chore: raise the db memory limit and rate-limit social writes

Two smaller operational items.

POSTGRES 512M -> 1G. DATABASE_MAX_CONNECTIONS is 30 for a ~100-guest event (feed
polling + SSE + uploads at once), and 30 backends plus Postgres 16's default
shared_buffers leaves very little headroom at 512M. An OOM here doesn't degrade one
feature -- every request path touches the database, so it takes the event down.
Memory is the cheaper knob than shrinking the pool back and reintroducing the
queueing it was raised to fix. .env.example now names the pairing explicitly, the way
it already does for COMPRESSION_WORKER_CONCURRENCY.

SOCIAL WRITES WERE UNTHROTTLED. toggle_like, add_comment and delete_comment were the
only mutating endpoints in the app with no limit at all -- upload, join, recover,
export and admin login all carry one. Asymmetric coverage rather than a deliberate
decision.

Low severity, and honestly so: a like fans an SSE broadcast to every client, but the
export regeneration a comment deletion triggers is contained (REGEN_DEBOUNCE 20s,
workers born with their epoch, superseded ones inert). So the ceiling is 120/min --
far above anything a real guest produces. This bounds a script, not an enthusiastic
double-tapper.

ONE bucket across all three actions: separate buckets would let a caller triple the
aggregate write rate by alternating between them. Keyed per USER, matching the feed
and upload limits -- at a venue every guest is behind one NAT, and an IP key is what
made the /join and /feed limits turn guests away in the first place.

Migration 020 seeds both keys, and both are wired into the admin allowlist, the
config UI and the e2e reseed -- the step two earlier per-area toggles missed, which
left switches that existed in code and could never be flipped.

Tests: 4 e2e, including that the shared bucket really is shared (the part most likely
to be lost in a refactor) and that one guest hitting the ceiling doesn't block
another behind the same IP.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.env.example

@@ -18,6 +18,10 @@ POSTGRES_PASSWORD=CHANGE_ME_use_a_strong_password
 POSTGRES_DB=eventsnap
 # Connection pool size. Default 10. For a busy event (~100 guests polling the feed
 # + SSE + uploads at once) raise to ~30 so requests don't queue on a pool permit.
+# PAIRED WITH THE DB CONTAINER'S MEMORY LIMIT: 30 backends plus Postgres 16's default
+# shared_buffers is already snug in the 1G that docker-compose.yml allots the `db`
+# service. If you raise this, raise `db.deploy.resources.limits.memory` with it — an
+# OOM in Postgres doesn't degrade one feature, it takes the whole event down.
 DATABASE_MAX_CONNECTIONS=30
 
 # ── Authentication ────────────────────────────────────────────────────────────
@@ -54,8 +58,26 @@ EXPORT_PATH=/exports
 #   max image size    20 MB
 #   max video size   500 MB
 #   estimated guests 100
-#   quota tolerance  0.75  (fraction of disk that triggers the low-storage warning)
+#   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 image/video compression workers. Default 2. This is the main

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
@@ -231,6 +230,45 @@ 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.
+
+Uploads are self-limiting. `per_user_limit = free_disk × quota_tolerance ÷
+active_uploaders` is recomputed against live free space on every upload, so guests
+converge on a fixed point at `tolerance / (1 + tolerance)` of the free space you
+started with — **43%** at the default 0.75. On an 80 GB box with ~70 GB free after
+the OS and images, media settles at ~30 GB and stops.
+
+**The keepsake is what the 80 GB baseline does not cover.** `Gallery.zip` and
+`Memories.zip` are built concurrently and each is 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.
+
+| Stage | Used | Free (80 GB box) |
+|---|---|---|
+| Fresh box (OS + images) | ~10 GB | ~70 GB |
+| Guests reach the quota fixed point | ~40 GB | ~40 GB |
+| Host releases → both archives | ~100 GB | **ENOSPC** |
+
+Two ways to size for it:
+
+- **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.
+
+This is no longer silent. The export refuses up front with the two numbers rather than
+hitting ENOSPC halfway through a multi-GB write, a rebuild reclaims the superseded
+generation before it starts (so peak is one generation, not two), 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
 
 There are **three** things to back up, and they live in three different places.
@@ -242,9 +280,12 @@ never exported into an operator's shell — so every command below runs through
 ```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 -U "$POSTGRES_USER" "$POSTGRES_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.
@@ -261,7 +302,7 @@ 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 .
 
-# Weekly offsite sync of the three artefacts above.
+# Offsite sync of the three artefacts above.
 rsync -az ./backups/ user@storagebox.example.com:backup/eventsnap/
 ```
 
@@ -274,6 +315,82 @@ from a directory called `eventsnap`. Confirm yours with `docker volume ls`.
 > 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
@@ -348,7 +465,7 @@ 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/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/src/handlers/admin.rs

@@ -127,6 +127,9 @@ pub async fn patch_config(
         // 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),
     ];
@@ -141,6 +144,7 @@ pub async fn patch_config(
         // 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",
         "quota_enabled",
         "storage_quota_enabled",
         "upload_count_quota_enabled",

backend/src/handlers/host.rs

@@ -35,6 +35,32 @@ 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,
+}
+
+/// Absolute floor below which free space is worth surfacing regardless of gallery size — the
+/// threshold the README has carried on the roadmap since v1.
+const LOW_DISK_FLOOR_BYTES: u64 = 10_000_000_000;
+
+/// 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.
+fn disk_is_low(free: u64, keepsake_required: u64) -> bool {
+    free < LOW_DISK_FLOOR_BYTES || free < keepsake_required
 }
 
 /// Count non-banned hosts/admins in the event OTHER than `excluding` — the operators
@@ -72,11 +98,29 @@ 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)),
     }))
 }
 
