)
         .await
-        .ok()
-        .flatten()
-        .map(|(v,)| v)
+        {
+            Ok(rows) => rows,
+            Err(e) => {
+                tracing::warn!(error = ?e, "config reload failed; using defaults for this read");
+                return None;
+            }
+        };
+
+        let values: HashMap<String, String> = rows.into_iter().collect();
+        let result = values.get(key).cloned();
+        *self.inner.write().unwrap() = Some(Snapshot {
+            values,
+            loaded_at: Instant::now(),
+        });
+        result
+    }
 }
 
-pub async fn get_str(pool: &PgPool, key: &str, default: &str) -> String {
-    fetch_raw(pool, key).await.unwrap_or_else(|| default.to_string())
+pub async fn get_str(cache: &ConfigCache, key: &str, default: &str) -> String {
+    cache
+        .get_raw(key)
+        .await
+        .unwrap_or_else(|| default.to_string())
 }
 
-pub async fn get_i64(pool: &PgPool, key: &str, default: i64) -> i64 {
-    fetch_raw(pool, key).await.and_then(|v| v.parse().ok()).unwrap_or(default)
+pub async fn get_i64(cache: &ConfigCache, key: &str, default: i64) -> i64 {
+    cache
+        .get_raw(key)
+        .await
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(default)
 }
 
-pub async fn get_usize(pool: &PgPool, key: &str, default: usize) -> usize {
-    fetch_raw(pool, key).await.and_then(|v| v.parse().ok()).unwrap_or(default)
+pub async fn get_usize(cache: &ConfigCache, key: &str, default: usize) -> usize {
+    cache
+        .get_raw(key)
+        .await
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(default)
 }
 
-pub async fn get_f64(pool: &PgPool, key: &str, default: f64) -> f64 {
-    fetch_raw(pool, key).await.and_then(|v| v.parse().ok()).unwrap_or(default)
+pub async fn get_f64(cache: &ConfigCache, key: &str, default: f64) -> f64 {
+    cache
+        .get_raw(key)
+        .await
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(default)
 }
 
 /// Parses common truthy spellings used by both the migration seeds and the admin form.
 /// Accepts `true/false`, `1/0`, `yes/no`, `on/off` — case-insensitive. Anything else
 /// returns `default`.
-pub async fn get_bool(pool: &PgPool, key: &str, default: bool) -> bool {
-    let Some(raw) = fetch_raw(pool, key).await else { return default };
+pub async fn get_bool(cache: &ConfigCache, key: &str, default: bool) -> bool {
+    let Some(raw) = cache.get_raw(key).await else {
+        return default;
+    };
     match raw.trim().to_ascii_lowercase().as_str() {
         "true" | "1" | "yes" | "on" => true,
         "false" | "0" | "no" | "off" => false,

backend/src/services/disk.rs

@@ -0,0 +1,169 @@
+//! Cached view of the filesystem backing the media directory.
+//!
+//! Free/total disk space is needed on two hot paths — the per-user storage quota
+//! (checked on every upload *and* every `GET /me/quota` poll) and the admin stats
+//! endpoint. Reading it means `sysinfo::Disks::new_with_refreshed_list()`, which stats
+//! every mounted filesystem; doing that per request is wasteful for a number that
+//! barely moves. [`DiskCache`] refreshes it at most once per [`TTL`] and serves the
+//! rest from memory.
+
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, RwLock};
+use std::time::{Duration, Instant};
+
+/// How long a disk reading is trusted before the next call re-stats the filesystem.
+const TTL: Duration = Duration::from_secs(15);
+
+#[derive(Clone, Copy)]
+pub struct DiskInfo {
+    pub total: u64,
+    pub free: u64,
+}
+
+/// Cheap-to-clone cache of the media filesystem's total/free bytes. Lives in
+/// `AppState`.
+#[derive(Clone)]
+pub struct DiskCache {
+    inner: Arc<RwLock<Option<(PathBuf, DiskInfo, Instant)>>>,
+}
+
+impl DiskCache {
+    pub fn new() -> Self {
+        Self {
+            inner: Arc::new(RwLock::new(None)),
+        }
+    }
+
+    /// Drop the cached reading so the next `snapshot()` re-measures the filesystem.
+    ///
+    /// Used by the e2e TRUNCATE endpoint. Truncating deletes every uploaded file, which materially
+    /// changes free space — but the cached reading survives for up to the TTL, so the next test can
+    /// compute a quota from the PREVIOUS test's disk. That matters now that the quota tests steer
+    /// the per-user limit off `free_disk_bytes`: a stale reading makes the limit wrong and the test
+    /// flaky, for reasons that have nothing to do with the code under test.
+    pub fn invalidate(&self) {
+        *self.inner.write().unwrap() = None;
+    }
+
+    /// Cached `(total, free)` bytes for the filesystem that holds `media_path`.
+    ///
+    /// Returns `None` when the mount can't be resolved — callers MUST treat that as
+    /// "unknown", never "zero free". (The quota path in particular fails *open* on
+    /// `None`: enforcing a 0-byte limit would lock every user out of uploading.)
+    /// Cached free-space reading for `path`.
+    ///
+    /// The cache is keyed BY PATH. It used to hold a single slot and ignore its argument on a hit,
+    /// so it would happily return the media volume's numbers for any other path within the TTL.
+    /// That was invisible only because every caller happened to pass `media_path` — the first
+    /// caller to ask about a different volume (e.g. the exports volume, which is a separate mount)
+    /// would have silently got the wrong filesystem's free space.
+    pub fn snapshot(&self, path: &Path) -> Option<DiskInfo> {
+        if let Some((cached_path, info, at)) = self.inner.read().unwrap().as_ref()
+            && cached_path == path
+            && at.elapsed() < TTL
+        {
+            return Some(*info);
+        }
+        let info = read_disk_for_path(path)?;
+        *self.inner.write().unwrap() = Some((path.to_path_buf(), info, Instant::now()));
+        Some(info)
+    }
+}
+
+impl Default for DiskCache {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// UNCACHED free-space reading for the filesystem backing `path`.
+///
+/// Deliberately bypasses [`DiskCache`]. The cache exists for the quota poll, where a 15s-stale
+/// number is fine because it is only ever advisory. The export preflight is the opposite case: it
+/// decides whether to start writing a multi-GB archive, and the sibling export worker running
+/// concurrently can move free space by tens of gigabytes well inside the TTL. A stale reading there
+/// would authorise exactly the write that fills the disk.
+pub fn free_bytes(path: &Path) -> Option<u64> {
+    read_disk_for_path(path).map(|d| d.free)
+}
+
+/// Resolve the filesystem backing `media_path` and read its total/free bytes.
+///
+/// Snapshots the mount table via `sysinfo`, then delegates the selection to the pure
+/// [`select_disk`] so the (fiddly, edge-case-prone) matching logic is unit-testable
+/// without touching the real filesystem.
+fn read_disk_for_path(media_path: &Path) -> Option<DiskInfo> {
+    let disks = sysinfo::Disks::new_with_refreshed_list();
+    let mounts: Vec<(String, u64, u64)> = disks
+        .iter()
+        .map(|d| {
+            (
+                d.mount_point().to_string_lossy().to_string(),
+                d.total_space(),
+                d.available_space(),
+            )
+        })
+        .collect();
+    select_disk(&mounts, &media_path.to_string_lossy())
+}
+
+/// Pick the filesystem for `media_path` from a `(mount_point, total, free)` table.
+///
+/// Chooses the **longest** mount point that is a prefix of `media_path` (the most
+/// specific filesystem) rather than the first match — otherwise the root `/` mount,
+/// which prefixes every absolute path, could shadow a dedicated `/media` volume. Falls
+/// back to `/` when nothing prefixes the path (e.g. a relative media path), and to
+/// `None` when even that is absent — the caller treats `None` as "unknown" and fails
+/// open on quota.
+fn select_disk(mounts: &[(String, u64, u64)], media_path: &str) -> Option<DiskInfo> {
+    mounts
+        .iter()
+        .filter(|(mp, _, _)| media_path.starts_with(mp.as_str()))
+        .max_by_key(|(mp, _, _)| mp.len())
+        .or_else(|| mounts.iter().find(|(mp, _, _)| mp == "/"))
+        .map(|(_, total, free)| DiskInfo {
+            total: *total,
+            free: *free,
+        })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::select_disk;
+
+    #[test]
+    fn picks_longest_matching_mount() {
+        // Both "/" and "/media" prefix the path; the dedicated volume must win.
+        let mounts = vec![("/".to_string(), 100, 40), ("/media".to_string(), 200, 150)];
+        let d = select_disk(&mounts, "/media/originals/x.jpg").unwrap();
+        assert_eq!((d.total, d.free), (200, 150));
+    }
+
+    #[test]
+    fn falls_back_to_root_when_no_specific_mount_matches() {
+        let mounts = vec![("/".to_string(), 100, 40), ("/media".to_string(), 200, 150)];
+        // "/var/lib" is only prefixed by "/".
+        let d = select_disk(&mounts, "/var/lib/data").unwrap();
+        assert_eq!((d.total, d.free), (100, 40));
+    }
+
+    #[test]
+    fn relative_path_uses_root_fallback() {
+        let mounts = vec![("/".to_string(), 100, 40)];
+        // A relative path prefixes nothing, so the explicit "/" fallback applies.
+        let d = select_disk(&mounts, "media/originals").unwrap();
+        assert_eq!((d.total, d.free), (100, 40));
+    }
+
+    #[test]
+    fn none_when_no_mount_matches_and_no_root() {
+        // No "/" present and nothing prefixes the relative path → unknown (fail-open).
+        let mounts = vec![("/data".to_string(), 100, 40)];
+        assert!(select_disk(&mounts, "relative/path").is_none());
+    }
+
+    #[test]
+    fn none_on_empty_mount_table() {
+        assert!(select_disk(&[], "/media/x").is_none());
+    }
+}

