fix(rereview): close residual export finalize↔flip double-race at reopen

Adversarial re-review of df275bb found the two-guard ready-flip fix still left a
narrow double-race open, plus test-hygiene drift from the banUser param removal.

MED — residual stale-keepsake race the `export_released_at` guard alone missed
  The flip relied on two guards defeating two clearers: the `release_seq` EXISTS
  check (vs a re-release bump) and `export_released_at IS NOT NULL` (vs open_event's
  clear). But release_gallery re-arms `export_released_at = NOW()` and bumps
  `release_seq` as SEPARATE statements, so a stale worker's flip landing in the gap
  between them satisfies BOTH guards (released re-armed, seq not yet bumped) and
  resurrects a pre-reopen keepsake — the next re-release then skips regeneration and
  serves an archive missing the reopen-window uploads.

  Root-cause fix: `open_event` now bumps every `export_job.release_seq`, making a
  reopen a supersession point symmetric with a re-release. A worker that captured the
  pre-reopen seq can never match its `release_seq`-guarded finalize/flip again,
  regardless of when the re-release re-arms `export_released_at`. The released-anchor
  guard stays as defense-in-depth. Added a deterministic e2e asserting the reopen
  bumps the seq (the invariant that closes the race without depending on
  sub-millisecond worker timing).

LOW
  - Gate the `export-progress: 100` SSE + `prune_stale_export_files` on the ready-flip
    actually flipping (rows_affected > 0). A superseded worker no longer advertises a
    misleading 100% or prunes on a fresh generation's behalf.
  - moderation.spec.ts: the two ban tests had become byte-identical after the
    hide_uploads param removal; drop the one whose "hide_uploads=true" title no longer
    matched what it exercised, keep the accurate "always hides" test.
  - host-dashboard page-object: drop the dead `banUser(hideUploads)` param + its
    checkbox branch (the UI no longer renders that checkbox — a latent hang trap).
  - sse-eviction.spec.ts: rename the test whose title referenced the removed flag.

Verified: backend 40 tests, e2e 156 passed / 1 skipped on chromium-desktop
(incl. the new reopen-supersession regression).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

e2e/specs/04-host/moderation.spec.ts

@@ -7,18 +7,9 @@ import { test, expect } from '../../fixtures/test';
 import { seedUpload, seedComment } from '../../helpers/seed';
 
 test.describe('Host — moderation API', () => {
-  test('ban with hide_uploads=true sets the right flags', async ({ api, host, guest }) => {
-    const target = await guest('Banned1');
-    await api.banUser(host.jwt, target.userId);
-    const users = await api.listUsers(host.jwt);
-    const row = users.find((u: any) => u.id === target.userId);
-    expect(row?.is_banned).toBe(true);
-    expect(row?.uploads_hidden).toBe(true);
-  });
-
-  test('ban always hides — the hide_uploads flag is ignored (USER_JOURNEYS §10.5)', async ({ api, host, guest }) => {
-    // Ban is now unconditionally a hide: even asking NOT to hide still hides, because a
-    // banned user's content is "gone" everywhere. The legacy hide_uploads arg is ignored.
+  test('ban always hides — a banned user is is_banned AND uploads_hidden (USER_JOURNEYS §9.5)', async ({ api, host, guest }) => {
+    // Ban is unconditionally a hide: a banned user's content is "gone" everywhere. The endpoint
+    // takes no body and there is no per-request opt-out (the legacy hide_uploads flag is gone).
     const target = await guest('Banned2');
     await api.banUser(host.jwt, target.userId);
     const users = await api.listUsers(host.jwt);

e2e/specs/04-host/sse-eviction.spec.ts

@@ -30,7 +30,7 @@ test.describe('Host — live SSE eviction (H3)', () => {
     );
   });
 
-  test('banning a user with hide_uploads broadcasts user-hidden', async ({
+  test('banning a user broadcasts user-hidden', async ({
     api,
     host,
     guest,