@@ -765,3 +809,45 @@ pub async fn release_gallery(
 
     Ok(StatusCode::NO_CONTENT)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{LOW_DISK_FLOOR_BYTES, disk_is_low};
+
+    const GB: u64 = 1_000_000_000;
+
+    #[test]
+    fn a_healthy_disk_with_room_for_the_keepsake_is_not_low() {
+        assert!(!disk_is_low(40 * GB, 25 * GB));
+    }
+
+    #[test]
+    fn the_absolute_floor_fires_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(LOW_DISK_FLOOR_BYTES - 1, 0));
+        assert!(!disk_is_low(LOW_DISK_FLOOR_BYTES, 0));
+    }
+
+    #[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() {
+        assert!(!disk_is_low(66 * GB, 66 * GB), "exactly enough is enough");
+        assert!(disk_is_low(66 * GB - 1, 66 * GB));
+    }
+
+    #[test]
+    fn an_empty_gallery_needs_nothing_and_only_the_floor_applies() {
+        assert!(!disk_is_low(11 * GB, 0));
+        assert!(disk_is_low(9 * GB, 0));
+    }
+}

backend/src/handlers/social.rs

@@ -10,8 +10,40 @@ 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
@@ -35,6 +67,7 @@ pub async fn toggle_like(
     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.
@@ -141,6 +174,7 @@ pub async fn add_comment(
     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)
@@ -216,6 +250,7 @@ pub async fn delete_comment(
     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()))?;

backend/src/handlers/test_admin.rs

@@ -63,6 +63,7 @@ pub async fn truncate_all(
             ('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'),
@@ -71,6 +72,7 @@ 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'),

backend/src/services/export.rs

@@ -1268,7 +1268,7 @@ fn is_superseded_archive(
 /// want, since being wrong low means ENOSPC halfway through.
 ///
 /// Matches [`query_uploads`]' visibility filter exactly, so hidden/banned uploads aren't counted.
-async fn estimate_export_bytes(pool: &PgPool, event_id: Uuid) -> Result<u64> {
+pub async fn estimate_export_bytes(pool: &PgPool, event_id: Uuid) -> Result<u64> {
     let (bytes,): (i64,) = sqlx::query_as(
         "SELECT COALESCE(SUM(u.original_size_bytes), 0)::bigint
            FROM upload u
@@ -1302,6 +1302,20 @@ fn required_free_bytes(media_bytes: u64, armed: i64) -> u64 {
     needed.min(u64::MAX as u128) as u64
 }
 
+/// Free bytes a full keepsake build would need RIGHT NOW, both halves included.
+///
+/// The same arithmetic the preflight uses, exposed so the host dashboard can warn BEFORE the
+/// release rather than reporting a failure after it. The preflight can only ever say "this didn't
+/// fit"; at that point the gallery is full, the event is over, and the remedies (ask guests to stop
+/// uploading, grow the volume) are all much harder. Hard-codes both halves because that is what a
+/// release arms.
+pub async fn keepsake_space_required(pool: &PgPool, event_id: Uuid) -> Result<u64> {
+    Ok(required_free_bytes(
+        estimate_export_bytes(pool, event_id).await?,
+        2,
+    ))
+}
+
 /// Refuse to start an export that cannot fit, with a reason the host can act on.
 ///
 /// Without this the failure mode is ENOSPC halfway through a multi-GB write, and the wreckage

backend/src/services/maintenance.rs

@@ -11,8 +11,9 @@
 //! 2. **Periodic tasks** — pruning that should happen "every hour" rather than per
 //!    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), and the originals of uploads whose compression permanently failed
-//!    (which are deliberately retained for a recovery window, then reclaimed).
+//!    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;
@@ -37,6 +38,27 @@ use crate::services::sse_tickets::SseTicketStore;
 /// 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.
@@ -117,38 +139,59 @@ pub fn spawn_periodic_tasks(
         loop {
             tick.tick().await;
             cleanup_sessions(&pool).await;
-            cleanup_failed_originals(&pool, &media_path).await;
+            cleanup_deleted_media(&pool, &media_path).await;
             rate_limiter.prune();
             sse_tickets.prune();
         }
     });
 }
 
-/// Reclaim the originals of uploads whose compression permanently failed, once they are
-/// past [`FAILED_ORIGINAL_RETENTION_DAYS`].
+/// Reclaim the media of soft-deleted uploads once they are past their retention window.
 ///
-/// Deliberately narrow. It only touches rows that are BOTH `compression_status = 'failed'`
-/// AND soft-deleted — i.e. the exact state the compression worker's give-up path leaves
-/// behind — so it can never reach a live upload or one whose preview works. `original_path`
-/// is cleared in the same pass, which makes the sweep idempotent and stops a later run
-/// re-reporting a file that is already gone. The row itself is kept: it is the audit trail
-/// for the failure, and it costs a few hundred bytes.
-async fn cleanup_failed_originals(pool: &PgPool, media_path: &std::path::Path) {
-    let rows = sqlx::query_as::<_, (uuid::Uuid, String)>(
-        "SELECT id, original_path FROM upload
-         WHERE compression_status = 'failed'
-           AND deleted_at IS NOT NULL
-           AND deleted_at < NOW() - ($1 || ' days')::interval
-           AND original_path <> ''",
+/// 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, "failed-original sweep query failed");
+            tracing::warn!(error = ?e, "deleted-media sweep query failed");
             return;
         }
     };
@@ -157,32 +200,52 @@ async fn cleanup_failed_originals(pool: &PgPool, media_path: &std::path::Path) {
     }
 
     let mut reclaimed = 0usize;
-    for (id, original_path) in rows {
-        let absolute = media_path.join(&original_path);
+    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 clear the column so
-            // the row stops being re-selected every hour.
+                // 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 failed original; leaving the row for the next sweep");
+                        "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 = '' WHERE id = $1")
+
+        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 file but could not clear original_path");
+            tracing::warn!(error = ?e, %id, "reclaimed the files but could not clear the paths");
         }
     }
 