backend/src/services/imaging.rs

@@ -0,0 +1,388 @@
+//! Shared image decoding.
+//!
+//! Exists so there is exactly ONE way to turn a file on disk into a `DynamicImage` in this
+//! codebase. Two properties have to hold everywhere an image is decoded, and both were
+//! previously re-derived per call site — which is how they drifted apart:
+//!
+//! - **EXIF orientation must be applied.** Phones do not rotate sensor data; they record how
+//!   the camera was held in a tag and store the pixels as shot. `image::open` and
+//!   `ImageReader::decode` both hand back the raw pixels and ignore that tag, and re-encoding
+//!   to JPEG writes no EXIF, so the derivative is permanently sideways while the untouched
+//!   original still renders upright. The compression worker was fixed; the export worker was
+//!   not, so every portrait photo came out sideways in the keepsake's HTML viewer.
+//! - **Decode limits must be set.** The upload body cap bounds the file on disk, but a small
+//!   file can decode to enormous dimensions (a ~1 MB image expanding to 50k×50k px), OOM-ing
+//!   the box. `image::open` applies NO limits at all, so the export path was also decoding
+//!   arbitrary user-supplied images unbounded.
+
+use anyhow::{Context, Result};
+use image::{DynamicImage, ImageDecoder};
+use std::path::Path;
+
+/// Bounds for any decode of user-supplied image data. The per-axis cap covers any real phone
+/// photo; `max_alloc` bounds the decoded buffer — but only because `decode_oriented` reserves
+/// against it explicitly, see there.
+///
+/// Sized against the deployment: the app container is capped at 1 GiB and the compression
+/// worker runs `compression_concurrency` decodes at once (default 2), so 256 MiB per decode
+/// leaves headroom for the resize buffers and the runtime.
+fn decode_limits() -> image::Limits {
+    let mut limits = image::Limits::default();
+    limits.max_image_width = Some(12_000);
+    limits.max_image_height = Some(12_000);
+    limits.max_alloc = Some(256 * 1024 * 1024);
+    limits
+}
+
+/// True when re-running the exact same work on the exact same bytes cannot possibly
+/// succeed, so retrying only burns wall-clock and log noise.
+///
+/// Deliberately narrow. Only the `ImageError` variants that are a property of the *input*
+/// count: the file will not shrink, gain codec support, or un-corrupt itself between
+/// attempts. `IoError` is excluded on purpose — EMFILE under load, or a momentarily
+/// unreadable file, is exactly the transient case the retry exists for. A FULL disk is the
+/// one io error that must not be retried either, but for a different reason and with a
+/// different remedy; see [`is_storage_full_error`].
+pub fn is_permanent_image_error(err: &anyhow::Error) -> bool {
+    err.chain().any(|cause| {
+        matches!(
+            cause.downcast_ref::<image::ImageError>(),
+            Some(
+                image::ImageError::Limits(_)
+                    | image::ImageError::Unsupported(_)
+                    | image::ImageError::Decoding(_)
+            )
+        )
+    })
+}
+
+/// True when the failure is the media filesystem being out of space.
+///
+/// Deliberately separate from [`is_permanent_image_error`], which is about the *input*. ENOSPC
+/// is about the *host*, and it is the one failure the retry loop actively makes worse: a disk
+/// does not drain during six seconds of backoff, so all three attempts fail identically while
+/// holding a compression permit that photos are queued behind.
+///
+/// The give-up path it fed was worse still. It refunded the guest's quota and soft-deleted the
+/// row while deliberately RETAINING the original — so the bytes stayed on the full disk, the
+/// photo vanished from the feed seconds after a `201 Created`, and the guest was handed back
+/// the quota to upload it again into the same full disk. Each round shrank free space further.
+pub fn is_storage_full_error(err: &anyhow::Error) -> bool {
+    fn is_full(io: &std::io::Error) -> bool {
+        // `StorageFull` is the portable classification; the raw ENOSPC catches the paths where
+        // the OS error was never mapped to a named kind.
+        io.kind() == std::io::ErrorKind::StorageFull || io.raw_os_error() == Some(28)
+    }
+    err.chain().any(|cause| {
+        // `image` wraps the io error in its own variant rather than exposing it as a source,
+        // so the plain downcast alone would miss every derivative-write failure.
+        cause.downcast_ref::<std::io::Error>().is_some_and(is_full)
+            || matches!(
+                cause.downcast_ref::<image::ImageError>(),
+                Some(image::ImageError::IoError(io)) if is_full(io)
+            )
+    })
+}
+
+/// Build a decoder for `path` with the budget enforced, WITHOUT reading any pixels.
+///
+/// Single source of truth for "may this image be decoded at all": both the upload
+/// admission check and the compression worker go through here, so they cannot disagree
+/// about what is acceptable.
+fn decoder_within_budget(path: &Path) -> Result<impl image::ImageDecoder> {
+    let mut reader = image::ImageReader::open(path)
+        .context("failed to open image")?
+        .with_guessed_format()
+        .context("failed to read image header")?;
+    let mut limits = decode_limits();
+    reader.limits(limits.clone());
+
+    // We need `into_decoder` rather than `decode()` to read the EXIF orientation tag before
+    // the pixels are consumed. But the two are NOT equivalent on safety: `decode()` performs
+    //
+    //     limits.reserve(decoder.total_bytes())?;
+    //
+    // between building the decoder and reading the image, and `into_decoder()` skips it (the
+    // crate's own FIXME concedes `from_decoder` doesn't compensate). Nothing else enforces
+    // `max_alloc` — the JPEG decoder's `set_limits` only checks support and dimensions — so
+    // without the line below the budget is inert and the ONLY bound is the per-axis cap. That
+    // leaves 12000x12000 decodable at 412 MiB, and two concurrent at 824 MiB against a 1 GiB
+    // container. Re-add it, exactly as `decode()` does.
+    let mut decoder = reader.into_decoder().context("failed to decode image")?;
+    limits
+        .reserve(decoder.total_bytes())
+        .context("image too large to decode within the memory budget")?;
+    decoder
+        .set_limits(limits)
+        .context("image too large to decode within the memory budget")?;
+    Ok(decoder)
+}
+
+/// Rough peak heap an image will cost to turn into derivatives, read from the HEADER only —
+/// no pixels are decoded. `None` when the header can't be read or the image is over budget
+/// (the caller is about to fail on it anyway).
+///
+/// Two terms, and the second is the one that surprises:
+///
+/// - the decoded buffer, `width * height * channels`; and
+/// - the resize intermediate. `image`'s Lanczos3 path accumulates in `f32`, so the buffer
+///   between the horizontal and vertical passes is `new_width * old_height * 4 channels * 4
+///   bytes` — 16 bytes per pixel-row-slot, not the 4 the output uses. For an 8000x8000
+///   original that is 262 MiB on top of a 244 MiB decode, measured. It is bigger than the
+///   decode for any tall image, which is why "the decode is bounded by max_alloc" was never
+///   the whole story.
+///
+/// Used to decide whether an image is heavy enough to need exclusive use of the box's memory
+/// headroom, NOT to reject anything.
+pub fn estimated_processing_peak_bytes(path: &Path, display_edge: u32) -> Option<u64> {
+    let decoder = decoder_within_budget(path).ok()?;
+    let (width, height) = decoder.dimensions();
+    let decoded = decoder.total_bytes();
+
+    // Aspect-preserving fit into `display_edge`, matching DynamicImage::resize. No downscale
+    // means no intermediate at all.
+    let intermediate = if width > display_edge || height > display_edge {
+        let ratio = f64::from(display_edge) / f64::from(width.max(height));
+        let new_width = (f64::from(width) * ratio).round().max(1.0) as u64;
+        new_width * u64::from(height) * 16
+    } else {
+        0
+    };
+
+    Some(decoded.saturating_add(intermediate))
+}
+
+/// Megapixels an image would decode to, or `None` if its header can't be read. Used only
+/// to put a concrete number in the message the guest sees.
+pub fn megapixels(path: &Path) -> Option<f64> {
+    let reader = image::ImageReader::open(path)
+        .ok()?
+        .with_guessed_format()
+        .ok()?;
+    let (w, h) = reader.into_dimensions().ok()?;
+    Some(f64::from(w) * f64::from(h) / 1_000_000.0)
+}
+
+/// True when an image cannot be decoded specifically because it would exceed the memory
+/// budget — read from the header, no pixels touched.
+///
+/// Called at upload admission so a guest who sends a 100 MP photo is told at the door, with
+/// a reason they can act on, instead of the upload being accepted with a 201 and then
+/// silently soft-deleted minutes later when the worker gives up on it.
+///
+/// Deliberately narrow: ONLY the budget. A corrupt, truncated or unsupported file also
+/// fails to build a decoder, but rejecting those here would change a contract the
+/// adversarial suite pins on purpose — acceptance follows the magic bytes, and a payload
+/// with a valid JPEG header is accepted regardless of what follows it. Those go to the
+/// compression worker as before, which handles them gracefully and (since the retry
+/// classifier) no longer burns backoff on them.
+pub fn exceeds_decode_budget(path: &Path) -> bool {
+    match decoder_within_budget(path) {
+        Ok(_) => false,
+        Err(e) => e.chain().any(|cause| {
+            matches!(
+                cause.downcast_ref::<image::ImageError>(),
+                Some(image::ImageError::Limits(_))
+            )
+        }),
+    }
+}
+
+/// Decode an image from disk with decompression-bomb limits applied and its EXIF
+/// orientation baked into the pixels.
+///
+/// Blocking — call inside `spawn_blocking`.
+pub fn decode_oriented(path: &Path) -> Result<DynamicImage> {
+    let mut decoder = decoder_within_budget(path)?;
+
+    // Cheap, and it happens BEFORE any pixels are read: an oversized image costs a header
+    // parse, not an allocation.
+    let orientation = decoder
+        .orientation()
+        .unwrap_or(image::metadata::Orientation::NoTransforms);
+    let mut img = DynamicImage::from_decoder(decoder).context("failed to decode image")?;
+    img.apply_orientation(orientation);
+    Ok(img)
+}
+
+/// Process-wide serialisation for memory-heavy image work.
+///
+/// The `app` container gets 1 GiB. A single 8000x8000 original measures ~516 MiB peak even with
+/// the decode correctly scoped, so two overlapping giants is an OOM kill — and the kernel kills
+/// the whole process, dropping every SSE stream and stranding every in-flight upload.
+///
+/// GLOBAL rather than a field on `CompressionWorker`, because the constraint is the container's
+/// memory and there is more than one producer of this work. The export's own image path
+/// (`services::export`) decodes and resizes every photo in the gallery — a thumbnail for each,
+/// plus a 2000px re-encode for every original over 5 MB — and it ran in a bare `spawn_blocking`
+/// with no permit at all. So "host taps Freigeben while the last phone photos are still
+/// compressing" put an export decode and a heavy compression job in the same cgroup at the same
+/// time, which is the scenario the permit exists to make impossible. Worse, it is self-repeating:
+/// the OOM kill marks the export failed, and `recover_exports` re-spawns it on boot into the same
+/// conditions.
+///
+/// Held across the blocking section and released on drop, including on error.
+pub static HEAVY_IMAGE_PERMITS: std::sync::LazyLock<tokio::sync::Semaphore> =
+    std::sync::LazyLock::new(|| tokio::sync::Semaphore::new(1));
+
+/// Estimated peak heap above which a job must take [`HEAVY_IMAGE_PERMITS`].
+///
+/// 150 MiB sits far above a normal phone photo (a 12 MP JPEG costs ~50 MiB all-in) so the common
+/// path never serialises, and far below the point where two jobs stop fitting in the container.
+pub const HEAVY_IMAGE_BYTES: u64 = 150 * 1024 * 1024;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Shared with the e2e suite rather than duplicating 568 KiB of binary: the same file
+    /// drives `02-upload/oversized-image` so both layers assert on one artefact.
+    const HUGE: &str = concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/../e2e/fixtures/media/huge-99mp.jpg"
+    );
+
+    #[test]
+    fn rejects_an_image_that_would_blow_the_allocation_budget() {
+        // 11000x9000 = 99 MP. Deliberately UNDER the 12000px per-axis cap, so the axis check
+        // cannot reject it — the allocation budget is the only thing that can, which is
+        // exactly what makes this a regression test rather than a restatement of the axis cap.
+        // 283 MiB decoded as RGB8 against a 256 MiB budget, from 568 KiB on disk.
+        //
+        // This failed before the guard was restored: `ImageReader::decode` performs
+        // `limits.reserve(decoder.total_bytes())`, and `into_decoder()` — which we need for
+        // the EXIF tag — skips it, so `max_alloc` was inert and this decoded happily.
+        // Map the Ok arm to its dimensions first: on failure `expect_err` Debug-prints the
+        // value, and Debug on a DynamicImage dumps every pixel — 283 MiB of output.
+        let err = decode_oriented(Path::new(HUGE))
+            .map(|img| (img.width(), img.height()))
+            .expect_err("a 99 MP image must be refused, not allocated");
+        let msg = format!("{err:#}");
+        assert!(
+            msg.to_lowercase().contains("limit") || msg.to_lowercase().contains("memory"),
+            "expected a limits error, got: {msg}"
+        );
+    }
+
+    #[test]
+    fn an_oversized_image_is_a_permanent_failure() {
+        // The retry loop must not burn 2s + 4s of backoff on this: the file will not shrink
+        // between attempts, so all three attempts reach the identical conclusion.
+        let err = decode_oriented(Path::new(HUGE))
+            .map(|img| (img.width(), img.height()))
+            .expect_err("fixture must exceed the budget");
+        assert!(
+            is_permanent_image_error(&err),
+            "a Limits error can never succeed on retry: {err:#}"
+        );
+    }
+
+    #[test]
+    fn a_plain_io_error_is_not_permanent() {
+        // The mirror that keeps the classifier honest. EMFILE under load, or a momentary
+        // unreadable file, is exactly what the retry exists for — misclassifying those as
+        // permanent would turn a transient blip back into the data loss round 1 fixed.
+        // (A FULL disk is its own case now; see the storage-full tests below.)
+        let err = decode_oriented(Path::new("/nonexistent/definitely-not-here.jpg"))
+            .map(|img| (img.width(), img.height()))
+            .expect_err("a missing file must error");
+        assert!(
+            !is_permanent_image_error(&err),
+            "an IO error must stay retryable: {err:#}"
+        );
+    }
+
+    #[test]
+    fn a_full_disk_is_recognised_through_both_wrappers() {
+        // The two shapes ENOSPC actually arrives in. A bare io::Error is what `tokio::fs` and
+        // `std::fs` produce; the `image` crate wraps its own in `ImageError::IoError`, which is
+        // NOT reachable via `source()` — so a chain walk that only downcast to io::Error would
+        // miss every derivative-write failure, i.e. the exact case this classifier exists for.
+        let bare = anyhow::Error::from(std::io::Error::from(std::io::ErrorKind::StorageFull))
+            .context("failed to write the preview");
+        assert!(is_storage_full_error(&bare), "bare io::Error: {bare:#}");
+
+        let wrapped = anyhow::Error::from(image::ImageError::IoError(std::io::Error::from(
+            std::io::ErrorKind::StorageFull,
+        )))
+        .context("failed to save the display derivative");
+        assert!(
+            is_storage_full_error(&wrapped),
+            "ImageError::IoError: {wrapped:#}"
+        );
+    }
+
+    #[test]
+    fn an_ordinary_io_error_is_not_a_full_disk() {
+        // Keeps the classifier from swallowing the general case: only ENOSPC may skip the retry
+        // and take the keep-the-row branch. Anything else must still be retried and, if it keeps
+        // failing, soft-deleted as before.
+        let missing = decode_oriented(Path::new("/nonexistent/definitely-not-here.jpg"))
+            .map(|img| (img.width(), img.height()))
+            .expect_err("a missing file must error");
+        assert!(
+            !is_storage_full_error(&missing),
+            "a missing file is not a full disk: {missing:#}"
+        );
+    }
+
+    #[test]
+    fn admission_rejects_only_the_over_budget_case() {
+        // Admission and processing must agree about SIZE — a photo accepted at the door and
+        // then rejected by the worker for being too big is the failure this pair prevents.
+        assert!(
+            exceeds_decode_budget(Path::new(HUGE)),
+            "admission must reject what the decoder rejects for size"
+        );
+        let ordinary = concat!(
+            env!("CARGO_MANIFEST_DIR"),
+            "/../e2e/fixtures/media/portrait-exif6.jpg"
+        );
+        assert!(
+            !exceeds_decode_budget(Path::new(ordinary)),
+            "admission must accept an ordinary photo"
+        );
+    }
+
+    #[test]
+    fn admission_does_not_reject_a_merely_undecodable_file() {
+        // The narrowing that keeps the adversarial contract intact: a payload with valid
+        // JPEG magic bytes and nothing behind them cannot be decoded, but acceptance follows
+        // the magic bytes by design (07-adversarial/file-upload-attacks). It is the worker's
+        // job to fail it, not admission's — admission is only the resource guard.
+        let dir = std::env::temp_dir().join("eventsnap-imaging-test");
+        std::fs::create_dir_all(&dir).expect("tmp dir");
+        let stub = dir.join("magic-only.jpg");
+        let mut bytes = vec![0u8; 1024];
+        bytes[..3].copy_from_slice(&[0xFF, 0xD8, 0xFF]);
+        std::fs::write(&stub, &bytes).expect("write stub");
+
+        assert!(
+            !exceeds_decode_budget(&stub),
+            "a corrupt file is not an over-budget file"
+        );
+        assert!(
+            decode_oriented(&stub)
+                .map(|i| (i.width(), i.height()))
+                .is_err(),
+            "...but it must still fail in the worker"
+        );
+        let _ = std::fs::remove_file(&stub);
+    }
+
+    #[test]
+    fn still_decodes_an_ordinary_photo_and_applies_orientation() {
+        // The guard must not have become a blanket refusal. This fixture is 40x20 stored with
+        // EXIF Orientation=6, so a correct decode returns it rotated to 20x40 portrait.
+        let path = concat!(
+            env!("CARGO_MANIFEST_DIR"),
+            "/../e2e/fixtures/media/portrait-exif6.jpg"
+        );
+        let img = decode_oriented(Path::new(path)).expect("an ordinary photo must decode");
+        assert_eq!(
+            (img.width(), img.height()),
+            (20, 40),
+            "EXIF orientation must still be applied after restoring the guard"
+        );
+    }
+}

backend/src/services/jobs.rs

@@ -1,73 +0,0 @@
-//! Shared shape for long-running background work.
-//!
-//! Today's [`compression`](crate::services::compression) and [`export`](crate::services::export)
-//! pipelines each implement their own progress + SSE plumbing. They could converge on the
-//! trait sketched here so future jobs (analytics, archival, ...) plug into one progress
-//! pipeline.
-//!
-//! This module is intentionally a *sketch*: the existing services are not yet wired to
-//! it. The aim is to (a) document the convention so new jobs follow it, (b) make the
-//! refactor mechanical when someone is ready to do it. See `docs/IDEAS.md` —
-//! "Maintainability principles" — for the rationale.
-//!
-//! Example of an eventual implementor:
-//!
-//! ```ignore
-//! struct ZipExport { event_id: Uuid, /* … */ }
-//!
-//! impl BackgroundJob for ZipExport {
-//!     fn name(&self) -> &'static str { "zip-export" }
-//!     async fn run(self, ctx: JobContext) -> Result<()> {
-//!         for (i, item) in items.iter().enumerate() {
-//!             ctx.report(percent(i, items.len())).await?;
-//!             // … write to zip …
-//!         }
-//!         Ok(())
-//!     }
-//! }
-//! ```
-
-use anyhow::Result;
-
-/// Handle handed to a running job: reports progress and emits SSE events.
-///
-/// Wraps the existing SSE broadcaster and an optional `export_job` row. Implementors
-/// don't need to know about `state.sse_tx` directly — they call [`JobContext::report`]
-/// and get the same effect.
-pub struct JobContext {
-    pub job_id: Option<uuid::Uuid>,
-    pub event_kind: &'static str,
-    pub sse_tx: tokio::sync::broadcast::Sender<crate::state::SseEvent>,
-    pub pool: sqlx::PgPool,
-}
-
-impl JobContext {
-    /// Update progress (0..=100) and broadcast an SSE tick. Cheap to call often —
-    /// rate-limit at the call site if a job emits at > 10 Hz.
-    pub async fn report(&self, percent: u8) -> Result<()> {
-        if let Some(job_id) = self.job_id {
-            sqlx::query("UPDATE export_job SET progress_pct = $1 WHERE id = $2")
-                .bind(percent as i16)
-                .bind(job_id)
-                .execute(&self.pool)
-                .await?;
-        }
-        let _ = self.sse_tx.send(crate::state::SseEvent::new(
-            self.event_kind,
-            serde_json::json!({ "progress_pct": percent }).to_string(),
-        ));
-        Ok(())
-    }
-}
-
-/// One unit of work that publishes progress through a [`JobContext`].
-///
-/// `run` consumes `self`; spawn with `tokio::spawn` at the caller. Errors propagate;
-/// the caller is responsible for mapping them to `export_job.error_message` or
-/// equivalent. Implementors stay small — the trait deliberately has no `cancel`
-/// or `pause`; we have not needed those yet.
-#[allow(async_fn_in_trait)]
-pub trait BackgroundJob: Send + 'static {
-    fn name(&self) -> &'static str;
-    async fn run(self, ctx: JobContext) -> Result<()>;
-}

backend/src/services/maintenance.rs

@@ -9,9 +9,11 @@
 //!    users staring at a spinner. Resetting them on startup recovers gracefully.
 //!
 //! 2. **Periodic tasks** — pruning that should happen "every hour" rather than per
-//!    request: expired sessions (otherwise the table grows unboundedly), and the
+//!    request: expired sessions (otherwise the table grows unboundedly), the
 //!    rate-limiter's in-memory windows (so keys for IPs that left long ago don't
-//!    accumulate).
+//!    accumulate), and the media of soft-deleted uploads — both the ones whose compression
+//!    permanently failed and the ones a guest or host deliberately removed — which are
+//!    retained for a recovery window and then reclaimed.
 