e2e/specs/10-flow-review/export-reopen-rerelease.spec.ts

@@ -18,23 +18,23 @@
  * download follows the current `done` row's `file_path`, never a fixed name.
  *
  * A second, narrower window on the SAME class of bug (fixed alongside): a reopen (`open_event`)
- * landing between a *current* worker's `finalize_job` and its ready-flag flip. `open_event`
- * clears `export_released_at` + both ready flags but leaves the `export_job` row `done` at the
- * current seq — so the seq-guarded flip would still match and resurrect `export_zip_ready=TRUE`
- * on a pre-reopen snapshot, and the next re-release would `if ready { continue }` and skip
- * regeneration. The flip UPDATEs are therefore additionally anchored on
- * `export_released_at IS NOT NULL`, making them a no-op once a reopen has landed. The
- * "completeness" test below exercises the real reopen→re-release worker path end-to-end; the
- * sub-millisecond finalize↔flip interleave itself isn't deterministically forceable with the
- * fast fixtures, so that exact window is covered by the SQL guard + code review rather than a
- * timing-dependent assertion.
+ * landing between a *current* worker's `finalize_job` and its ready-flag flip could resurrect
+ * `export_zip_ready=TRUE` on a pre-reopen snapshot, and the next re-release would
+ * `if ready { continue }` and skip regeneration. Two layers close it: (1) `open_event` now bumps
+ * every `export_job.release_seq`, so a reopen is itself a supersession point — a stale worker's
+ * captured seq no longer matches its `release_seq`-guarded flip; (2) the flip UPDATEs are also
+ * anchored on `export_released_at IS NOT NULL` as belt-and-suspenders. Layer (1) is what defeats
+ * the double-race where a re-release re-arms `export_released_at` before it bumps the seq.
  *
  * Coverage:
  *  - churn integrity: rapid reopen→re-release yields exactly one INTACT ZIP, no stuck jobs.
  *  - completeness: an upload added during the reopen window IS present in the re-released
  *    keepsake (the direct data-loss regression).
- *  - supersession: a re-release SUPERSEDES an in-flight (running) job — it bumps the
+ *  - supersession (re-release): a re-release SUPERSEDES an in-flight (running) job — it bumps the
  *    generation and regenerates, rather than leaving the stale worker to finalize.
+ *  - supersession (reopen): a reopen ALONE bumps the generation, so a worker holding the
+ *    pre-reopen seq can never flip a stale ready flag (closes the finalize↔flip double-race
+ *    deterministically, without depending on sub-millisecond worker timing).
  */
 import { test, expect } from '../../fixtures/test';
 import { Client } from 'pg';
@@ -209,7 +209,8 @@ test.describe('Flow re-review — reopen→re-release export integrity + stale-k
         WHERE e.id = ej.event_id AND e.slug = '${SLUG}' AND ej.type = 'zip'`
     );
 
-    // Reopen (clears release + ready flags; does NOT touch job rows) then re-release.
+    // Reopen (clears release + ready flags AND bumps every export_job's release_seq) then
+    // re-release (bumps + resets again). Either bump alone supersedes the pinned running row.
     expect((await post('/api/v1/host/event/open', host.jwt)).status).toBe(204);
     expect((await post('/api/v1/host/gallery/release', host.jwt)).status).toBe(204);
 
@@ -227,4 +228,41 @@ test.describe('Flow re-review — reopen→re-release export integrity + stale-k
       seqBefore
     );
   });
+
+  test('a reopen ALONE bumps release_seq — a pre-reopen worker can never flip a stale ready flag', async ({
+    host,
+  }) => {
+    // Deterministic proof of the reopen-supersession that closes the finalize↔flip double-race.
+    // The nasty interleaving (worker finalized `done@S`, THEN reopen, THEN a re-release re-arms
+    // `export_released_at` BEFORE it bumps the seq, THEN the stale worker's flip runs and both
+    // guards pass) can't be forced by sub-millisecond timing — but its ROOT cause is observable:
+    // whether a reopen retires the current generation's seq. If it does, the seq the worker
+    // captured (S) is gone for good, so its `release_seq = S`-guarded flip matches nothing no
+    // matter when it lands. We assert exactly that invariant.
+    await seedUpload(host.jwt, { caption: 'x' });
+    expect((await post('/api/v1/host/gallery/release', host.jwt)).status).toBe(204);
+    await waitExportDone(host.jwt);
+    const seqAtRelease = await zipReleaseSeq();
+
+    // Reopen only — no re-release. The export_job row is left `done` at the OLD seq by the old
+    // code; the fix bumps it here.
+    expect((await post('/api/v1/host/event/open', host.jwt)).status).toBe(204);
+
+    const seqAfterReopen = await zipReleaseSeq();
+    expect(
+      seqAfterReopen,
+      'reopen must bump export_job.release_seq so a pre-reopen worker (seq=' +
+        seqAtRelease +
+        ') is superseded and can never flip a stale ready flag'
+    ).toBeGreaterThan(seqAtRelease);
+
+    // And the reopen must have cleared readiness (belt-and-suspenders: the stale worker also
+    // can't satisfy `export_released_at IS NOT NULL`).
+    const [ev] = await pgQuery<{ zip_ready: boolean; released_at: string | null }>(
+      `SELECT export_zip_ready AS zip_ready, export_released_at AS released_at
+         FROM event WHERE slug = '${SLUG}'`
+    );
+    expect(ev.zip_ready, 'reopen clears zip readiness').toBe(false);
+    expect(ev.released_at, 'reopen clears the release timestamp').toBeNull();
+  });
 });