     if reclaimed > 0 {
         tracing::info!(
-            "reclaimed {reclaimed} original(s) from uploads that failed compression more than \
-             {FAILED_ORIGINAL_RETENTION_DAYS} days ago"
+            "reclaimed {reclaimed} file(s) from soft-deleted uploads (deliberate deletes after \
+             {DELETED_UPLOAD_RETENTION_HOURS}h, compression failures after \
+             {FAILED_ORIGINAL_RETENTION_DAYS}d)"
         );
     }
 }

backend/tests/failed_original_sweep.rs

@@ -1,19 +1,27 @@
-//! DB-backed tests for the failed-original sweep (`services/maintenance.rs`).
+//! DB-backed tests for the deleted-media sweep (`services/maintenance.rs`).
 //!
-//! Context: the compression worker deliberately no longer deletes an upload's original when
-//! its transcode fails — a transient ENOSPC or a codec panic must never destroy the only
-//! copy of a photo a guest cannot retake. But the row is soft-deleted and the uploader's
-//! quota IS refunded, so those bytes become invisible, unowned and free. A guest hitting a
-//! reproducible codec failure could accumulate orphans at no personal cost, and since
-//! `active_uploaders` counts only users with non-deleted uploads, dropping out of that count
-//! actually RAISES everyone's per-user ceiling while the disk fills.
+//! Context, in two halves.
 //!
-//! The sweep reclaims them after a retention window. Its selection predicate is the whole
-//! safety argument — it must reach the give-up path's leftovers and nothing else — so that
-//! is what these tests pin, following the same "reproduce the SQL verbatim" pattern as
-//! `upload_concurrency.rs`.
+//! The compression worker deliberately no longer deletes an upload's original when its transcode
+//! fails — a transient ENOSPC or a codec panic must never destroy the only copy of a photo a guest
+//! cannot retake. But the row is soft-deleted and the uploader's quota IS refunded, so those bytes
+//! become invisible, unowned and free.
 //!
-//! `#[sqlx::test]` gives each test a fresh database with the real migrations applied.
+//! The SAME hole was reachable by the ordinary path, and that one is not an edge case at all:
+//! `soft_delete_in_event` refunds `total_upload_bytes` on every guest or host delete and nothing
+//! removed the files, so the quota stopped bounding the disk. Upload 500 MB, delete, quota back to
+//! zero, upload another 500 MB — a guest curating their camera roll, which is what people do. The
+//! sweep used to reach only `compression_status = 'failed'`, so it never touched this case; the
+//! test below that now asserts an owner-deleted upload IS reclaimed is the one that used to assert
+//! the opposite.
+//!
+//! Two windows, because the two deletes mean different things: 14 days for a failure an operator
+//! may want to investigate, 24 hours for a removal someone asked for (14 days outlives the whole
+//! event, so a deliberate delete would never reclaim anything while it mattered).
+//!
+//! The selection predicate is the whole safety argument — it must reach both leftovers and never a
+//! live upload — so that is what these pin, following the same "reproduce the SQL verbatim" pattern
+//! as `upload_concurrency.rs`. `#[sqlx::test]` gives each test a fresh, migrated database.
 
 mod common;
 
@@ -21,195 +29,324 @@ use common::*;
 use sqlx::PgPool;
 use uuid::Uuid;
 
-/// SRC: `services/maintenance.rs::cleanup_failed_originals` — the selection, verbatim.
-async fn sweep_selects(pool: &PgPool, retention_days: i64) -> Vec<Uuid> {
-    sqlx::query_as::<_, (Uuid, String)>(
-        "SELECT id, original_path FROM upload
-         WHERE compression_status = 'failed'
-           AND deleted_at IS NOT NULL
-           AND deleted_at < NOW() - ($1 || ' days')::interval
-           AND original_path <> ''",
+const FAILED_DAYS: i64 = 14;
+const DELETED_HOURS: i64 = 24;
+
+/// SRC: `services/maintenance.rs::cleanup_deleted_media` — the selection, verbatim.
+async fn sweep_selects(pool: &PgPool, failed_days: i64, deleted_hours: i64) -> Vec<Uuid> {
+    type Row = (Uuid, String, Option<String>, Option<String>, Option<String>);
+    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(retention_days.to_string())
+    .bind(failed_days.to_string())
+    .bind(deleted_hours.to_string())
     .fetch_all(pool)
     .await
     .expect("sweep query")
     .into_iter()
-    .map(|(id, _)| id)
+    .map(|(id, ..)| id)
     .collect()
 }
 
-#[allow(clippy::too_many_arguments)]
-async fn seed_upload(
+/// Seed an upload aged `deleted_hours_ago` (None = live), with optional derivative paths.
+async fn seed_aged_upload(
     pool: &PgPool,
     event_id: Uuid,
     user_id: Uuid,
     status: &str,
-    deleted_days_ago: Option<i64>,
+    deleted_hours_ago: Option<i64>,
     original_path: &str,
+    derivatives: bool,
 ) -> Uuid {
-    let id: Uuid = sqlx::query_scalar(
+    sqlx::query_scalar(
         "INSERT INTO upload (event_id, user_id, original_path, mime_type, original_size_bytes,
-                             compression_status, deleted_at)
+                             compression_status, deleted_at,
+                             preview_path, display_path, thumbnail_path)
          VALUES ($1, $2, $3, 'image/jpeg', 1000, $4,
                  CASE WHEN $5::bigint IS NULL THEN NULL
-                      ELSE NOW() - ($5::text || ' days')::interval END)
+                      ELSE NOW() - ($5::text || ' hours')::interval END,
+                 CASE WHEN $6 THEN 'previews/p.jpg' END,
+                 CASE WHEN $6 THEN 'displays/d.jpg' END,
+                 CASE WHEN $6 THEN 'thumbs/t.jpg' END)
          RETURNING id",
     )
     .bind(event_id)
     .bind(user_id)
     .bind(original_path)
     .bind(status)
-    .bind(deleted_days_ago)
+    .bind(deleted_hours_ago)
+    .bind(derivatives)
     .fetch_one(pool)
     .await
-    .expect("seed upload");
-    id
+    .expect("seed upload")
 }
 