 use std::path::PathBuf;
 use std::time::Duration;
@@ -21,6 +23,42 @@ use sqlx::PgPool;
 use crate::services::rate_limiter::RateLimiter;
 use crate::services::sse_tickets::SseTicketStore;
 
+/// How long a permanently-failed upload's original is kept on disk before it is
+/// reclaimed.
+///
+/// The compression worker stops deleting originals on failure — a transient error must
+/// never destroy the guest's only copy of a photo they can't retake. But the row is
+/// soft-deleted and the uploader's quota IS refunded, so without a sweep those bytes are
+/// invisible, unowned, and free: a reproducible codec failure lets one guest accumulate
+/// orphans at no personal cost, and because `active_uploaders` counts only users with
+/// non-deleted uploads, dropping out of that count actually RAISES everyone's per-user
+/// ceiling while the disk gets fuller.
+///
+/// Two weeks is comfortably longer than any single event, so an operator investigating a
+/// failed upload still has the file, while the leak stays bounded.
+const FAILED_ORIGINAL_RETENTION_DAYS: i64 = 14;
+
+/// How long a DELIBERATELY deleted upload's files are kept before they are reclaimed.
+///
+/// The same leak, reached by the ordinary path rather than the exceptional one.
+/// `soft_delete_in_event` stamps `deleted_at` and refunds `total_upload_bytes`, but nothing ever
+/// removed the bytes — so the quota stopped bounding the disk. Upload 500 MB, delete, quota is back
+/// to zero, upload another 500 MB: not an attack, just a guest curating their camera roll, which is
+/// what people do. The host then sees guests hitting "Du hast dein Upload-Limit erreicht" while the
+/// admin widget shows a disk full of files no upload row points at, and the quota message is
+/// actively misleading because the space really is gone — just not to anyone the accounting can
+/// name.
+///
+/// Much shorter than the failure window on purpose. Fourteen days outlives the whole event, so a
+/// deliberate delete would never reclaim anything while it mattered. A day still gives an operator
+/// a recovery window for a mis-tap.
+///
+/// NOTE what this does NOT do: within the window the bytes are still spent and still unaccounted,
+/// so a guest deleting and re-uploading through an eight-hour event can outrun the sweep. Bounding
+/// that would mean holding the quota until the file is actually reclaimed rather than refunding at
+/// `deleted_at` — a deliberate trade, and the reason the low-disk warning exists.
+const DELETED_UPLOAD_RETENTION_HOURS: i64 = 24;
+
 /// Reset rows left in flight by a previous crashed instance. Run once on startup,
 /// before the HTTP server starts taking requests, so users never observe the
 /// half-state.
@@ -45,8 +83,23 @@ pub async fn startup_recovery(pool: &PgPool) {
         Err(e) => tracing::error!("startup recovery: failed to sweep uploads: {e:#}"),
     }
 
-    // Export jobs interrupted mid-run. Mark 'failed' so the host can re-trigger.
-    // The `UNIQUE(event_id, type)` constraint would otherwise block re-release.
+    // Export jobs interrupted mid-run are marked 'failed' here so they aren't left
+    // 'running' forever. The host CANNOT re-trigger a released export (release_gallery
+    // rejects an already-released event), so `export::recover_exports` re-spawns these
+    // failed-but-released jobs from `main` once `AppState` exists (it needs the media
+    // paths + SSE sender this fn doesn't have).
+    //
+    // SINGLE-INSTANCE ASSUMPTION: this sweep is unscoped — it reaps every `running` row, not just
+    // this process's. That is correct for the supported deployment (one app container; see
+    // docker-compose.yml), where no other process can own a job at boot. If EventSnap is ever run
+    // with more than one replica, a booting replica would mark a peer's live workers `failed`.
+    // This is NOT merely wasteful — do not assume the epoch model contains it. Recovery re-arms the
+    // job at the SAME epoch, so the reaped-but-still-alive worker and the fresh one would BOTH hold
+    // that epoch; the guards carry no owner/lease token, so they share the same artifact paths and
+    // either can win the other's `finalize_job`. That can corrupt or delete the keepsake. Running
+    // more than one replica therefore requires an owner/lease/heartbeat on export_job first. That
+    // machinery is not worth building for a single-container app — so this is a documented
+    // CONSTRAINT, not a hidden assumption: do not scale this service horizontally as-is.
     match sqlx::query(
         "UPDATE export_job
          SET status = 'failed',
@@ -67,6 +120,19 @@ pub async fn startup_recovery(pool: &PgPool) {
     }
 }
 
+/// How long a file in `originals/` may exist without a database row before it is treated as
+/// abandoned.
+///
+/// This window is the ONLY thing making the sweep safe, because the upload handler renames the
+/// temp file into its final path BEFORE committing the row: for a short moment a perfectly
+/// healthy upload legitimately looks exactly like an orphan. Six hours is far beyond any live
+/// request (a 576 MiB body over a bad venue uplink is minutes, and the request itself is bounded
+/// by the reverse proxy) while still reclaiming the leak inside a single event.
+///
+/// DO NOT SHORTEN THIS to make a test faster — a value below the longest possible in-flight
+/// upload deletes photos out from under the request that is committing them.
+const ORPHAN_UPLOAD_RETENTION_HOURS: u64 = 6;
+
 /// Spawns a background task that periodically:
 /// - deletes session rows whose `expires_at` is more than a day in the past
 /// - prunes the in-memory rate-limiter HashMap of empty windows
@@ -79,22 +145,247 @@ pub fn spawn_periodic_tasks(
     sse_tickets: SseTicketStore,
     media_path: PathBuf,
 ) {
+    // Supervised, because this one task carries EVERY piece of recurring hygiene in the app:
+    // session pruning, media reclamation, the orphan-temp sweep, and the rate-limiter and
+    // SSE-ticket maps. As a bare `tokio::spawn` with no retained handle, a single panic anywhere
+    // inside it stopped all five permanently and silently — no log line, no symptom until the
+    // disk or a HashMap grew into one. The supervisor re-spawns and, just as importantly, says
+    // so; it can never spin hot because the inner loop only returns by dying.
     tokio::spawn(async move {
-        let mut tick = tokio::time::interval(Duration::from_secs(3600));
-        // Fire the first tick immediately, then hourly.
-        tick.tick().await;
         loop {
-            tick.tick().await;
-            cleanup_sessions(&pool).await;
-            rate_limiter.prune();
-            sse_tickets.prune();
-            // Reclaim disk for uploads soft-deleted more than the grace period
-            // ago, and hard-delete those rows (FKs cascade).
-            crate::services::media_fs::reap_deleted(&pool, &media_path).await;
+            let inner = tokio::spawn(periodic_loop(
+                pool.clone(),
+                rate_limiter.clone(),
+                sse_tickets.clone(),
+                media_path.clone(),
+            ));
+            match inner.await {
+                Ok(()) => tracing::error!("periodic maintenance loop returned; restarting it"),
+                Err(e) => {
+                    tracing::error!(error = ?e, "periodic maintenance task died; restarting it")
+                }
+            }
+            tokio::time::sleep(Duration::from_secs(60)).await;
         }
     });
 }
 
+/// The actual hygiene loop. Never returns in normal operation — see the supervisor above.
+async fn periodic_loop(
+    pool: PgPool,
+    rate_limiter: RateLimiter,
+    sse_tickets: SseTicketStore,
+    media_path: PathBuf,
+) {
+    // A crash left whatever the previous process was mid-upload behind, and the first periodic
+    // tick is an hour away — sweep once up front so a restart is also a cleanup.
+    sweep_orphan_upload_temps(&media_path).await;
+
+    let mut tick = tokio::time::interval(Duration::from_secs(3600));
+    // Fire the first tick immediately, then hourly.
+    tick.tick().await;
+    loop {
+        tick.tick().await;
+        cleanup_sessions(&pool).await;
+        cleanup_deleted_media(&pool, &media_path).await;
+        sweep_orphan_upload_temps(&media_path).await;
+        // Runs AFTER the .tmp sweep, and covers the class that one structurally cannot see:
+        // an original that was renamed to its final name but whose transaction never
+        // committed. Those have no row, so `cleanup_deleted_media` (row-driven) can never
+        // find them, and `sweep_orphan_upload_temps` skips them because they no longer end
+        // in `.tmp` — they were permanently unowned, silently shrinking the free disk that
+        // `compute_storage_quota` divides among guests.
+        sweep_orphan_originals(&pool, &media_path).await;
+        rate_limiter.prune();
+        sse_tickets.prune();
+    }
+}
+
+/// How long an upload's `.tmp` file must have been untouched before it is treated as abandoned.
+///
+/// This is an age on the MODIFICATION time, not on creation, and that is what makes an hour
+/// safe rather than reckless: a live upload is being written to continuously, so its mtime keeps
+/// advancing and it can never age into the sweep no matter how slow the connection. The clock
+/// only starts once the writer stops — i.e. once the upload is genuinely dead.
+const ORPHAN_TEMP_MAX_AGE: Duration = Duration::from_secs(3600);
+
+/// Reclaim `.tmp` files left in the media tree by uploads that never finished.
+///
+/// `stream_field_to_file` removes its temp file on every error return, which covers everything
+/// the handler can see. It cannot cover the case that actually happens at a party: the client
+/// simply goes away — a phone sleeps, a guest walks out of range, the PWA is evicted mid-video —
+/// and axum DROPS the handler future rather than returning an error, so no cleanup code runs at
+/// all. The shutdown backstop force-exits in-flight handlers for the same net effect.
+///
+/// Nothing else reclaims these. `cleanup_deleted_media` only visits rows with `deleted_at`, and
+/// an abandoned upload never got a row; `export::sweep_orphan_temps` is only ever pointed at the
+/// exports volume. So before this, every abandonment stranded up to `max_video_size_mb` of
+/// unowned bytes permanently — and worse than merely leaking, they were subtracted from what
+/// everyone else could upload, because the per-user quota is computed from live free disk
+/// (`compute_storage_quota`). On a 40 GB disk shared with `postgres_data`, an evening of flaky
+/// venue wifi could take the event down.
+async fn sweep_orphan_upload_temps(media_path: &std::path::Path) {
+    let originals = media_path.join("originals");
+    let mut event_dirs = match tokio::fs::read_dir(&originals).await {
+        Ok(d) => d,
+        // Absent before the first upload — not a problem worth logging every hour.
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => return,
+        Err(e) => {
+            tracing::warn!(error = ?e, path = %originals.display(), "orphan temp sweep: unreadable");
+            return;
+        }
+    };
+
+    let mut reclaimed = 0usize;
+    let mut bytes = 0u64;
+    while let Ok(Some(event_dir)) = event_dirs.next_entry().await {
+        let Ok(mut files) = tokio::fs::read_dir(event_dir.path()).await else {
+            continue;
+        };
+        while let Ok(Some(file)) = files.next_entry().await {
+            let path = file.path();
+            if path.extension().is_none_or(|e| e != "tmp") {
+                continue;
+            }
+            let Ok(meta) = file.metadata().await else {
+                continue;
+            };
+            // No mtime (or a clock that moved backwards) means we cannot show the file is
+            // abandoned, and deleting a live upload is far worse than leaking one temp file.
+            let abandoned = meta
+                .modified()
+                .ok()
+                .and_then(|m| m.elapsed().ok())
+                .is_some_and(|age| age >= ORPHAN_TEMP_MAX_AGE);
+            if !abandoned {
+                continue;
+            }
+            match tokio::fs::remove_file(&path).await {
+                Ok(()) => {
+                    reclaimed += 1;
+                    bytes += meta.len();
+                }
+                Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+                Err(e) => {
+                    tracing::warn!(error = ?e, path = %path.display(),
+                        "orphan temp sweep: could not reclaim")
+                }
+            }
+        }
+    }
+
+    if reclaimed > 0 {
+        tracing::info!(
+            "orphan temp sweep: reclaimed {reclaimed} abandoned upload temp file(s), {} MiB",
+            bytes / (1024 * 1024)
+        );
+    }
+}
+
+/// Reclaim the media of soft-deleted uploads once they are past their retention window.
+///
+/// ONLY ever touches rows with `deleted_at IS NOT NULL`, so it can never reach a live upload. Two
+/// classes, two windows, because the two deletes mean different things:
+///
+/// - a compression failure the guest didn't ask for and may want investigated —
+///   [`FAILED_ORIGINAL_RETENTION_DAYS`];
+/// - a deliberate removal by the guest or the host — [`DELETED_UPLOAD_RETENTION_HOURS`].
+///
+/// ALL FOUR paths are reclaimed, not just the original. The previous version cleared
+/// `original_path` alone, which was right for its only case (a failed compression produces no
+/// derivatives) but wrong the moment the sweep reaches a successfully processed upload: preview,
+/// display and thumbnail are each a separate file on disk, none of them counted in
+/// `original_size_bytes`, and nothing else ever removed them.
+///
+/// Every column is cleared in the same pass, which makes the sweep idempotent and stops a later run
+/// re-reporting files that are already gone. The ROW is kept: it is the audit trail, it costs a few
+/// hundred bytes, and `backfill_stale_derivatives` is guarded on `deleted_at IS NULL` so a nulled
+/// `preview_path` can never make it regenerate what was just reclaimed.
+async fn cleanup_deleted_media(pool: &PgPool, media_path: &std::path::Path) {
+    type Row = (
+        uuid::Uuid,
+        String,
+        Option<String>,
+        Option<String>,
+        Option<String>,
+    );
+    let rows = sqlx::query_as::<_, Row>(
+        "SELECT id, original_path, preview_path, display_path, thumbnail_path FROM upload
+         WHERE deleted_at IS NOT NULL
+           AND CASE WHEN compression_status = 'failed'
+                    THEN deleted_at < NOW() - ($1 || ' days')::interval
+                    ELSE deleted_at < NOW() - ($2 || ' hours')::interval
+               END
+           AND (original_path <> '' OR preview_path IS NOT NULL
+                OR display_path IS NOT NULL OR thumbnail_path IS NOT NULL)",
+    )
+    .bind(FAILED_ORIGINAL_RETENTION_DAYS.to_string())
+    .bind(DELETED_UPLOAD_RETENTION_HOURS.to_string())
+    .fetch_all(pool)
+    .await;
+
+    let rows = match rows {
+        Ok(r) => r,
+        Err(e) => {
+            tracing::warn!(error = ?e, "deleted-media sweep query failed");
+            return;
+        }
+    };
+    if rows.is_empty() {
+        return;
+    }
+
+    let mut reclaimed = 0usize;
+    for (id, original, preview, display, thumbnail) in rows {
+        let paths: Vec<String> = std::iter::once(original)
+            .filter(|p| !p.is_empty())
+            .chain([preview, display, thumbnail].into_iter().flatten())
+            .collect();
+
+        // All-or-nothing per row: the columns are only cleared once every file for that upload is
+        // gone. Clearing after a partial success would strand the survivors with nothing pointing
+        // at them — the same unowned-bytes state this sweep exists to drain.
+        let mut all_gone = true;
+        for rel in &paths {
+            let absolute = media_path.join(rel);
+            match tokio::fs::remove_file(&absolute).await {
+                Ok(()) => reclaimed += 1,
+                // Already gone (manual cleanup, restored backup) — still counts as reclaimed for
+                // the purpose of clearing the columns, or the row is re-selected every hour forever.
+                Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+                Err(e) => {
+                    tracing::warn!(error = ?e, %id, path = %absolute.display(),
+                        "could not reclaim deleted media; leaving the row for the next sweep");
+                    all_gone = false;
+                }
+            }
+        }
+        if !all_gone {
+            continue;
+        }
+
+        if let Err(e) = sqlx::query(
+            "UPDATE upload SET original_path = '', preview_path = NULL,
+                    display_path = NULL, thumbnail_path = NULL
+             WHERE id = $1",
+        )
+        .bind(id)
+        .execute(pool)
+        .await
+        {
+            tracing::warn!(error = ?e, %id, "reclaimed the files but could not clear the paths");
+        }
+    }
+
+    if reclaimed > 0 {
+        tracing::info!(
+            "reclaimed {reclaimed} file(s) from soft-deleted uploads (deliberate deletes after \
+             {DELETED_UPLOAD_RETENTION_HOURS}h, compression failures after \
+             {FAILED_ORIGINAL_RETENTION_DAYS}d)"
+        );
+    }
+}
+
 async fn cleanup_sessions(pool: &PgPool) {
     match sqlx::query("DELETE FROM session WHERE expires_at < NOW() - INTERVAL '1 day'")
         .execute(pool)
@@ -107,3 +398,192 @@ async fn cleanup_sessions(pool: &PgPool) {
         Err(e) => tracing::warn!("session cleanup failed: {e:#}"),
     }
 }
+
+/// Reclaim files in `originals/` that no upload row references.
+///
+/// The backstop behind [`TempFileGuard`](crate::handlers::upload). The guard covers the
+/// process that is running; this covers the process that was killed — a SIGKILL, an OOM, or a
+/// power cut leaves whatever bytes had been written with no `Drop` to reclaim them, and those
+/// files are then permanently invisible: they have no row, so `cleanup_deleted_media` (which is
+/// row-driven) can never see them, and they are not counted against any quota while still
+/// consuming the free disk that `compute_storage_quota` divides among guests. On a single box
+/// where all three volumes share a filesystem, that ends with Postgres unable to write WAL.
+///
+/// Two classes:
+/// - `*.tmp` — an upload that never got as far as being renamed. Always safe past the window.
+/// - everything else — a final-named original whose commit never happened.
+async fn sweep_orphan_originals(pool: &PgPool, media_path: &std::path::Path) {
+    let originals = media_path.join("originals");
+    let cutoff = Duration::from_secs(ORPHAN_UPLOAD_RETENTION_HOURS * 3600);
+
+    // originals/{event_slug}/{uuid}.{ext} — one level of per-event directories.
+    let mut event_dirs = match tokio::fs::read_dir(&originals).await {
+        Ok(rd) => rd,
+        // Nothing uploaded yet; the directory is created lazily by the upload handler.
+        Err(_) => return,
+    };
+
+    let mut candidates: Vec<(String, std::path::PathBuf)> = Vec::new();
+    let mut temps_removed = 0u32;
+
+    while let Ok(Some(event_dir)) = event_dirs.next_entry().await {
+        if !event_dir
+            .file_type()
+            .await
+            .map(|t| t.is_dir())
+            .unwrap_or(false)
+        {
+            continue;
+        }
+        let slug = event_dir.file_name().to_string_lossy().to_string();
+        let Ok(mut files) = tokio::fs::read_dir(event_dir.path()).await else {
+            continue;
+        };
+        while let Ok(Some(entry)) = files.next_entry().await {
+            let Ok(meta) = entry.metadata().await else {
+                continue;
+            };
+            if !meta.is_file() {
+                continue;
+            }
+            // Too young to judge: an upload committing RIGHT NOW is indistinguishable from an
+            // orphan, because the rename precedes the commit.
+            let recent = meta
+                .modified()
+                .ok()
+                .and_then(|m| m.elapsed().ok())
+                .is_none_or(|age| age < cutoff);
+            if recent {
+                continue;
+            }
+
+            let name = entry.file_name().to_string_lossy().to_string();
+            if name.ends_with(".tmp") {
+                // A `.tmp` never has a row by construction — no DB check needed.
+                if tokio::fs::remove_file(entry.path()).await.is_ok() {
+                    temps_removed += 1;
+                }
+                continue;
+            }
+            candidates.push((format!("originals/{slug}/{name}"), entry.path()));
+        }
+    }
+
+    if temps_removed > 0 {
+        tracing::warn!(
+            "reclaimed {temps_removed} abandoned upload temp file(s) older than \
+             {ORPHAN_UPLOAD_RETENTION_HOURS}h"
+        );
+    }
+    if candidates.is_empty() {
+        return;
+    }
+
+    // One query per batch, not one per file: a backlog of thousands of orphans must not turn
+    // into thousands of round trips on an hourly timer.
+    let mut orphans_removed = 0u32;
+    for chunk in candidates.chunks(500) {
+        let paths: Vec<String> = chunk.iter().map(|(rel, _)| rel.clone()).collect();
+        // NO `deleted_at IS NULL` FILTER HERE. A soft-deleted row still points at its file
+        // during its retention window, and reclaiming that file is `cleanup_deleted_media`'s
+        // job — filtering here would race the two sweeps and destroy the exact files the
+        // recovery window exists to preserve.
+        let unreferenced: Result<Vec<(String,)>, _> = sqlx::query_as(
+            "SELECT p FROM unnest($1::text[]) AS p
+              WHERE NOT EXISTS (SELECT 1 FROM upload u WHERE u.original_path = p)",
+        )
+        .bind(&paths)
+        .fetch_all(pool)
+        .await;
+        let unreferenced = match unreferenced {
+            Ok(rows) => rows,
+            Err(e) => {
+                tracing::warn!(error = ?e, "orphan-original sweep query failed");
+                return;
+            }
+        };
+        for (rel,) in unreferenced {
+            if let Some((_, abs)) = chunk.iter().find(|(r, _)| *r == rel)
+                && tokio::fs::remove_file(abs).await.is_ok()
+            {
+                orphans_removed += 1;
+            }
+        }
+    }
+
+    if orphans_removed > 0 {
+        tracing::warn!(
+            "reclaimed {orphans_removed} original(s) with no upload row, older than \
+             {ORPHAN_UPLOAD_RETENTION_HOURS}h"
+        );
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Build `<root>/originals/<event>/<name>` with `len` bytes, optionally back-dating its mtime
+    /// by `age`. Back-dating is the only way to test the sweep without sleeping through an hour.
+    fn temp_file(root: &std::path::Path, name: &str, len: usize, age: Option<Duration>) {
+        let dir = root.join("originals").join("wedding");
+        std::fs::create_dir_all(&dir).expect("create dir");
+        let path = dir.join(name);
+        let f = std::fs::File::create(&path).expect("create file");
+        std::io::Write::write_all(&mut &f, &vec![0u8; len]).expect("write");
+        if let Some(age) = age {
+            let when = std::time::SystemTime::now() - age;
+            f.set_modified(when).expect("set mtime");
+        }
+    }
+
+    fn exists(root: &std::path::Path, name: &str) -> bool {
+        root.join("originals").join("wedding").join(name).exists()
+    }
+
+    /// The two halves of the guarantee in one pass: an abandoned temp is reclaimed, and a temp
+    /// that is still being written to is NOT — the second matters more, because deleting a live
+    /// upload's temp file would corrupt a photo that was about to succeed.
+    #[tokio::test]
+    async fn the_sweep_reclaims_abandoned_temps_and_spares_live_ones() {
+        let root = std::env::temp_dir().join(format!("es-sweep-{}", uuid::Uuid::new_v4()));
+
+        // Abandoned: the writer died over an hour ago and nothing has touched it since.
+        temp_file(
+            &root,
+            "dead.tmp",
+            2048,
+            Some(ORPHAN_TEMP_MAX_AGE + Duration::from_secs(60)),
+        );
+        // Live: an upload in progress keeps advancing its mtime, so it always looks young —
+        // this is why the threshold is on modification time and not on creation time.
+        temp_file(&root, "inflight.tmp", 2048, None);
+        // A committed original. The sweep must only ever consider `.tmp`.
+        temp_file(&root, "keeper.jpg", 2048, Some(Duration::from_secs(86_400)));
+
+        sweep_orphan_upload_temps(&root).await;
+
+        assert!(
+            !exists(&root, "dead.tmp"),
+            "an abandoned temp must be reclaimed"
+        );
+        assert!(
+            exists(&root, "inflight.tmp"),
+            "a temp still being written to must survive — deleting it destroys a live upload"
+        );
+        assert!(
+            exists(&root, "keeper.jpg"),
+            "the sweep must never touch a committed original"
+        );
+
+        let _ = std::fs::remove_dir_all(&root);
+    }
+
+    /// Runs on every boot and every hour, so a media tree that does not exist yet (before the
+    /// first upload) must be a silent no-op rather than an error logged 24 times a day.
+    #[tokio::test]
+    async fn a_missing_media_tree_is_not_an_error() {
+        let root = std::env::temp_dir().join(format!("es-sweep-absent-{}", uuid::Uuid::new_v4()));
+        sweep_orphan_upload_temps(&root).await; // must simply return
+    }
+}

backend/src/services/media_fs.rs

@@ -1,83 +0,0 @@
-//! Filesystem lifecycle for media artifacts.
-//!
-//! The DB-aware gateway hides deleted/hidden uploads, but the bytes still sit on
-//! a fixed-size disk until something removes them. This module is that
-//! something: best-effort unlinking on delete, plus a periodic reaper that
-//! sweeps files belonging to soft-deleted rows (catching anything an in-process
-//! unlink missed — e.g. a crash between the DB commit and the unlink).
-
-use std::path::Path;
-
-use sqlx::PgPool;
-
-use crate::models::upload::DeletedPaths;
-
-/// Best-effort removal of an upload's three on-disk artifacts. A missing file is
-/// not an error (it may already be gone, or never existed for videos without a
-/// preview); anything else is logged but never propagated — losing the bytes
-/// must not fail the user's delete.
-pub async fn unlink_media(media_path: &Path, paths: &DeletedPaths) {
-    let candidates = [
-        Some(&paths.original),
-        paths.preview.as_ref(),
-        paths.thumbnail.as_ref(),
-    ];
-    for rel in candidates.into_iter().flatten() {
-        let abs = media_path.join(rel);
-        match tokio::fs::remove_file(&abs).await {
-            Ok(()) => {}
-            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
-            Err(e) => tracing::warn!(path = %rel, error = ?e, "media unlink failed"),
-        }
-    }
-}
-
-/// Reaper: remove on-disk files for uploads that were soft-deleted more than
-/// `grace` ago, then hard-delete those rows so they don't accumulate. Strictly
-/// DB-row-driven — it never walks the filesystem, so it can never remove a file
-/// belonging to a live upload.
-pub async fn reap_deleted(pool: &PgPool, media_path: &Path) {
-    // Snapshot the exact rows (id + paths) we are about to unlink, and delete by
-    // those ids — NOT by re-evaluating the `deleted_at < now - 1 day` predicate.
-    // A row that crosses the 1-day line *during* the unlink loop would otherwise
-    // be hard-deleted by the second predicate without ever having its files
-    // unlinked → a permanent orphan.
-    let rows: Vec<(uuid::Uuid, String, Option<String>, Option<String>)> = match sqlx::query_as(
-        "SELECT id, original_path, preview_path, thumbnail_path
-         FROM upload
-         WHERE deleted_at IS NOT NULL AND deleted_at < NOW() - INTERVAL '1 day'",
-    )
-    .fetch_all(pool)
-    .await
-    {
-        Ok(rows) => rows,
-        Err(e) => {
-            tracing::warn!(error = ?e, "media reaper: query failed");
-            return;
-        }
-    };
-
-    if rows.is_empty() {
-        return;
-    }
-
-    let mut ids = Vec::with_capacity(rows.len());
-    for (id, original, preview, thumbnail) in &rows {
-        unlink_media(media_path, &DeletedPaths {
-            original: original.clone(),
-            preview: preview.clone(),
-            thumbnail: thumbnail.clone(),
-        })
-        .await;
-        ids.push(*id);
-    }
-
-    match sqlx::query("DELETE FROM upload WHERE id = ANY($1)")
-        .bind(&ids)
-        .execute(pool)
-        .await
-    {
-        Ok(r) => tracing::info!("media reaper: removed {} deleted upload(s)", r.rows_affected()),
-        Err(e) => tracing::warn!(error = ?e, "media reaper: row delete failed"),
-    }
-}

backend/src/services/media_token.rs

@@ -1,122 +0,0 @@
-//! Stateless signed URLs for the authenticated media gateway.
-//!
-//! Media (`<img>`/`<video>` sources) cannot carry an `Authorization` header, so
-//! access is granted by an HMAC-SHA256 signature embedded in the URL. The
-//! feed/upload DTOs are serialized for an already-authenticated event member, so
-//! that is where fresh signatures are minted; the gateway handler verifies them
-//! without any DB/session state.
-//!
-//! HMAC is implemented over the in-tree `sha2` crate (no new dependency). The
-//! key is the app's `jwt_secret`.
-
-use sha2::{Digest, Sha256};
-use uuid::Uuid;
-
-/// Validity window of a signed URL.
-const TTL_SECS: i64 = 24 * 3600;
-/// Issue-time bucket. Expiry (and therefore the URL) is stable within this
-/// window so the browser caches image bytes across feed polls instead of
-/// re-downloading on every refresh.
-const BUCKET_SECS: i64 = 3600;
-
-fn hmac_sha256(key: &[u8], msg: &[u8]) -> [u8; 32] {
-    const BLOCK: usize = 64;
-    let mut key_block = [0u8; BLOCK];
-    if key.len() > BLOCK {
-        let digest = Sha256::digest(key);
-        key_block[..32].copy_from_slice(&digest);
-    } else {
-        key_block[..key.len()].copy_from_slice(key);
-    }
-
-    let mut ipad = [0x36u8; BLOCK];
-    let mut opad = [0x5cu8; BLOCK];
-    for i in 0..BLOCK {
-        ipad[i] ^= key_block[i];
-        opad[i] ^= key_block[i];
-    }
-
-    let mut inner = Sha256::new();
-    inner.update(ipad);
-    inner.update(msg);
-    let inner_digest = inner.finalize();
-
-    let mut outer = Sha256::new();
-    outer.update(opad);
-    outer.update(inner_digest);
-    outer.finalize().into()
-}
-
-fn sign(secret: &str, kind: &str, id: Uuid, exp: i64) -> String {
-    let msg = format!("{kind}:{id}:{exp}");
-    let mac = hmac_sha256(secret.as_bytes(), msg.as_bytes());
-    let mut hex = String::with_capacity(64);
-    for b in mac {
-        use std::fmt::Write;
-        let _ = write!(hex, "{b:02x}");
-    }
-    hex
-}
-
-/// Build a signed, time-boxed gateway URL for one of an upload's artifacts.
-/// `kind` is `original` | `preview` | `thumbnail`.
-pub fn signed_url(secret: &str, kind: &str, id: Uuid, now: i64) -> String {
-    let exp = ((now / BUCKET_SECS) * BUCKET_SECS) + TTL_SECS;
-    let sig = sign(secret, kind, id, exp);
-    format!("/media/{kind}/{id}?exp={exp}&sig={sig}")
-}
-
-/// Verify a signed URL: signature must match and the expiry must not have
-/// passed. Signature comparison is constant-time.
-pub fn verify(secret: &str, kind: &str, id: Uuid, exp: i64, sig: &str, now: i64) -> bool {
-    if exp < now {
-        return false;
-    }
-    let expected = sign(secret, kind, id, exp);
-    constant_time_eq(expected.as_bytes(), sig.as_bytes())
-}
-
-fn constant_time_eq(a: &[u8], b: &[u8]) -> bool {
-    if a.len() != b.len() {
-        return false;
-    }
-    let mut diff = 0u8;
-    for (x, y) in a.iter().zip(b.iter()) {
-        diff |= x ^ y;
-    }
-    diff == 0
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn sign_verify_roundtrip() {
-        let secret = "test_secret_at_least_32_chars_long_xxxx";
-        let id = Uuid::new_v4();
-        let now = 1_700_000_000;
-        let url = signed_url(secret, "original", id, now);
-        // Extract exp + sig from the query string.
-        let (_, query) = url.split_once('?').unwrap();
-        let mut exp = 0i64;
-        let mut sig = String::new();
-        for pair in query.split('&') {
-            let (k, v) = pair.split_once('=').unwrap();
-            match k {
-                "exp" => exp = v.parse().unwrap(),
-                "sig" => sig = v.to_string(),
-                _ => {}
-            }
-        }
-        assert!(verify(secret, "original", id, exp, &sig, now));
-        // Tampered kind / id / sig must fail.
-        assert!(!verify(secret, "preview", id, exp, &sig, now));
-        assert!(!verify(secret, "original", Uuid::new_v4(), exp, &sig, now));
-        assert!(!verify(secret, "original", id, exp, "deadbeef", now));
-        // Wrong secret must fail.
-        assert!(!verify("other_secret_at_least_32_chars_long_yy", "original", id, exp, &sig, now));
-        // Expired must fail.
-        assert!(!verify(secret, "original", id, exp, &sig, exp + 1));
-    }
-}