+/// A live upload is untouchable no matter how the windows are configured.
+///
+/// PREVENTS: the catastrophic loosening. Everything else here is about reclaiming more; this is the
+/// one assertion that must never bend.
 #[sqlx::test]
-async fn sweeps_only_long_failed_soft_deleted_uploads(pool: PgPool) {
-    let event_id = seed_event(&pool, "sweep-event").await;
+async fn a_live_upload_is_never_selected(pool: PgPool) {
+    let event_id = seed_event(&pool, "sweep-live").await;
     let user_id = seed_user(&pool, event_id, "Sweeper").await;
 
-    // The one and only thing the sweep may touch: the exact state the compression worker's
-    // give-up path leaves behind, aged past the window.
-    let target = seed_upload(
+    for status in ["done", "failed", "processing", "pending"] {
+        let live = seed_aged_upload(
             &pool,
             event_id,
             user_id,
-        "failed",
-        Some(30),
-        "originals/e/target.jpg",
-    )
-    .await;
-
-    // Everything below is a near-miss that must survive.
-    // A healthy live upload — the catastrophic case if the predicate were ever loosened.
-    let live = seed_upload(
-        &pool,
-        event_id,
-        user_id,
-        "done",
+            status,
             None,
             "originals/e/live.jpg",
+            true,
         )
         .await;
-    // Failed but still inside the retention window: the recovery window is the entire point
-    // of keeping the file, so reclaiming it early would defeat the fix it protects.
-    let recent = seed_upload(
-        &pool,
-        event_id,
-        user_id,
-        "failed",
-        Some(1),
-        "originals/e/recent.jpg",
-    )
-    .await;
-    // Failed but NOT soft-deleted — not the give-up path; something else set this status.
-    let failed_live = seed_upload(
-        &pool,
-        event_id,
-        user_id,
-        "failed",
-        None,
-        "originals/e/failed-live.jpg",
-    )
-    .await;
-    // Soft-deleted by the OWNER, compression fine. Its file is already gone; this row must
-    // never be re-processed.
-    let owner_deleted = seed_upload(
+        assert!(
+            !sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS)
+                .await
+                .contains(&live),
+            "a non-deleted upload with status {status} must never be swept"
+        );
+    }
+}
+
+/// THE FIX. An upload a guest or host deliberately deleted is reclaimed once past 24 hours.
+///
+/// PREVENTS: the regression back to a sweep scoped to `compression_status = 'failed'`, which is
+/// what let the quota stop bounding the disk. This assertion is the inverse of the one this file
+/// used to make.
+#[sqlx::test]
+async fn a_deliberately_deleted_upload_is_reclaimed_after_a_day(pool: PgPool) {
+    let event_id = seed_event(&pool, "sweep-deleted").await;
+    let user_id = seed_user(&pool, event_id, "Curator").await;
+
+    let deleted = seed_aged_upload(
         &pool,
         event_id,
         user_id,
         "done",
-        Some(30),
+        Some(48),
         "originals/e/owner.jpg",
+        true,
+    )
+    .await;
+    // Still inside the window — a mis-tap is recoverable for a day.
+    let recent = seed_aged_upload(
+        &pool,
+        event_id,
+        user_id,
+        "done",
+        Some(2),
+        "originals/e/recent.jpg",
+        true,
     )
     .await;
-    // Already swept: `original_path` cleared. Re-selecting it every hour would log a
-    // phantom reclaim forever.
-    let already_swept = seed_upload(&pool, event_id, user_id, "failed", Some(30), "").await;
 
-    let selected = sweep_selects(&pool, 14).await;
-
-    assert_eq!(
-        selected,
-        vec![target],
-        "the sweep must select exactly the aged give-up-path leftovers"
+    let selected = sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS).await;
+    assert!(
+        selected.contains(&deleted),
+        "a deliberate delete past the window must be reclaimed — this is the leak"
+    );
+    assert!(
+        !selected.contains(&recent),
+        "a delete inside the window keeps its recovery grace"
     );
-    for (id, what) in [
-        (live, "a live upload"),
-        (recent, "a failure still inside the retention window"),
-        (failed_live, "a failed but not soft-deleted upload"),
-        (owner_deleted, "an owner-deleted upload"),
-        (already_swept, "an already-swept row"),
-    ] {
-        assert!(!selected.contains(&id), "the sweep must not touch {what}");
-    }
 }
 
+/// The two windows are independent: a failure is retained far longer than a deliberate delete.
+///
+/// PREVENTS: collapsing them into one. Applying 24h to failures would destroy the recovery window
+/// the retained-original fix exists to provide; applying 14 days to deliberate deletes would mean
+/// nothing is ever reclaimed during an event.
 #[sqlx::test]
-async fn retention_window_is_honoured_at_the_boundary(pool: PgPool) {
+async fn the_two_retention_windows_do_not_bleed_into_each_other(pool: PgPool) {
+    let event_id = seed_event(&pool, "sweep-windows").await;
+    let user_id = seed_user(&pool, event_id, "Windows").await;
+
+    // 48h old: past the deliberate window, nowhere near the failure window.
+    let failed_recent = seed_aged_upload(
+        &pool,
+        event_id,
+        user_id,
+        "failed",
+        Some(48),
+        "originals/e/f-recent.jpg",
+        false,
+    )
+    .await;
+    let deleted_same_age = seed_aged_upload(
+        &pool,
+        event_id,
+        user_id,
+        "done",
+        Some(48),
+        "originals/e/d-same.jpg",
+        false,
+    )
+    .await;
+    // 30 days old: past both.
+    let failed_old = seed_aged_upload(
+        &pool,
+        event_id,
+        user_id,
+        "failed",
+        Some(30 * 24),
+        "originals/e/f-old.jpg",
+        false,
+    )
+    .await;
+
+    let selected = sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS).await;
+    assert!(
+        !selected.contains(&failed_recent),
+        "a 2-day-old compression failure is still inside its 14-day recovery window"
+    );
+    assert!(
+        selected.contains(&deleted_same_age),
+        "a deliberate delete of the same age is past its 24-hour window"
+    );
+    assert!(
+        selected.contains(&failed_old),
+        "a 30-day-old failure is past both windows"
+    );
+}
+
+/// Boundary behaviour on both windows.
+#[sqlx::test]
+async fn retention_windows_are_honoured_at_the_boundary(pool: PgPool) {
     let event_id = seed_event(&pool, "sweep-boundary").await;
     let user_id = seed_user(&pool, event_id, "Boundary").await;
 