backend/src/services/media_total.rs

@@ -0,0 +1,104 @@
+//! Cached sum of all media bytes the event is holding.
+//!
+//! The upload gate needs to know "how big would the keepsake be if we accept this file", because
+//! the archive needs room for BOTH halves at once (`export::required_free_bytes` is
+//! `media × 1.1 × 2` — the ZIP and the HTML viewer are each gallery-sized). Asking that question
+//! per upload has to be cheap, and it has to be cheap on the busiest write path in the app.
+//!
+//! `export::estimate_export_bytes` answers the same question exactly, but it aggregates
+//! `original_size_bytes` across every upload row joined to `user` — fine once per release,
+//! wasteful per upload and growing all evening. This sums `user.total_upload_bytes` instead:
+//! one row per guest (~100), already maintained transactionally by the quota path, already
+//! refunded on delete.
+//!
+//! The two differ slightly — this one counts uploads belonging to banned or hidden users, which
+//! the export filters out. That skew is in the SAFE direction: it over-estimates the archive, so
+//! the gate closes marginally early rather than marginally late. Never swap it for a cheaper
+//! query that could under-estimate; an under-estimate authorises the very upload that makes the
+//! keepsake unbuildable, which is the failure this exists to prevent.
+
+use std::sync::{Arc, RwLock};
+use std::time::{Duration, Instant};
+
+use sqlx::PgPool;
+
+/// How long a reading is trusted. Shorter than [`crate::services::disk`]'s TTL because this
+/// number only ever grows and does so in the same request path that reads it — a stale value
+/// under-counts the newest uploads, and under-counting is the direction that matters.
+const TTL: Duration = Duration::from_secs(5);
+
+/// Cheap-to-clone cache of the event's total media bytes. Lives in `AppState`.
+#[derive(Clone)]
+pub struct MediaTotalCache {
+    inner: Arc<RwLock<Option<(i64, Instant)>>>,
+}
+
+impl MediaTotalCache {
+    pub fn new() -> Self {
+        Self {
+            inner: Arc::new(RwLock::new(None)),
+        }
+    }
+
+    /// Drop the cached reading so the next `get()` re-queries.
+    ///
+    /// Used by the e2e TRUNCATE endpoint for the same reason `DiskCache::invalidate` exists:
+    /// truncation removes every upload, and a surviving reading would make the next test's
+    /// gate compute against the previous test's data.
+    pub fn invalidate(&self) {
+        *self.inner.write().unwrap() = None;
+    }
+
+    /// Total bytes of media the event is holding, cached for [`TTL`].
+    ///
+    /// Returns 0 when the query fails. That is a deliberate FAIL-OPEN, consistent with the
+    /// quota path and the export preflight: a database blip must not turn into "every upload
+    /// refused". The disk-space half of the gate still applies, so a failure here degrades the
+    /// check to the old flat-reserve behaviour rather than disabling it.
+    pub async fn get(&self, pool: &PgPool) -> i64 {
+        if let Some((bytes, at)) = *self.inner.read().unwrap()
+            && at.elapsed() < TTL
+        {
+            return bytes;
+        }
+        let queried = sqlx::query_scalar::<_, Option<i64>>(
+            "SELECT SUM(total_upload_bytes)::bigint FROM \"user\"",
+        )
+        .fetch_one(pool)
+        .await;
+
+        let bytes = match queried {
+            Ok(v) => v.unwrap_or(0).max(0),
+            Err(e) => {
+                // FAIL OPEN, but do NOT cache the failure, and do NOT let it pass silently.
+                //
+                // Storing 0 here pinned the gate's view of the event at "empty" for the whole
+                // TTL. During that window `media_after` is just this upload, `keepsake_needs`
+                // collapses to ~2.2x one file, and the gate degrades to the flat 10 GB reserve —
+                // precisely the behaviour the two-halves design replaced, reappearing with no
+                // trace in the log. And the trigger correlates with the danger: with
+                // `max_connections = 10` and a 5s acquire timeout, this query fails exactly when
+                // a burst is in progress.
+                //
+                // Falling back to the LAST GOOD reading (however stale) is strictly better than
+                // 0: the total only ever grows, so a stale value under-counts slightly, while 0
+                // under-counts by everything.
+                let previous = self.inner.read().unwrap().map(|(b, _)| b);
+                tracing::warn!(
+                    error = %e,
+                    fallback_bytes = previous.unwrap_or(0),
+                    "media total query failed; upload gate is running on a stale reading"
+                );
+                return previous.unwrap_or(0);
+            }
+        };
+        *self.inner.write().unwrap() = Some((bytes, Instant::now()));
+        bytes
+    }
+}
+
+impl Default for MediaTotalCache {
+    fn default() -> Self {
+        Self::new()
+    }
+}

backend/src/services/mod.rs

@@ -1,10 +1,11 @@
 pub mod compression;
 pub mod config;
+pub mod disk;
 pub mod export;
-pub mod jobs;
+pub mod imaging;
 pub mod maintenance;
-pub mod media_fs;
-pub mod media_token;
-pub mod password;
+pub mod media_total;
 pub mod rate_limiter;
 pub mod sse_tickets;
+pub mod upload_admission;
+pub mod video;

backend/src/services/password.rs

@@ -1,25 +0,0 @@
-//! bcrypt hashing/verification offloaded to the blocking pool.
-//!
-//! bcrypt cost-12 is ~250–400ms of synchronous CPU. Called directly in an async
-//! handler it pins a Tokio worker for that whole time, so a handful of
-//! concurrent joins/recovers/admin-logins can starve every other request
-//! (feed, SSE, upload). Routing the work through `spawn_blocking` keeps the
-//! async reactor responsive.
-
-use crate::error::AppError;
-
-/// Hash a secret with the given bcrypt cost, off the async reactor.
-pub async fn hash(plain: String, cost: u32) -> Result<String, AppError> {
-    tokio::task::spawn_blocking(move || bcrypt::hash(&plain, cost))
-        .await
-        .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))?
-        .map_err(|e| AppError::Internal(anyhow::anyhow!(e)))
-}
-
-/// Verify a secret against a bcrypt hash, off the async reactor. Returns `false`
-/// on any error (mirrors the previous `unwrap_or(false)` fail-closed behavior).
-pub async fn verify(plain: String, hash: String) -> bool {
-    tokio::task::spawn_blocking(move || bcrypt::verify(&plain, &hash).unwrap_or(false))
-        .await
-        .unwrap_or(false)
-}

backend/src/services/rate_limiter.rs

@@ -17,14 +17,20 @@ impl RateLimiter {
         }
     }
 
-    /// Returns `true` if the request is allowed, `false` if rate-limited.
-    pub fn check(&self, key: impl Into<String>, max: usize, window: Duration) -> bool {
-        self.check_with_retry(key, max, window).is_ok()
-    }
-
     /// Returns `Ok(())` if allowed, `Err(retry_after_secs)` if rate-limited.
     /// `retry_after_secs` is how long until the oldest slot in the window expires.
-    pub fn check_with_retry(&self, key: impl Into<String>, max: usize, window: Duration) -> Result<(), u64> {
+    ///
+    /// This is deliberately the ONLY entry point. There used to be a `check()` wrapper
+    /// returning a plain bool, and 7 of the 8 call sites used it and then hard-coded
+    /// `None` for the response's `Retry-After` — so a throttled client was told to back
+    /// off but never for how long. Forcing every caller through the `Result` makes the
+    /// retry delay impossible to discard by accident.
+    pub fn check_with_retry(
+        &self,
+        key: impl Into<String>,
+        max: usize,
+        window: Duration,
+    ) -> Result<(), u64> {
         let now = Instant::now();
         let key = key.into();
         let mut map = self.windows.lock().unwrap();
@@ -34,8 +40,18 @@ impl RateLimiter {
             timestamps.push(now);
             Ok(())
         } else {
-            // The oldest timestamp expires at oldest + window; compute remaining seconds
-            let oldest = timestamps[0];
+            // The oldest timestamp expires at oldest + window; compute remaining seconds.
+            //
+            // `first()`, not `[0]`: with `max == 0` the length check above is false even on an
+            // empty vec, so indexing would panic — WHILE HOLDING THIS MUTEX. That poisons it
+            // process-wide, so every subsequent `.lock().unwrap()` panics too: upload, feed,
+            // join, recover, social, export and the hourly maintenance task all die, and only
+            // a container restart brings them back. `max == 0` is not reachable through the
+            // admin API (every numeric spec has min = 1) but a direct DB edit would do it, and
+            // the blast radius does not justify the sharper syntax.
+            let Some(&oldest) = timestamps.first() else {
+                return Ok(());
+            };
             let elapsed = now.duration_since(oldest);
             let remaining = window.saturating_sub(elapsed);
             Err(remaining.as_secs().max(1))
@@ -71,27 +87,24 @@ impl RateLimiter {
     }
 }
 
-/// Extract the client IP for rate-limit keys.
+/// Extract the client IP from X-Forwarded-For or fall back to a provided socket
+/// address string.
 ///
-/// Prefers `X-Real-IP`, which our reverse proxy (Caddy) overwrites with the real
-/// TCP peer (`header_up X-Real-IP {remote_host}`) — a client cannot spoof it.
-/// Falls back to the **rightmost** `X-Forwarded-For` token (the entry the proxy
-/// appended), never the leftmost: the leftmost is fully client-controlled, and
-/// trusting it let an attacker rotate the key to bypass the join cap, the
-/// recover throttle, and the admin-login floor.
+/// We take the **right-most** entry, not the left-most. Caddy is the sole ingress
+/// and the app port is only `expose`d (never published), so the last hop Caddy
+/// appends is the real client. A client can prepend arbitrary spoofed values to
+/// the left of XFF to dodge throttles — those are ignored here. This assumes
+/// exactly one trusted proxy (Caddy); revisit if that changes.
+///
+/// Pass the peer address as `fallback`, never a constant. Every caller used to pass
+/// the literal `"unknown"`, so any request that arrived without XFF — i.e. anything
+/// reaching the app directly rather than through Caddy — shared ONE bucket with every
+/// other such request, turning the limiter into a self-inflicted global throttle.
 pub fn client_ip(headers: &axum::http::HeaderMap, fallback: &str) -> String {
-    if let Some(ip) = headers
-        .get("x-real-ip")
-        .and_then(|v| v.to_str().ok())
-        .map(|s| s.trim())
-        .filter(|s| !s.is_empty())
-    {
-        return ip.to_owned();
-    }
     headers
         .get("x-forwarded-for")
         .and_then(|v| v.to_str().ok())
-        .and_then(|s| s.split(',').next_back())
+        .and_then(|s| s.rsplit(',').next())
         .map(|s| s.trim().to_owned())
         .filter(|s| !s.is_empty())
         .unwrap_or_else(|| fallback.to_owned())
@@ -99,27 +112,207 @@ pub fn client_ip(headers: &axum::http::HeaderMap, fallback: &str) -> String {
 
 #[cfg(test)]
 mod tests {
-    use super::client_ip;
+    use super::*;
     use axum::http::HeaderMap;
 
+    const MIN: Duration = Duration::from_secs(60);
+
     #[test]
-    fn prefers_x_real_ip() {
-        let mut h = HeaderMap::new();
-        h.insert("x-real-ip", "9.9.9.9".parse().unwrap());
-        h.insert("x-forwarded-for", "1.1.1.1, 9.9.9.9".parse().unwrap());
-        assert_eq!(client_ip(&h, "fb"), "9.9.9.9");
+    fn allows_up_to_max_then_blocks() {
+        let rl = RateLimiter::new();
+        assert!(rl.check_with_retry("k", 3, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 3, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 3, MIN).is_ok());
+        assert!(
+            rl.check_with_retry("k", 3, MIN).is_err(),
+            "the 4th request must be blocked"
+        );
     }
 
     #[test]
-    fn xff_uses_rightmost_not_spoofable_leftmost() {
-        // Attacker prepends a forged entry; the proxy-appended real peer is last.
-        let mut h = HeaderMap::new();
-        h.insert("x-forwarded-for", "1.2.3.4, 203.0.113.7".parse().unwrap());
-        assert_eq!(client_ip(&h, "fb"), "203.0.113.7");
+    fn keys_are_independent() {
+        let rl = RateLimiter::new();
+        assert!(rl.check_with_retry("a", 1, MIN).is_ok());
+        assert!(rl.check_with_retry("a", 1, MIN).is_err());
+        assert!(
+            rl.check_with_retry("b", 1, MIN).is_ok(),
+            "a different key has its own window"
+        );
     }
 
     #[test]
-    fn falls_back_when_no_headers() {
-        assert_eq!(client_ip(&HeaderMap::new(), "fb"), "fb");
+    fn window_slides_and_allows_again_after_expiry() {
+        let rl = RateLimiter::new();
+        let w = Duration::from_millis(40);
+        assert!(rl.check_with_retry("k", 1, w).is_ok());
+        assert!(rl.check_with_retry("k", 1, w).is_err());
+        std::thread::sleep(Duration::from_millis(55));
+        assert!(
+            rl.check_with_retry("k", 1, w).is_ok(),
+            "the slot should expire once the window passes"
+        );
+    }
+
+    /// `retry_after` is not a "some number in range" — it is the time until the oldest slot
+    /// in the window frees up, and it is surfaced to clients as the backoff they sleep for
+    /// (see `upload-queue.ts`). Asserting only `(1..=60)` spans the entire reachable domain
+    /// of a 60s window, so a hardcoded `Err(1)` would satisfy it while telling every client
+    /// to hammer the server a second later. Pin the actual value.
+    #[test]
+    fn retry_after_is_the_remaining_window() {
+        let rl = RateLimiter::new();
+
+        // The slot was consumed just now, so essentially the whole window remains.
+        // `as_secs()` truncates the sub-second remainder, so a 30s window reports 29.
+        let w30 = Duration::from_secs(30);
+        assert!(rl.check_with_retry("a", 1, w30).is_ok());
+        let a = rl.check_with_retry("a", 1, w30).unwrap_err();
+        assert_eq!(a, 29, "retry_after must be the remaining window, got {a}");
+
+        // A different window must yield a different retry_after: no single constant can
+        // satisfy both this and the assertion above.
+        let w10 = Duration::from_secs(10);
+        assert!(rl.check_with_retry("b", 1, w10).is_ok());
+        let b = rl.check_with_retry("b", 1, w10).unwrap_err();
+        assert_eq!(b, 9, "retry_after must scale with the window, got {b}");
+    }
+
+    #[test]
+    fn retry_after_counts_down_as_the_window_elapses() {
+        let rl = RateLimiter::new();
+        let w = Duration::from_secs(30);
+        assert!(rl.check_with_retry("k", 1, w).is_ok());
+        let first = rl.check_with_retry("k", 1, w).unwrap_err();
+
+        std::thread::sleep(Duration::from_millis(1200));
+        let second = rl.check_with_retry("k", 1, w).unwrap_err();
+
+        // A client that waits 1.2s must be told to wait ~1.2s less — otherwise the advertised
+        // backoff is a constant, not a deadline.
+        let shaved = first - second;
+        assert!(
+            (1..=2).contains(&shaved),
+            "1.2s of waiting must shorten the advertised backoff by ~1s (got {first} then {second})"
+        );
+    }
+
+    #[test]
+    fn retry_after_floors_at_one_second() {
+        let rl = RateLimiter::new();
+        let w = Duration::from_millis(800);
+        assert!(rl.check_with_retry("k", 1, w).is_ok());
+        let retry = rl.check_with_retry("k", 1, w).unwrap_err();
+        // The sub-second remainder truncates to 0; clients must never be told "retry in 0s"
+        // (that's a busy-loop). The `.max(1)` floor is what prevents it.
+        assert_eq!(
+            retry, 1,
+            "a sub-second remainder must floor to 1, got {retry}"
+        );
+    }
+
+    #[test]
+    fn clear_resets_every_window() {
+        let rl = RateLimiter::new();
+        assert!(rl.check_with_retry("k", 1, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 1, MIN).is_err());
+        rl.clear();
+        assert!(
+            rl.check_with_retry("k", 1, MIN).is_ok(),
+            "clear() must free the window"
+        );
+    }
+
+    /// `prune()` is a memory-leak guard: without it a long-lived process keeps one HashMap
+    /// entry per IP that ever connected. Nothing in the public API observes the map size, so
+    /// the only way to catch a no-op body (`fn prune(&self) {}`) is to look at the map — the
+    /// tests module can see the private field.
+    #[test]
+    fn prune_drops_keys_whose_windows_have_fully_expired() {
+        let rl = RateLimiter::new();
+
+        // A key whose only timestamp is older than the 24h ceiling. We can't sleep for a day,
+        // so backdate the Instant directly.
+        let ancient = Instant::now()
+            .checked_sub(Duration::from_secs(25 * 60 * 60))
+            .expect("backdating an Instant by 25h");
+        rl.windows
+            .lock()
+            .unwrap()
+            .insert("stale".to_string(), vec![ancient]);
+
+        // ...alongside a key that is still inside its window.
+        assert!(rl.check_with_retry("live", 5, MIN).is_ok());
+        assert_eq!(rl.windows.lock().unwrap().len(), 2);
+
+        rl.prune();
+
+        let map = rl.windows.lock().unwrap();
+        assert!(
+            !map.contains_key("stale"),
+            "prune() must drop keys whose timestamps have all expired"
+        );
+        assert!(
+            map.contains_key("live"),
+            "prune() must keep keys that still have live timestamps"
+        );
+        assert_eq!(map.len(), 1, "exactly one key should survive the prune");
+    }
+
+    #[test]
+    fn prune_does_not_reset_a_live_window() {
+        // The counterpart to the test above: pruning must reclaim memory, never quota. If
+        // prune() dropped live keys, every background sweep would hand attackers a fresh
+        // budget.
+        let rl = RateLimiter::new();
+        assert!(rl.check_with_retry("k", 1, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 1, MIN).is_err());
+
+        rl.prune();
+
+        assert!(
+            rl.check_with_retry("k", 1, MIN).is_err(),
+            "prune() must not clear a window that is still active"
+        );
+    }
+
+    #[test]
+    fn client_ip_takes_rightmost_forwarded_for_entry() {
+        // The right-most entry is the hop our trusted proxy (Caddy) appended.
+        let mut h = HeaderMap::new();
+        h.insert("x-forwarded-for", "10.0.0.1, 203.0.113.7".parse().unwrap());
+        assert_eq!(client_ip(&h, "fallback"), "203.0.113.7");
+    }
+
+    #[test]
+    fn client_ip_ignores_spoofed_leftmost_entry() {
+        // A client prepending a fake IP to dodge throttles must not win.
+        let mut h = HeaderMap::new();
+        h.insert(
+            "x-forwarded-for",
+            "1.2.3.4, 9.9.9.9, 203.0.113.7".parse().unwrap(),
+        );
+        assert_eq!(client_ip(&h, "fallback"), "203.0.113.7");
+    }
+
+    #[test]
+    fn client_ip_trims_surrounding_whitespace() {
+        let mut h = HeaderMap::new();
+        h.insert("x-forwarded-for", "  198.51.100.5  ".parse().unwrap());
+        assert_eq!(client_ip(&h, "fb"), "198.51.100.5");
+    }
+
+    #[test]
+    fn client_ip_falls_back_when_header_absent() {
+        assert_eq!(client_ip(&HeaderMap::new(), "127.0.0.1"), "127.0.0.1");
+    }
+
+    #[test]
+    fn client_ip_falls_back_on_trailing_comma_empty_entry() {
+        // A trailing comma leaves an empty right-most segment after trimming; the
+        // `.filter(!is_empty)` must reject it and fall through to the fallback
+        // rather than returning "" (which would collapse callers into one bucket).
+        let mut h = HeaderMap::new();
+        h.insert("x-forwarded-for", "203.0.113.7, ".parse().unwrap());
+        assert_eq!(client_ip(&h, "127.0.0.1"), "127.0.0.1");
     }
 }

backend/src/services/sse_tickets.rs

@@ -13,6 +13,36 @@ use rand::Rng;
 /// stream open. Tickets are consumed on use and expire after `TTL`.
 const TTL: Duration = Duration::from_secs(30);
 
+/// Ceiling on outstanding tickets across the whole process.
+///
+/// Not really about the bytes (~120 each) — about `issue` having had no bound of any kind.
+/// Sized well above a real event: ~1000 concurrent clients each holding one live 30 s ticket.
+const MAX_TICKETS: usize = 4096;
+
+/// Live tickets one session may hold. Above 1 because two tabs sharing a token open their
+/// EventSources concurrently; 4 absorbs that without letting a reconnect loop accumulate.
+const MAX_TICKETS_PER_SESSION: usize = 4;
+
+/// What a ticket may be redeemed for.
+///
+/// The store began life serving only SSE and stayed untyped when the export download started
+/// reusing it, which silently made the two interchangeable. That is not a theoretical mixing
+/// concern: `POST /stream/ticket` is rate-limited at 60/min per user and charges nothing, while
+/// `POST /export/ticket` charges one of three PER-DAY downloads. An untyped ticket let any guest
+/// mint at the cheap endpoint and redeem at the expensive one, so the daily export limit was
+/// bypassable ~60×/minute — each redemption streaming the whole multi-GB keepsake, `no-store`,
+/// off the same filesystem Postgres writes WAL to.
+///
+/// `consume` therefore requires the kind to MATCH. A ticket is only ever valid for the thing it
+/// was minted for.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum TicketKind {
+    /// Opens the SSE stream (`GET /stream`). Cheap, high volume.
+    Sse,
+    /// Downloads an export archive (`GET /export/{zip,html}`). Expensive, rate-limited per day.
+    Download,
+}
+
 #[derive(Clone)]
 pub struct SseTicketStore {
     inner: Arc<Mutex<HashMap<String, Entry>>>,
@@ -22,6 +52,7 @@ pub struct SseTicketStore {
 struct Entry {
     token_hash: String,
     issued_at: Instant,
+    kind: TicketKind,
 }
 
 impl SseTicketStore {
@@ -31,29 +62,88 @@ impl SseTicketStore {
         }
     }
 
+    /// Drop every outstanding ticket. Used by the e2e TRUNCATE endpoint: tickets are bound to a
+    /// session token hash, and TRUNCATE deletes the sessions out from under them, so anything left
+    /// here is a dangling reference to a user that no longer exists.
+    pub fn clear(&self) {
+        self.inner.lock().unwrap().clear();
+    }
+
     /// Mint a new ticket bound to the caller's session (identified by token hash).
-    pub fn issue(&self, token_hash: String) -> String {
+    ///
+    /// `None` when the store is at capacity — the caller should answer 503, not evict.
+    ///
+    /// Three bounds, because `issue` had none: no size cap, no per-caller cap, and no rate
+    /// limit on the endpoint, while `prune` ran only hourly against a 30-second TTL. So any
+    /// authenticated session could loop the endpoint and grow the map for an hour.
+    pub fn issue(&self, token_hash: String, kind: TicketKind) -> Option<String> {
         let ticket = random_ticket();
         let mut map = self.inner.lock().unwrap();
+
+        // Prune on issue rather than only hourly. This alone changes the bound from "tickets
+        // minted since the last maintenance tick" to "tickets live at once", which is what the
+        // 30 s TTL was always meant to express.
+        map.retain(|_, e| e.issued_at.elapsed() <= TTL);
+
+        // Cap the caller's own outstanding tickets, evicting their oldest. NOT one-per-session:
+        // two tabs sharing a token open their EventSources concurrently, and having tab B
+        // invalidate tab A's unconsumed ticket looks exactly like a flaky SSE connection.
+        let mut mine: Vec<(String, Instant)> = map
+            .iter()
+            .filter(|(_, e)| e.token_hash == token_hash)
+            .map(|(k, e)| (k.clone(), e.issued_at))
+            .collect();
+        if mine.len() >= MAX_TICKETS_PER_SESSION {
+            mine.sort_by_key(|(_, issued)| *issued);
+            for (key, _) in mine.iter().take(mine.len() - MAX_TICKETS_PER_SESSION + 1) {
+                map.remove(key);
+            }
+        }
+
+        // At capacity, REFUSE — never evict a stranger's ticket. Evicting would let one
+        // misbehaving client deny SSE to the whole venue, which is worse than failing the
+        // request that hit the ceiling.
+        if map.len() >= MAX_TICKETS {
+            tracing::warn!(
+                outstanding = map.len(),
+                "SSE ticket store at capacity; refusing to mint"
+            );
+            return None;
+        }
+
         map.insert(
             ticket.clone(),
             Entry {
                 token_hash,
                 issued_at: Instant::now(),
+                kind,
             },
         );
-        ticket
+        Some(ticket)
     }
 
-    /// Consume a ticket. Returns `Some(token_hash)` if the ticket exists and is
-    /// not expired. Single-use: the ticket is removed regardless of whether it
-    /// was still fresh, so a replay can't slip through after expiry.
-    pub fn consume(&self, ticket: &str) -> Option<String> {
+    /// Consume a ticket minted for `kind`. Returns `Some(token_hash)` if the ticket exists, is
+    /// not expired, and was minted for this purpose. Single-use: the ticket is removed regardless
+    /// of whether it was still fresh, so a replay can't slip through after expiry.
+    ///
+    /// A ticket of the WRONG kind is also removed. It was a valid ticket the caller legitimately
+    /// held, so this is not punitive — but leaving it would let a redemption loop probe the store
+    /// without ever spending anything, and the client has no legitimate reason to present a
+    /// ticket at the wrong endpoint.
+    pub fn consume(&self, ticket: &str, kind: TicketKind) -> Option<String> {
         let mut map = self.inner.lock().unwrap();
         let entry = map.remove(ticket)?;
         if entry.issued_at.elapsed() > TTL {
             return None;
         }
+        if entry.kind != kind {
+            tracing::warn!(
+                expected = ?kind,
+                found = ?entry.kind,
+                "ticket presented at the wrong endpoint; rejected"
+            );
+            return None;
+        }
         Some(entry.token_hash)
     }
 