-    let inside = seed_upload(
+    let cases = [
+        ("failed", 13 * 24, false, "13 days"),
+        ("failed", 15 * 24, true, "15 days"),
+        ("done", 23, false, "23 hours"),
+        ("done", 25, true, "25 hours"),
+    ];
+    for (status, hours, expected, label) in cases {
+        let id = seed_aged_upload(
             &pool,
             event_id,
             user_id,
-        "failed",
-        Some(13),
-        "originals/e/inside.jpg",
+            status,
+            Some(hours),
+            "originals/e/b.jpg",
+            false,
         )
         .await;
-    let outside = seed_upload(
-        &pool,
-        event_id,
-        user_id,
-        "failed",
-        Some(15),
-        "originals/e/outside.jpg",
-    )
-    .await;
-
-    let selected = sweep_selects(&pool, 14).await;
-    assert!(
-        selected.contains(&outside),
-        "15 days old must be past a 14-day window"
-    );
-    assert!(
-        !selected.contains(&inside),
-        "13 days old must still be retained"
+        assert_eq!(
+            sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS)
+                .await
+                .contains(&id),
+            expected,
+            "a {status} upload deleted {label} ago: expected swept={expected}"
         );
+        sqlx::query("DELETE FROM upload WHERE id = $1")
+            .bind(id)
+            .execute(&pool)
+            .await
+            .expect("clean up");
+    }
 }
 
+/// A row is re-selected until EVERY one of its paths is cleared.
+///
+/// PREVENTS: two failures at once. The sweep used to clear `original_path` alone, which was right
+/// for its only case (a failed compression produces no derivatives) but leaves preview, display and
+/// thumbnail on disk the moment it reaches a successfully processed upload — three files per
+/// upload, none of them counted in `original_size_bytes`, that nothing else ever removes. And a row
+/// whose paths are all cleared must stop coming back, or every hourly tick logs a phantom reclaim
+/// forever.
 #[sqlx::test]
-async fn clearing_original_path_makes_the_sweep_idempotent(pool: PgPool) {
-    // The sweep clears `original_path` after reclaiming the file. Without that, a row whose
-    // file is already gone is re-selected on every hourly tick forever.
+async fn a_row_is_reselected_until_every_path_is_cleared(pool: PgPool) {
     let event_id = seed_event(&pool, "sweep-idempotent").await;
     let user_id = seed_user(&pool, event_id, "Idem").await;
-    let id = seed_upload(
+    let id = seed_aged_upload(
         &pool,
         event_id,
         user_id,
-        "failed",
-        Some(30),
+        "done",
+        Some(48),
         "originals/e/once.jpg",
+        true,
     )
     .await;
 
-    assert_eq!(sweep_selects(&pool, 14).await, vec![id]);
+    assert_eq!(sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS).await, [id]);
 
+    // Clearing only the original is NOT enough — the derivatives are still on disk.
     sqlx::query("UPDATE upload SET original_path = '' WHERE id = $1")
         .bind(id)
         .execute(&pool)
         .await
-        .expect("clear path");
+        .expect("clear original");
+    assert_eq!(
+        sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS).await,
+        [id],
+        "derivatives left behind must keep the row selected"
+    );
 
+    sqlx::query(
+        "UPDATE upload SET preview_path = NULL, display_path = NULL, thumbnail_path = NULL
+         WHERE id = $1",
+    )
+    .bind(id)
+    .execute(&pool)
+    .await
+    .expect("clear derivatives");
     assert!(
-        sweep_selects(&pool, 14).await.is_empty(),
-        "a swept row must not come back"
+        sweep_selects(&pool, FAILED_DAYS, DELETED_HOURS)
+            .await
+            .is_empty(),
+        "a fully swept row must not come back"
+    );
+}
+
+/// The derivative backfill must never resurrect what the sweep just reclaimed.
+///
+/// PREVENTS: an interaction, not a bug in either piece. The sweep nulls `preview_path`, and
+/// `backfill_stale_derivatives` selects on `display_path IS NULL AND preview_path IS NOT NULL` —
+/// close enough that a future edit to either could have the backfill re-decode an original that is
+/// no longer on disk, on every boot. `deleted_at IS NULL` is what keeps them apart.
+#[sqlx::test]
+async fn the_backfill_ignores_swept_rows(pool: PgPool) {
+    let event_id = seed_event(&pool, "sweep-backfill").await;
+    let user_id = seed_user(&pool, event_id, "Backfill").await;
+    seed_aged_upload(
+        &pool,
+        event_id,
+        user_id,
+        "done",
+        Some(48),
+        "originals/e/gone.jpg",
+        true,
+    )
+    .await;
+
+    // SRC: `services/compression.rs::backfill_stale_derivatives` — the selection, verbatim.
+    let backfilled: Vec<(Uuid, String, String)> = sqlx::query_as(
+        "SELECT id, original_path, mime_type FROM upload
+             WHERE deleted_at IS NULL AND mime_type LIKE 'image/%'
+               AND original_path IS NOT NULL
+               AND (
+                     (display_path IS NULL AND preview_path IS NOT NULL)
+                  OR derivatives_rev < $1
+               )",
+    )
+    .bind(1i16)
+    .fetch_all(&pool)
+    .await
+    .expect("backfill query");
+
+    assert!(
+        backfilled.is_empty(),
+        "a soft-deleted row must be invisible to the backfill, before or after sweeping"
     );
 }