@@ -72,3 +162,186 @@ fn random_ticket() -> String {
     rng.fill(&mut bytes);
     bytes.iter().map(|b| format!("{b:02x}")).collect()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// `issue` now returns `Option`; in every test below the store is far from capacity, so an
+    /// `expect` here documents that refusing is exceptional rather than routine.
+    fn issue(store: &SseTicketStore, hash: &str) -> String {
+        store
+            .issue(hash.into(), TicketKind::Sse)
+            .expect("store has capacity")
+    }
+
+    /// The store is shared by two endpoints with wildly different costs: `/stream/ticket` is
+    /// 60/min per user and free, `/export/ticket` charges one of three PER-DAY downloads. While
+    /// entries were untyped, a ticket minted at the cheap endpoint opened the expensive one — so
+    /// the daily export limit could be bypassed ~60×/minute, each redemption streaming the whole
+    /// multi-GB keepsake off the disk Postgres writes WAL to.
+    ///
+    /// Asserted in BOTH directions so this cannot be "fixed" by a check that only guards one.
+    #[test]
+    fn a_ticket_is_only_valid_for_the_purpose_it_was_minted_for() {
+        let store = SseTicketStore::new();
+
+        let sse = store.issue("h".into(), TicketKind::Sse).unwrap();
+        assert_eq!(
+            store.consume(&sse, TicketKind::Download),
+            None,
+            "an SSE ticket must not open the export download"
+        );
+
+        let dl = store.issue("h".into(), TicketKind::Download).unwrap();
+        assert_eq!(
+            store.consume(&dl, TicketKind::Sse),
+            None,
+            "a download ticket must not open the SSE stream"
+        );
+
+        // And the matching cases still work, so the guard is not simply rejecting everything.
+        let sse = store.issue("h".into(), TicketKind::Sse).unwrap();
+        assert_eq!(store.consume(&sse, TicketKind::Sse).as_deref(), Some("h"));
+        let dl = store.issue("h".into(), TicketKind::Download).unwrap();
+        assert_eq!(
+            store.consume(&dl, TicketKind::Download).as_deref(),
+            Some("h")
+        );
+    }
+
+    #[test]
+    fn issue_then_consume_returns_the_hash_exactly_once() {
+        let store = SseTicketStore::new();
+        let ticket = issue(&store, "hash-1");
+        assert_eq!(store.consume(&ticket, TicketKind::Sse).as_deref(), Some("hash-1"));
+        // Single-use: a replay of the same ticket is rejected.
+        assert_eq!(
+            store.consume(&ticket, TicketKind::Sse),
+            None,
+            "a consumed ticket must not be reusable"
+        );
+    }
+
+    #[test]
+    fn unknown_ticket_consumes_to_none() {
+        let store = SseTicketStore::new();
+        assert_eq!(store.consume("never-issued", TicketKind::Sse), None);
+    }
+
+    #[test]
+    fn issued_tickets_are_unique_and_hex() {
+        let store = SseTicketStore::new();
+        let a = issue(&store, "h");
+        let b = issue(&store, "h");
+        assert_ne!(a, b, "each ticket must be unique");
+        assert_eq!(a.len(), 48, "24 random bytes → 48 hex chars");
+        assert!(a.chars().all(|c| c.is_ascii_hexdigit()));
+    }
+
+    #[test]
+    fn fresh_ticket_survives_prune() {
+        let store = SseTicketStore::new();
+        let ticket = issue(&store, "h");
+        store.prune(); // not expired → kept
+        assert_eq!(store.consume(&ticket, TicketKind::Sse).as_deref(), Some("h"));
+    }
+
+    /// Build an entry that is already past the TTL.
+    fn insert_stale(store: &SseTicketStore, key: &str, token_hash: &str) {
+        store.inner.lock().unwrap().insert(
+            key.to_string(),
+            Entry {
+                kind: TicketKind::Sse,
+                token_hash: token_hash.into(),
+                issued_at: Instant::now()
+                    .checked_sub(TTL + Duration::from_secs(1))
+                    .expect("host uptime should exceed the ticket TTL"),
+            },
+        );
+    }
+
+    #[test]
+    fn expired_ticket_consumes_to_none() {
+        let store = SseTicketStore::new();
+        insert_stale(&store, "stale-ticket", "h");
+        assert_eq!(
+            store.consume("stale-ticket", TicketKind::Sse),
+            None,
+            "an expired ticket must not authenticate"
+        );
+    }
+
+    /// The TTL is 30 s but `prune` only ran hourly, so the map was really bounded by "tickets
+    /// minted in the last hour" — which is unbounded for a client in a loop.
+    #[test]
+    fn issuing_prunes_expired_entries() {
+        let store = SseTicketStore::new();
+        insert_stale(&store, "stale-a", "someone-else");
+        insert_stale(&store, "stale-b", "someone-else");
+        issue(&store, "h");
+        assert_eq!(
+            store.inner.lock().unwrap().len(),
+            1,
+            "issue must reclaim expired slots, not merely add to them"
+        );
+    }
+
+    /// Two tabs sharing a token is normal, so the per-session cap must be above 1 — but a
+    /// reconnect loop must not accumulate. The caller's OWN oldest is what gets evicted.
+    #[test]
+    fn a_session_is_capped_and_evicts_only_its_own_oldest() {
+        let store = SseTicketStore::new();
+        let stranger = issue(&store, "other-session");
+
+        let mut mine: Vec<String> = Vec::new();
+        for _ in 0..MAX_TICKETS_PER_SESSION + 2 {
+            mine.push(issue(&store, "mine"));
+        }
+
+        let live = mine
+            .iter()
+            .filter(|t| store.inner.lock().unwrap().contains_key(*t))
+            .count();
+        assert_eq!(live, MAX_TICKETS_PER_SESSION, "one session, bounded");
+        assert!(
+            store.inner.lock().unwrap().contains_key(&mine[mine.len() - 1]),
+            "the newest ticket is the one the caller is about to use"
+        );
+        assert_eq!(
+            store.consume(&stranger, TicketKind::Sse).as_deref(),
+            Some("other-session"),
+            "another session's ticket must survive — evicting it would let one client deny \
+             SSE to the venue"
+        );
+    }
+
+    /// At capacity the store REFUSES rather than evicting a stranger. Refusing fails the one
+    /// request that hit the ceiling; evicting would break an unrelated client's live stream.
+    #[test]
+    fn at_capacity_the_store_refuses_instead_of_evicting() {
+        let store = SseTicketStore::new();
+        {
+            let mut map = store.inner.lock().unwrap();
+            for i in 0..MAX_TICKETS {
+                map.insert(
+                    format!("filler-{i}"),
+                    Entry {
+                        kind: TicketKind::Sse,
+                        token_hash: format!("session-{i}"),
+                        issued_at: Instant::now(),
+                    },
+                );
+            }
+        }
+        assert_eq!(
+            store.issue("newcomer".into(), TicketKind::Sse),
+            None,
+            "a full store must refuse, so the caller can answer 503"
+        );
+        assert!(
+            store.inner.lock().unwrap().contains_key("filler-0"),
+            "no existing ticket may be sacrificed to make room"
+        );
+    }
+}

backend/src/services/upload_admission.rs

@@ -0,0 +1,155 @@
+//! Admission control for upload bodies, budgeted in BYTES rather than requests.
+//!
+//! ## Why this has to exist
+//!
+//! The keepsake headroom gate in `handlers::upload` cannot bound a burst, and the reason is
+//! structural rather than a bug in the gate: the request body is streamed to a temp file during
+//! multipart parsing, so the bytes are already on disk by the time any check runs. The gate can
+//! only refuse to COMMIT them. Nothing upstream limited how many bodies stream at once — axum has
+//! no such limit, the tower stack is just `TraceLayer`, and Caddy passes requests straight
+//! through.
+//!
+//! So the failure mode is the ordinary one, not an attack: the ceremony ends, ~100 guests tap
+//! "upload all", and ~100 bodies stream concurrently. At phone-video sizes that is 10-20 GB of
+//! `.tmp` files on a 40 GB volume, none of it visible to the gate, and `DISK_RESERVE_BYTES` — the
+//! 10 GB standing between the party and Postgres losing the volume it writes WAL to — is consumed
+//! by transient files. The `.tmp` sweeper only reclaims files idle for an hour, correctly, which
+//! means nothing reclaims a burst on this timescale.
+//!
+//! ## Why bytes and not a request count
+//!
+//! A flat "N concurrent uploads" limit has to be sized for the worst case (a 500 MB video), which
+//! makes it absurdly restrictive for the common case (a 3 MB photo). Budgeting bytes lets one
+//! 500 MB video and two hundred photos coexist under the same ceiling, and it means the ceiling is
+//! stated in the unit the disk actually cares about.
+//!
+//! The reservation is the streaming CAP, not the real size — the real size is unknowable until the
+//! body has been read, which is far too late. Reserving the cap is deliberately pessimistic; that
+//! pessimism is the safety margin.
+//!
+//! ## Why a permit and not a counter
+//!
+//! `OwnedSemaphorePermit` releases on drop. Every path out of the upload handler — success, error,
+//! a client vanishing mid-body, a panic — therefore returns the reservation without any explicit
+//! bookkeeping. A hand-rolled `AtomicI64` would need a decrement on each of those paths, and the
+//! one that gets missed is the one that leaks the budget until restart.
+
+use std::sync::Arc;
+use std::time::Duration;
+
+use tokio::sync::{OwnedSemaphorePermit, Semaphore};
+
+/// Total transient upload bytes allowed on disk at once, in MiB.
+///
+/// Sized against `DISK_RESERVE_BYTES` (10 GB): the reserve must survive a full burst with room to
+/// spare, since Postgres is writing WAL to the same filesystem throughout. 4 GiB leaves ~6 GB of
+/// the reserve untouched at the worst moment.
+///
+/// It is NOT a throughput limit. On 2 vCPU the box cannot usefully ingest more than this at once
+/// anyway — compression, ffmpeg, Postgres and TLS all contend for the same two cores — so the
+/// budget mostly converts "everything is slow and the disk fills" into "a few uploads wait".
+const BUDGET_MIB: u32 = 4096;
+
+/// How long an upload waits for room before being told to come back.
+///
+/// Long enough to absorb the burst (a photo holds its reservation for well under a second), short
+/// enough that a guest is not left staring at a spinner. On timeout the handler answers 503 with
+/// `Retry-After`, which the client queue already treats as transient and retries with backoff.
+const WAIT: Duration = Duration::from_secs(20);
+
+#[derive(Clone)]
+pub struct UploadAdmission {
+    permits: Arc<Semaphore>,
+}
+
+impl UploadAdmission {
+    pub fn new() -> Self {
+        Self {
+            permits: Arc::new(Semaphore::new(BUDGET_MIB as usize)),
+        }
+    }
+
+    /// Reserve room for a body capped at `cap_bytes`. The returned permit must be held for as long
+    /// as the temp file exists.
+    ///
+    /// `None` means the wait timed out and the caller should shed the request.
+    ///
+    /// A cap larger than the whole budget is clamped rather than refused. Otherwise an operator
+    /// raising `max_video_size_mb` above the budget would make `acquire_many` unsatisfiable and
+    /// every video upload would hang until timeout — a config change silently disabling video for
+    /// the event. Clamped, such an upload simply gets the whole budget to itself, which is the
+    /// honest interpretation of "one file may fill the machine".
+    pub async fn reserve(&self, cap_bytes: usize) -> Option<OwnedSemaphorePermit> {
+        let mib = cap_bytes.div_ceil(1024 * 1024).max(1);
+        let want = u32::try_from(mib).unwrap_or(BUDGET_MIB).min(BUDGET_MIB);
+        match tokio::time::timeout(
+            WAIT,
+            self.permits.clone().acquire_many_owned(want),
+        )
+        .await
+        {
+            Ok(Ok(permit)) => Some(permit),
+            // The semaphore is never closed, so `Err` here is unreachable in practice; treat it
+            // the same as a timeout rather than panicking on the upload path.
+            Ok(Err(_)) => None,
+            Err(_) => {
+                tracing::warn!(
+                    requested_mib = want,
+                    "upload admission timed out; shedding to keep transient temp files bounded"
+                );
+                None
+            }
+        }
+    }
+}
+
+impl Default for UploadAdmission {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// The budget must actually block once exhausted — otherwise this whole module is decoration.
+    #[tokio::test]
+    async fn a_full_budget_sheds_instead_of_admitting() {
+        let admission = UploadAdmission::new();
+        let whole = admission
+            .reserve(BUDGET_MIB as usize * 1024 * 1024)
+            .await
+            .expect("first reservation takes the whole budget");
+
+        // Nothing left: a second reservation must not be granted. Raced against a short timeout so
+        // the test does not sit for the full WAIT.
+        let blocked = tokio::time::timeout(
+            Duration::from_millis(150),
+            admission.reserve(1024 * 1024),
+        )
+        .await;
+        assert!(blocked.is_err(), "budget exhausted, yet a reservation was granted");
+
+        // ...and releasing the permit makes room again, so the budget is not a one-way latch.
+        drop(whole);
+        assert!(
+            admission.reserve(1024 * 1024).await.is_some(),
+            "budget did not recover after the permit was dropped"
+        );
+    }
+
+    /// A cap above the whole budget must be clamped, not left unsatisfiable. Unclamped,
+    /// `acquire_many` for more permits than exist never completes, so raising
+    /// `max_video_size_mb` past the budget would silently hang every video upload for 20s and
+    /// then shed it.
+    #[tokio::test]
+    async fn a_cap_larger_than_the_budget_is_clamped_rather_than_unsatisfiable() {
+        let admission = UploadAdmission::new();
+        let oversized = (BUDGET_MIB as usize + 4096) * 1024 * 1024;
+        assert!(
+            admission.reserve(oversized).await.is_some(),
+            "an over-budget cap must still be admittable on an idle server"
+        );
+    }
+}