docker-compose.yml

@@ -17,7 +17,15 @@ services:
     deploy:
       resources:
         limits:
-          memory: 512M
+          # 1G, not 512M. DATABASE_MAX_CONNECTIONS defaults to 30 for a ~100-guest event
+          # (feed polling + SSE + uploads at once), and 30 backends plus Postgres 16's
+          # default shared_buffers leaves very little headroom at 512M. An OOM here does
+          # not degrade one feature — it takes the event down, because every request
+          # path touches the database. Memory is the cheaper knob than shrinking the
+          # pool back and reintroducing the queueing it was raised to fix.
+          #
+          # Raising DATABASE_MAX_CONNECTIONS further means raising this too.
+          memory: 1G
 
   app:
     build:

e2e/fixtures/db.ts

@@ -105,6 +105,20 @@ export const db = {
     });
   },
 
+  /**
+   * Overstate an upload's recorded size.
+   *
+   * The keepsake size estimate and the low-disk threshold are pure SQL over
+   * `original_size_bytes` — no file is read — so this is the lever for driving "the keepsake
+   * would not fit" without a genuinely full disk. The bytes on disk are unchanged; only the
+   * accounting the warning reads from moves.
+   */
+  async setUploadSizeBytes(uploadId: string, bytes: number) {
+    await withClient((c) =>
+      c.query(`UPDATE upload SET original_size_bytes = $2 WHERE id = $1`, [uploadId, bytes])
+    );
+  },
+
   async setExportReleased(slug: string, released: boolean) {
     await withClient((c) =>
       c.query(`UPDATE event SET export_released_at = $2 WHERE slug = $1`, [

e2e/specs/03-feed/social-rate-limit.spec.ts

@@ -0,0 +1,136 @@
+/**
+ * Regression guard — likes, comments and comment deletions are rate limited.
+ *
+ * These were the only mutating endpoints in the app with no limit at all. Every other write path
+ * -- upload, join, recover, export, admin login -- carried 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 is contained:
+ * a like does fan an SSE broadcast to every connected client, but the export regeneration a
+ * comment deletion triggers is debounced (REGEN_DEBOUNCE 20s) and superseded workers are inert. So
+ * this closes the gap for symmetry, and the ceiling is set well above anything a real guest
+ * produces -- it bounds a script, not an enthusiastic double-tapper.
+ *
+ * The bucket is shared across all three actions on purpose: separate buckets would let a caller
+ * triple the aggregate write rate just by alternating between them. That is what the second test
+ * pins, and it is the part most likely to be lost in a refactor.
+ *
+ * Keyed per USER, not per IP — at a venue every guest is behind one NAT, so an IP key would hand
+ * the whole party one bucket. Third test.
+ */
+import { test, expect } from '../../fixtures/test';
+import { seedUpload } from '../../helpers/seed';
+import { BASE } from '../../helpers/env';
+
+const like = (jwt: string, uploadId: string) =>
+  fetch(`${BASE}/api/v1/upload/${uploadId}/like`, {
+    method: 'POST',
+    headers: { Authorization: `Bearer ${jwt}` },
+  });
+
+const comment = (jwt: string, uploadId: string, body: string) =>
+  fetch(`${BASE}/api/v1/upload/${uploadId}/comments`, {
+    method: 'POST',
+    headers: { Authorization: `Bearer ${jwt}`, 'Content-Type': 'application/json' },
+    body: JSON.stringify({ body }),
+  });
+
+test.describe('Social — rate limit', () => {
+  test('a burst of likes past the ceiling returns 429 with Retry-After', async ({
+    api,
+    adminToken,
+    guest,
+  }) => {
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      social_rate_enabled: 'true',
+      social_rate_per_min: '3',
+    });
+
+    const g = await guest('Tapper');
+    const uploadId = await seedUpload(g.jwt);
+
+    // Sequential, not parallel: a toggle flips state, so ordering matters for the assertion.
+    const statuses: number[] = [];
+    for (let i = 0; i < 5; i++) statuses.push((await like(g.jwt, uploadId)).status);
+
+    expect(statuses.slice(0, 3), 'the first three are within the ceiling').toEqual([200, 200, 200]);
+    expect(statuses.slice(3), 'everything past it is refused').toEqual([429, 429]);
+
+    const limited = await like(g.jwt, uploadId);
+    expect(limited.status).toBe(429);
+    expect(
+      limited.headers.get('retry-after'),
+      'a 429 without Retry-After tells the client nothing about when to come back'
+    ).toBeTruthy();
+  });
+
+  test('likes and comments share one bucket', async ({ api, adminToken, guest }) => {
+    // THE assertion. Per-action buckets would let a caller triple the aggregate write rate by
+    // alternating, which defeats the point of having a ceiling at all.
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      social_rate_enabled: 'true',
+      social_rate_per_min: '2',
+    });
+
+    const g = await guest('Mixer');
+    const uploadId = await seedUpload(g.jwt);
+
+    expect((await like(g.jwt, uploadId)).status).toBe(200);
+    expect((await comment(g.jwt, uploadId, 'schön!')).status).toBe(201);
+    // Two writes spent, whichever endpoints they went to.
+    expect(
+      (await comment(g.jwt, uploadId, 'noch eins')).status,
+      'a comment must consume the same budget a like does'
+    ).toBe(429);
+    expect((await like(g.jwt, uploadId)).status).toBe(429);
+  });
+
+  test('one guest hitting the ceiling does not block another', async ({
+    api,
+    adminToken,
+    guest,
+  }) => {
+    // Keyed per user, not per IP. Every request in this suite comes from one address, which is
+    // exactly the venue-NAT shape that made the /join and /feed limits turn guests away.
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      social_rate_enabled: 'true',
+      social_rate_per_min: '2',
+    });
+
+    const noisy = await guest('Noisy');
+    const quiet = await guest('Quiet');
+    const uploadId = await seedUpload(noisy.jwt);
+
+    for (let i = 0; i < 3; i++) await like(noisy.jwt, uploadId);
+    expect((await like(noisy.jwt, uploadId)).status).toBe(429);
+
+    expect(
+      (await like(quiet.jwt, uploadId)).status,
+      'a second guest behind the same IP must have their own budget'
+    ).toBe(200);
+  });
+
+  test('flipping social_rate_enabled off bypasses the limit', async ({
+    api,
+    adminToken,
+    guest,
+  }) => {
+    // The toggle has to actually be honoured, or the admin switch is decorative — the failure
+    // mode two other per-area toggles already shipped with.
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      social_rate_enabled: 'false',
+      social_rate_per_min: '2',
+    });
+
+    const g = await guest('Unlimited');
+    const uploadId = await seedUpload(g.jwt);
+
+    const statuses: number[] = [];
+    for (let i = 0; i < 6; i++) statuses.push((await like(g.jwt, uploadId)).status);
+    expect(statuses.every((s) => s === 200)).toBe(true);
+  });
+});

e2e/specs/04-host/low-disk-warning.spec.ts

@@ -0,0 +1,97 @@
+/**
+ * Regression guard — the host is warned about storage BEFORE it becomes unrecoverable.
+ *
+ * Storage visibility used to exist in exactly one place: a passive "Speicherauslastung" widget on
+ * the ADMIN dashboard. A host who isn't the admin had no view of it at all, and nothing anywhere
+ * warned anyone. README listed a low-disk alert under "Planned (v1.x)".
+ *
+ * Two things make that a safety net rather than a nice-to-have:
+ *
+ *  - `postgres_data`, `media_data` and `exports_data` are all Docker named volumes on ONE
+ *    filesystem. A full disk doesn't degrade a subsystem; Postgres stops being able to write and
+ *    the whole event goes down.
+ *  - The keepsake needs room for TWO gallery-sized archives (both write their media
+ *    `Compression::Stored`; `Memories.zip` streams the original for every video and every image
+ *    at or under 5 MB). The export preflight can refuse cleanly, but only AFTER the release —
+ *    when the event is over, the gallery is full, and every remedy is harder.
+ *
+ * So the threshold is deliberately NOT a fixed number alone. It fires on an absolute floor (10 GB,
+ * the figure the README always carried) OR on "you could not build the keepsake right now", which
+ * is the trigger a host can still act on.
+ *
+ * These drive it through `original_size_bytes` rather than a genuinely full disk: the estimate is
+ * pure SQL over that column, so overstating one row moves the accounting the warning reads without
+ * touching a byte on disk.
+ */
+import { test, expect } from '../../fixtures/test';
+import { seedUpload } from '../../helpers/seed';
+import { BASE } from '../../helpers/env';
+
+/** Comfortably larger than any disk this suite could run on. */
+const ABSURD_BYTES = 500_000_000_000_000;
+
+test.describe('Host — low-disk warning', () => {
+  test('a gallery too big to export warns the host, with the numbers', async ({
+    page,
+    host,
+    guest,
+    signIn,
+    db,
+  }) => {
+    const g = await guest('BigShooter');
+    const uploadId = await seedUpload(g.jwt);
+    await db.setUploadSizeBytes(uploadId, ABSURD_BYTES);
+
+    await signIn(page, host);
+    await page.goto('/host');
+
+    const warning = page.getByTestId('low-disk-warning');
+    await expect(warning, 'the host must be warned before releasing').toBeVisible({
+      timeout: 15_000,
+    });
+    // The actionable half: not just "low", but "the keepsake cannot be built".
+    await expect(warning).toContainText(/nicht.*erstellt werden/i);
+    // And the consequence that makes it urgent — the event, not just the download.
+    await expect(warning).toContainText(/gesamte Event/i);
+  });
+
+  test('the API reports the requirement and the verdict together', async ({ host, guest, db }) => {
+    const g = await guest('BigShooter2');
+    const uploadId = await seedUpload(g.jwt);
+    await db.setUploadSizeBytes(uploadId, ABSURD_BYTES);
+
+    const res = await fetch(`${BASE}/api/v1/host/event`, {
+      headers: { Authorization: `Bearer ${host.jwt}` },
+    });
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as {
+      disk_low: boolean;
+      disk_free_bytes: number | null;
+      keepsake_required_bytes: number;
+    };
+
+    expect(body.disk_low).toBe(true);
+    expect(
+      body.keepsake_required_bytes,
+      'both halves are armed by a release, so the requirement covers two archives'
+    ).toBeGreaterThan(ABSURD_BYTES);
+    expect(body.disk_free_bytes).not.toBeNull();
+    expect(body.keepsake_required_bytes).toBeGreaterThan(body.disk_free_bytes!);
+  });
+
+  test('an ordinary gallery shows no warning at all', async ({ page, host, guest, signIn }) => {
+    // The mirror that keeps the above honest. A warning that is always on is a warning nobody
+    // reads — and it would sit at the very top of the dashboard, above the PIN-reset queue.
+    const g = await guest('NormalShooter');
+    await seedUpload(g.jwt);
+
+    await signIn(page, host);
+    await page.goto('/host');
+
+    // Wait for the dashboard to actually be loaded before asserting on an absence.
+    await expect(page.getByRole('heading', { name: 'Host-Dashboard' })).toBeVisible({
+      timeout: 15_000,
+    });
+    await expect(page.getByTestId('low-disk-warning')).toHaveCount(0);
+  });
+});