backend/src/services/video.rs

@@ -0,0 +1,263 @@
+//! Poster-frame extraction, shared by the compression worker and the HTML export.
+//!
+//! Both used to spawn `ffmpeg` themselves with the same broken invocation:
+//!
+//! ```text
+//! ffmpeg -i <src> -vframes 1 -ss 00:00:01 -vf scale=… -y <out>
+//! ```
+//!
+//! `-ss` AFTER `-i` is an output-side seek. Against a clip of a second or less ffmpeg exits **0 and
+//! writes nothing** — and both call sites gated on the exit status, so neither noticed. The worker
+//! then wrote `thumbnail_path` for a file that was never created (404 in the live feed) and the
+//! export listed the entry in `data.json` while the ZIP writer skipped it (a broken image tile in
+//! the keepsake). Every server-side signal stayed green. Phones produce such clips constantly:
+//! mis-taps, Live Photos, boomerangs.
+//!
+//! This module exists for the same reason `imaging.rs` does — that one was created when compression
+//! and export duplicated decode logic, and it paid off immediately when the `max_alloc` fix landed
+//! in both workers at once. Same duplication, same fix.
+
+use std::path::Path;
+use std::time::Duration;
+
+use anyhow::{Context, Result};
+
+/// A malformed video can hang `ffmpeg` indefinitely. In the compression worker that never releases
+/// the semaphore permit and the pool eventually deadlocks; in the export worker it strands the job
+/// at `running` so the keepsake never completes. `export.rs` had NO timeout at all before this
+/// module — sharing the spawn fixes that too.
+/// 45s, not the 120s this started at. The timeout is not a budget for honest work — a poster
+/// frame from a phone clip takes well under a second, and `-ss` before `-i` means even a 500 MB
+/// file seeks rather than scans. It is purely the ceiling on how long a pathological input may
+/// hold a compression permit that guests' photos are queued behind, so it should be as tight as
+/// it can be without ever cutting off real work.
+const FFMPEG_TIMEOUT: Duration = Duration::from_secs(45);
+
+/// Seek positions to try, in order.
+///
+/// One second first: the opening frame of a real video is often black, a fade-in, or motion-blurred
+/// as the camera settles, so it makes a poor poster. Zero second as the fallback, which is what
+/// makes short clips work — and it is genuinely required, not defensive. Moving `-ss` before `-i`
+/// (an input-side seek) is necessary but NOT sufficient: seeking to 1 s in a 1.000 s clip is still
+/// past the last frame, and ffmpeg still exits 0 having written nothing. Verified against the real
+/// production image.
+const SEEK_POSITIONS: &[&str] = &["00:00:01", "0"];
+
+/// Extract one poster frame from `src` into `dest`, scaled to `width` px wide.
+///
+/// `Ok(false)` means the video yielded no frame — a normal outcome for a very short or unusual
+/// clip, NOT an error. Callers must degrade (no poster) rather than fail the upload: treating this
+/// as an error would soft-delete every sub-second video, turning a cosmetic defect into data loss.
+///
+/// `Err` is reserved for something genuinely wrong — a hang we had to kill, or a failure to spawn.
+pub async fn extract_poster_frame(src: &Path, dest: &Path, width: u32) -> Result<bool> {
+    for seek in SEEK_POSITIONS {
+        // A stale file from a previous attempt would be indistinguishable from a fresh success.
+        let _ = tokio::fs::remove_file(dest).await;
+
+        run_ffmpeg(src, dest, width, seek).await?;
+
+        // THE CHECK BOTH CALL SITES WERE MISSING: ask the filesystem, not the exit status.
+        // Non-empty, because a zero-byte file is not a poster either.
+        if tokio::fs::metadata(dest)
+            .await
+            .map(|m| m.is_file() && m.len() > 0)
+            .unwrap_or(false)
+        {
+            return Ok(true);
+        }
+    }
+
+    // Leave nothing behind for a caller to mistake for a result.
+    let _ = tokio::fs::remove_file(dest).await;
+    Ok(false)
+}
+
+/// Run one ffmpeg attempt. A non-zero exit is NOT an error here — the artifact check above is the
+/// authority, and a corrupt input that fails at 1 s may still yield a frame at 0.
+async fn run_ffmpeg(src: &Path, dest: &Path, width: u32, seek: &str) -> Result<()> {
+    let child = tokio::process::Command::new("ffmpeg")
+        .args([
+            // BEFORE -i: an input-side seek. See SEEK_POSITIONS.
+            "-ss",
+            seek,
+            "-i",
+            src.to_str().unwrap_or_default(),
+            "-vframes",
+            "1",
+            "-vf",
+            &format!("scale={width}:-1"),
+            "-y",
+            dest.to_str().unwrap_or_default(),
+        ])
+        // ffmpeg writes the poster to `dest` itself; nothing here ever reads stdout, so
+        // giving it a pipe only created something that could fill.
+        .stdout(std::process::Stdio::null())
+        // stderr IS piped — it is the only diagnostic when a clip yields no frame — but it
+        // must be DRAINED, which is the whole point of `wait_with_output` below.
+        .stderr(std::process::Stdio::piped())
+        .kill_on_drop(true)
+        .spawn()
+        .context("failed to spawn ffmpeg")?;
+
+    // `wait_with_output`, NOT `wait`. ffmpeg is verbose on stderr (banner, stream info,
+    // per-frame progress) and `wait()` reads neither pipe — so once the ~64 KiB pipe buffer
+    // filled, ffmpeg blocked writing, `wait()` never returned, and the call burned the full
+    // timeout. That is not merely slow: the timeout is an `Err`, so after 2 seek positions x
+    // 3 compression attempts the caller soft-deletes a perfectly playable video for a
+    // poster-frame failure. `wait_with_output` polls the pipe and the exit status together.
+    //
+    // It also CONSUMES the child, so the explicit `child.kill()` that used to sit on the
+    // timeout arm cannot exist here — and is not needed: `kill_on_drop(true)` is set above,
+    // and dropping the future on timeout drops the child with it.
+    let out = match tokio::time::timeout(FFMPEG_TIMEOUT, child.wait_with_output()).await {
+        Ok(res) => res.context("ffmpeg wait failed")?,
+        Err(_) => anyhow::bail!("ffmpeg timed out after {}s", FFMPEG_TIMEOUT.as_secs()),
+    };
+
+    // A non-zero exit is not an error (see the doc comment) — the artifact check in
+    // `extract_poster_frame` is the authority. Log the tail so a systematically failing
+    // format is diagnosable without turning it into data loss.
+    if !out.status.success() {
+        tracing::debug!(
+            seek,
+            status = ?out.status,
+            stderr = %tail_lines(&out.stderr, 10),
+            "ffmpeg exited non-zero; the artifact check decides"
+        );
+    }
+    Ok(())
+}
+
+/// Last `n` lines of a child's stderr, lossily decoded.
+///
+/// Bounded on purpose: ffmpeg's stderr is unbounded, and the reason we now drain it is that
+/// unbounded output used to be a hazard. Emitting all of it into a log line — into container
+/// logs that are themselves size-capped — would just move the problem.
+fn tail_lines(bytes: &[u8], n: usize) -> String {
+    let text = String::from_utf8_lossy(bytes);
+    let lines: Vec<&str> = text.lines().filter(|l| !l.trim().is_empty()).collect();
+    lines[lines.len().saturating_sub(n)..].join(" | ")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Is there a usable `ffmpeg` on PATH?
+    ///
+    /// The poster-frame path shells out, and `extract_poster_frame` documents `Err` as meaning
+    /// "a hang or a SPAWN failure" — which is exactly what a missing binary produces. So on a
+    /// machine without ffmpeg the test below stops exercising the case it names (missing INPUT)
+    /// and instead reports a code defect that isn't there. The runtime image installs ffmpeg
+    /// (see backend/Dockerfile), so this only ever skips on a bare developer machine.
+    fn ffmpeg_available() -> bool {
+        std::process::Command::new("ffmpeg")
+            .arg("-version")
+            .stdout(std::process::Stdio::null())
+            .stderr(std::process::Stdio::null())
+            .status()
+            .is_ok()
+    }
+
+    /// The order is the whole fix. `-ss` must precede `-i`, and 0 must be tried after 1 s.
+    #[test]
+    fn the_fallback_seek_exists_and_comes_last() {
+        assert_eq!(
+            SEEK_POSITIONS,
+            &["00:00:01", "0"],
+            "1s first for a better poster, 0 as the fallback that makes short clips work"
+        );
+    }
+
+    /// A missing input yields no frame rather than an error: the caller must degrade to "no
+    /// poster", never fail the upload. `Err` is reserved for a hang or a spawn failure.
+    #[tokio::test]
+    async fn a_missing_source_yields_no_frame_rather_than_an_error() {
+        if !ffmpeg_available() {
+            eprintln!(
+                "SKIP a_missing_source_yields_no_frame_rather_than_an_error: no ffmpeg on PATH. \
+                 A missing binary is a spawn failure, which this function returns Err for by \
+                 design, so the missing-INPUT case cannot be exercised here. Install ffmpeg to \
+                 run it (the runtime image already has it)."
+            );
+            return;
+        }
+        let dir = std::env::temp_dir().join(format!("es-video-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        let dest = dir.join("out.jpg");
+
+        let got = extract_poster_frame(Path::new("/nonexistent/clip.mp4"), &dest, 400).await;
+
+        match got {
+            Ok(false) => {}
+            other => panic!("expected Ok(false) for a missing input, got {other:?}"),
+        }
+        assert!(
+            !dest.exists(),
+            "a failed extraction must leave nothing a caller could mistake for a poster"
+        );
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn the_stderr_tail_is_bounded_and_survives_invalid_utf8() {
+        let noisy: Vec<u8> = (0..500)
+            .map(|i| format!("line {i}\n"))
+            .collect::<String>()
+            .into_bytes();
+        let got = tail_lines(&noisy, 3);
+        assert_eq!(got, "line 497 | line 498 | line 499");
+
+        // ffmpeg emits filenames verbatim, so its stderr is not guaranteed to be UTF-8.
+        assert_eq!(tail_lines(&[b'o', b'k', 0xff], 5), "ok\u{fffd}");
+        assert_eq!(tail_lines(b"", 5), "");
+    }
+
+    /// A real extraction must finish in a small fraction of `FFMPEG_TIMEOUT`.
+    ///
+    /// Wall-clock is the ONLY observable of the bug this guards: piping stderr and then
+    /// calling `wait()` (which drains nothing) blocks ffmpeg on a full pipe buffer until the
+    /// timeout fires, and the timeout is an `Err`, so the upload is soft-deleted. The
+    /// assertion is deliberately on elapsed time, not on the exit status.
+    ///
+    /// Honest limitation: our fixture is quiet enough not to fill a 64 KiB pipe on its own,
+    /// so this catches a regression to `wait()` only in combination with a verbose input. It
+    /// is still worth pinning — a reverted drain plus any chatty clip is data loss.
+    #[tokio::test]
+    async fn a_real_clip_yields_a_poster_well_inside_the_timeout() {
+        if tokio::process::Command::new("ffmpeg")
+            .arg("-version")
+            .stdout(std::process::Stdio::null())
+            .stderr(std::process::Stdio::null())
+            .status()
+            .await
+            .is_err()
+        {
+            eprintln!("skipping: ffmpeg not on PATH");
+            return;
+        }
+        let src = Path::new("../e2e/fixtures/media/sample.mp4");
+        if !src.exists() {
+            eprintln!("skipping: {} missing", src.display());
+            return;
+        }
+
+        let dir = std::env::temp_dir().join(format!("es-video-ok-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        let dest = dir.join("poster.jpg");
+
+        let started = std::time::Instant::now();
+        let got = extract_poster_frame(src, &dest, 400).await;
+        let elapsed = started.elapsed();
+
+        assert!(matches!(got, Ok(true)), "expected a poster, got {got:?}");
+        assert!(dest.metadata().unwrap().len() > 0);
+        assert!(
+            elapsed < FFMPEG_TIMEOUT / 4,
+            "extraction took {elapsed:?}; a drained stderr finishes in well under \
+             {FFMPEG_TIMEOUT:?} — this is the pipe-deadlock regression guard"
+        );
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}

backend/src/state.rs

@@ -1,19 +1,14 @@
-use std::sync::Arc;
-
 use sqlx::PgPool;
-use tokio::sync::{broadcast, Semaphore};
+use tokio::sync::broadcast;
 
 use crate::config::AppConfig;
 use crate::services::compression::CompressionWorker;
+use crate::services::config::ConfigCache;
+use crate::services::disk::DiskCache;
+use crate::services::media_total::MediaTotalCache;
 use crate::services::rate_limiter::RateLimiter;
 use crate::services::sse_tickets::SseTicketStore;
-
-/// Max concurrent in-flight `/upload` requests. Each holds its whole file in
-/// memory while reading the multipart body, so this bounds aggregate upload RAM
-/// to ~N × the 550 MB body cap (≈2.2 GB here) — keeping headroom for Postgres +
-/// the app on an 8 GB box. The per-user rate limiter is a *count* limiter
-/// (10/hr), not a concurrency cap, so this is the actual OOM guard. Tunable.
-pub const UPLOAD_MAX_CONCURRENCY: usize = 4;
+use crate::services::upload_admission::UploadAdmission;
 
 #[derive(Clone, Debug)]
 pub struct SseEvent {
@@ -40,21 +35,33 @@ pub struct AppState {
     pub compression: CompressionWorker,
     pub rate_limiter: RateLimiter,
     pub sse_tickets: SseTicketStore,
-    /// Caps concurrent upload-body buffering (see UPLOAD_MAX_CONCURRENCY).
-    pub upload_limiter: Arc<Semaphore>,
+    /// In-memory cache in front of the `config` table. Reads go through here; the
+    /// admin PATCH handler and the test reseed invalidate it after committing.
+    pub config_cache: ConfigCache,
+    /// Cached total/free bytes for the media filesystem (quota + admin stats).
+    pub disk_cache: DiskCache,
+    /// Cached sum of all media bytes, for the upload gate's keepsake-headroom check.
+    pub media_total: MediaTotalCache,
+    /// Byte budget for upload bodies currently streaming to temp files. The headroom gate can
+    /// only refuse to COMMIT bytes that are already on disk; this is what bounds how many get
+    /// there at once.
+    pub upload_admission: UploadAdmission,
 }
 
 impl AppState {
     pub fn new(pool: PgPool, config: AppConfig) -> Self {
-        let (sse_tx, _) = broadcast::channel(256);
-        // Independent image (2) and video (2) permit pools — see CompressionWorker.
+        // Broadcast buffer for live SSE fan-out. Sized to absorb a burst (e.g. many
+        // uploads landing at once during a busy moment) before a slow consumer lags and
+        // has to `resync`. The resync path is a correctness backstop, not the happy path —
+        // a roomier buffer keeps ~1000 concurrent clients from all resyncing at once.
+        let (sse_tx, _) = broadcast::channel(1024);
         let compression = CompressionWorker::new(
             pool.clone(),
             config.media_path.clone(),
-            2,
-            2,
+            config.compression_concurrency,
             sse_tx.clone(),
         );
+        let config_cache = ConfigCache::new(pool.clone());
         Self {
             pool,
             config,
@@ -62,7 +69,10 @@ impl AppState {
             compression,
             rate_limiter: RateLimiter::new(),
             sse_tickets: SseTicketStore::new(),
-            upload_limiter: Arc::new(Semaphore::new(UPLOAD_MAX_CONCURRENCY)),
+            config_cache,
+            disk_cache: DiskCache::new(),
+            media_total: MediaTotalCache::new(),
+            upload_admission: UploadAdmission::new(),
         }
     }
 }

backend/static/export-viewer/_app/env.js

@@ -1 +0,0 @@
-export const env={}

backend/static/export-viewer/_app/immutable/chunks/BJ__EZ0W.js

@@ -1 +0,0 @@
-import{u as o,n as t,o as c}from"./CcONa1Mr.js";function u(e){throw new Error("https://svelte.dev/e/lifecycle_outside_component")}function r(e){t===null&&u(),o(()=>{const n=c(e);if(typeof n=="function")return n})}export{r as o};

backend/static/export-viewer/_app/immutable/chunks/BRDva_z9.js

@@ -1 +0,0 @@
-import{f as l,g as o,p as u,i as n,j as d,k as m,h as p,e as _,m as v,l as k}from"./CcONa1Mr.js";class w{anchor;#t=new Map;#s=new Map;#e=new Map;#i=new Set;#f=!0;constructor(t,s=!0){this.anchor=t,this.#f=s}#a=t=>{if(this.#t.has(t)){var s=this.#t.get(t),e=this.#s.get(s);if(e)l(e),this.#i.delete(s);else{var f=this.#e.get(s);f&&(this.#s.set(s,f.effect),this.#e.delete(s),f.fragment.lastChild.remove(),this.anchor.before(f.fragment),e=f.effect)}for(const[i,a]of this.#t){if(this.#t.delete(i),i===t)break;const r=this.#e.get(a);r&&(o(r.effect),this.#e.delete(a))}for(const[i,a]of this.#s){if(i===s||this.#i.has(i))continue;const r=()=>{if(Array.from(this.#t.values()).includes(i)){var c=document.createDocumentFragment();v(a,c),c.append(n()),this.#e.set(i,{effect:a,fragment:c})}else o(a);this.#i.delete(i),this.#s.delete(i)};this.#f||!e?(this.#i.add(i),u(a,r,!1)):r()}}};#r=t=>{this.#t.delete(t);const s=Array.from(this.#t.values());for(const[e,f]of this.#e)s.includes(e)||(o(f.effect),this.#e.delete(e))};ensure(t,s){var e=m,f=k();if(s&&!this.#s.has(t)&&!this.#e.has(t))if(f){var i=document.createDocumentFragment(),a=n();i.append(a),this.#e.set(t,{effect:d(()=>s(a)),fragment:i})}else this.#s.set(t,d(()=>s(this.anchor)));if(this.#t.set(e,t),f){for(const[r,h]of this.#s)r===t?e.unskip_effect(h):e.skip_effect(h);for(const[r,h]of this.#e)r===t?e.unskip_effect(h.effect):e.skip_effect(h.effect);e.oncommit(this.#a),e.ondiscard(this.#r)}else p&&(this.anchor=_),this.#a(e)}}export{w as B};

backend/static/export-viewer/_app/immutable/chunks/Bxn6SmGf.js

@@ -1 +0,0 @@
-import{b as c,h as o,a as l,E as b,r as p,s as v,c as g,d,e as m}from"./CcONa1Mr.js";import{B as y}from"./BRDva_z9.js";function k(f,h,_=!1){var n;o&&(n=m,l());var s=new y(f),u=_?b:0;function t(a,r){if(o){var e=p(n);if(a!==parseInt(e.substring(1))){var i=v();g(i),s.anchor=i,d(!1),s.ensure(a,r),d(!0);return}}s.ensure(a,r)}c(()=>{var a=!1;h((r,e=0)=>{a=!0,t(e,r)}),a||t(-1,null)},u)}export{k as i};

backend/static/export-viewer/_app/immutable/chunks/RsTAN2PN.js

@@ -1 +0,0 @@
-import{A as v,i as d,B as l,C as u,D as T,T as p,F as h,h as i,e as s,R as E,a as y,G as g,c as w,H as N}from"./CcONa1Mr.js";const A=globalThis?.window?.trustedTypes&&globalThis.window.trustedTypes.createPolicy("svelte-trusted-html",{createHTML:t=>t});function M(t){return A?.createHTML(t)??t}function x(t){var r=v("template");return r.innerHTML=M(t.replaceAll("<!>","<!---->")),r.content}function n(t,r){var e=l;e.nodes===null&&(e.nodes={start:t,end:r,a:null,t:null})}function b(t,r){var e=(r&p)!==0,f=(r&h)!==0,a,_=!t.startsWith("<!>");return()=>{if(i)return n(s,null),s;a===void 0&&(a=x(_?t:"<!>"+t),e||(a=u(a)));var o=f||T?document.importNode(a,!0):a.cloneNode(!0);if(e){var c=u(o),m=o.lastChild;n(c,m)}else n(o,o);return o}}function C(t=""){if(!i){var r=d(t+"");return n(r,r),r}var e=s;return e.nodeType!==g?(e.before(e=d()),w(e)):N(e),n(e,e),e}function O(){if(i)return n(s,null),s;var t=document.createDocumentFragment(),r=document.createComment(""),e=d();return t.append(r,e),n(r,e),t}function P(t,r){if(i){var e=l;((e.f&E)===0||e.nodes.end===null)&&(e.nodes.end=s),y();return}t!==null&&t.before(r)}const L="5";typeof window<"u"&&((window.__svelte??={}).v??=new Set).add(L);export{P as a,n as b,O as c,b as f,C as t};