frontend/src/routes/admin/+page.svelte

@@ -84,9 +84,16 @@
 				{ key: 'feed_rate_enabled', label: 'Feed-Limit aktiv', kind: 'bool' },
 				{ key: 'export_rate_enabled', label: 'Export-Limit aktiv', kind: 'bool' },
 				{ key: 'join_rate_enabled', label: 'Join-Limit aktiv', kind: 'bool' },
+				{ key: 'social_rate_enabled', label: 'Interaktions-Limit aktiv', kind: 'bool' },
 				{ key: 'upload_rate_per_hour', label: 'Upload-Limit pro Stunde', kind: 'number' },
 				{ key: 'feed_rate_per_min', label: 'Feed-Anfragen pro Minute', kind: 'number' },
-				{ key: 'export_rate_per_day', label: 'Export-Downloads pro Tag', kind: 'number' }
+				{ key: 'export_rate_per_day', label: 'Export-Downloads pro Tag', kind: 'number' },
+				{
+					key: 'social_rate_per_min',
+					label: 'Interaktionen pro Minute',
+					kind: 'number',
+					hint: 'Likes, Kommentare und Kommentar-Löschungen zusammen, pro Gast. Bewusst hoch angesetzt — soll ein Skript bremsen, keinen begeisterten Gast.'
+				}
 			]
 		},
 		{
@@ -105,7 +112,20 @@
 					kind: 'bool',
 					hint: 'Reserviert für künftige Anzahl-Limits.'
 				},
-				{ key: 'quota_tolerance', label: 'Toleranz (0–1)', kind: 'number' },
+				{
+					key: 'quota_tolerance',
+					label: 'Speicher-Anteil für Gäste (0–1)',
+					kind: 'number',
+					// "Toleranz (0–1)" with no hint invited exactly the wrong reading — that a higher
+					// number means "warn me later". It is the multiplier in
+					// `floor(freier Speicher × Anteil / aktive Uploader)`, so raising it authorises
+					// guests to fill MORE of the disk, not less.
+					hint:
+						'Anteil des freien Speichers, den alle Gäste zusammen belegen dürfen: ' +
+						'Limit = freier Speicher × Anteil ÷ aktive Uploader. Kein Warnschwellenwert — ' +
+						'ein höherer Wert gibt MEHR Speicher frei. Das Keepsake braucht zusätzlich ' +
+						'etwa das Doppelte der Mediengröße; 0,75 ist der getestete Standard.'
+				},
 				{ key: 'estimated_guest_count', label: 'Geschätzte Gästezahl', kind: 'number' }
 			]
 		},

frontend/src/routes/host/+page.svelte

@@ -28,6 +28,9 @@
 		is_active: boolean;
 		uploads_locked: boolean;
 		export_released: boolean;
+		disk_free_bytes: number | null;
+		keepsake_required_bytes: number;
+		disk_low: boolean;
 	}
 
 	interface PinResetRequest {
@@ -395,7 +398,11 @@
 	function formatBytes(bytes: number): string {
 		if (bytes < 1024) return `${bytes} B`;
 		if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
-		return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+		// GB matters here now that this also renders free disk and keepsake size — the previous
+		// version topped out at MB, so 30 GB free read as "30720.0 MB" (and a guest with 2 GB of
+		// uploads was already being rendered the same way in the user list).
+		if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+		return `${(bytes / (1024 * 1024 * 1024)).toFixed(1)} GB`;
 	}
 </script>
 
@@ -507,6 +514,38 @@
 				{error}
 			</div>
 		{:else if event}
+			<!-- ── Speicherwarnung ─────────────────────────────────────────────
+			     Above everything else on purpose. All three volumes (postgres_data, media_data,
+			     exports_data) sit on one filesystem, so running out doesn't degrade a subsystem —
+			     it stops Postgres writing and takes the event down. And the keepsake needs room
+			     for TWO gallery-sized archives, which is only actionable BEFORE the release: the
+			     export preflight can say "this didn't fit", but by then the event is over and the
+			     remedies are all much harder.
+
+			     Only the admin dashboard had any storage visibility at all, and a host is often
+			     not the admin. `disk_low` fails closed to "not low" on an unreadable mount, so
+			     this cannot cry wolf. -->
+			{#if event.disk_low && event.disk_free_bytes !== null}
+				<div
+					class="rounded-xl border border-red-300 bg-red-50 p-4 dark:border-red-800 dark:bg-red-950/30"
+					data-testid="low-disk-warning"
+				>
+					<h2 class="font-semibold text-red-900 dark:text-red-200">Speicherplatz wird knapp</h2>
+					<p class="mt-1 text-sm text-red-800 dark:text-red-300">
+						Noch <strong>{formatBytes(event.disk_free_bytes)}</strong> frei.
+						{#if event.keepsake_required_bytes > event.disk_free_bytes}
+							Für das Keepsake werden derzeit ca.
+							<strong>{formatBytes(event.keepsake_required_bytes)}</strong> benötigt — es kann
+							momentan <strong>nicht</strong> erstellt werden.
+						{/if}
+					</p>
+					<p class="mt-1.5 text-xs text-red-700 dark:text-red-400">
+						Schaffe Speicher frei oder vergrößere den Datenträger. Wenn der Datenträger vollläuft,
+						fällt das gesamte Event aus — nicht nur der Download.
+					</p>
+				</div>
+			{/if}
+
 			<!-- ── PIN-Reset-Anfragen ──────────────────────────────────────── -->
 			{#if pinResetRequests.length > 0}
 				<div