feat(bg-notifier): B-0501 slice 5a — assignment-history cooldown gate

docs/BACKLOG.md

@@ -305,7 +305,7 @@ are closed (status: closed in frontmatter)._
 - [ ] **[B-0496](backlog/P1/B-0496-hamiltonian-viz-slice-2-live-github-api-2026-05-14.md)** Hamiltonian viz — slice-2: live GitHub API commit fetch → trajectory
 - [ ] **[B-0497](backlog/P1/B-0497-b0440-slice-6-standing-by-detector-launchd-registration-2026-05-14.md)** B-0440 slice 6 — standing-by-detector launchd plist + AUTONOMOUS-LOOP.md wiring update
 - [x] **[B-0500](backlog/P1/B-0500-b0441-slice-3-queue-state-guard-poll-once-wiring-2026-05-14.md)** B-0441 slice 3 — wire isAgentQueueEmpty guard into pollOnce
-- [ ] **[B-0501](backlog/P1/B-0501-b0441-slice-5-assignment-history-dedup-cooldown-2026-05-14.md)** B-0441 slice 5 — assignment history dedup cooldown (avoid re-assigning same row within short window)
+- [x] **[B-0501](backlog/P1/B-0501-b0441-slice-5-assignment-history-dedup-cooldown-2026-05-14.md)** B-0441 slice 5 — assignment history dedup cooldown (avoid re-assigning same row within short window)
 - [ ] **[B-0502](backlog/P1/B-0502-b0441-slice-6-launchd-plist-autonomous-loop-docs-2026-05-14.md)** B-0441 slice 6 — launchd plist for backlog-ready-notifier + AUTONOMOUS-LOOP.md update
 - [x] **[B-0503](backlog/P1/B-0503-b0442-slice5a-open-recovery-pr-core-function-2026-05-14.md)** B-0442 slice 5a — openRecoveryPR core function + RecoveryAdapters + DST tests
 - [x] **[B-0504](backlog/P1/B-0504-b0442-slice5b-wire-auto-recover-into-pollonce-2026-05-14.md)** B-0442 slice 5b — wire --auto-recover into pollOnce + real RecoveryAdapters + config flags

docs/backlog/P1/B-0441-backlog-row-ready-to-grind-notifier-background-service-2026-05-13.md

@@ -50,8 +50,8 @@ provides a less-ambiguous concrete claim — eliminating the
          decompositionSuggestion: <slice-breakdown> } }` (Slice 4, shipped)
 - [x] Honors agent autonomy — assignment is suggestion, not directive
       (per `.claude/rules/no-directives.md`) — by design; envelope is advisory
-- [ ] Tracks assignment history to avoid re-assigning same row
-      within short window (Slice 5a, B-0501 open — `historyFile`/cooldown logic not yet in `tools/bg/backlog-ready-notifier.ts`)
+- [x] Tracks assignment history to avoid re-assigning same row
+      within short window (Slice 5a, B-0501 shipped — `historyFile`/`cooldownMin` config + read/write adapters + cooldown-gate logic in `tools/bg/backlog-ready-notifier.ts`; 8 new tests cover skip-within-window / re-assign-after-window / first-assignment / multi-row-mix / pruning)
 - [x] Tests cover the readiness-detection heuristics
       (`tools/bg/backlog-ready-notifier.test.ts`)
 - [x] Documented in `docs/AUTONOMOUS-LOOP.md`

docs/backlog/P1/B-0501-b0441-slice-5-assignment-history-dedup-cooldown-2026-05-14.md

@@ -1,12 +1,12 @@
 ---
 id: B-0501
 priority: P1
-status: open
+status: closed
 title: "B-0441 slice 5 — assignment history dedup cooldown (avoid re-assigning same row within short window)"
 tier: factory-infrastructure
 effort: S
 created: 2026-05-14
-last_updated: 2026-05-14
+last_updated: 2026-05-20
 parent: B-0441
 depends_on: []
 composes_with: [B-0441, B-0500, B-0502]
@@ -28,34 +28,44 @@ busy. This produces noisy bus output and makes the assignment signal less meanin
 
 ## Acceptance criteria
 
-- [ ] `NotifierConfig` gains a `historyFile` field (default
+- [x] `NotifierConfig` gains a `historyFile` field (default
       `"/tmp/zeta-bus/assignment-history.json"`; respects `ZETA_BUS_DIR` if set)
       and a `cooldownMin` field (default `30`)
-- [ ] Before publishing a work-assignment envelope for a given `rowId`, check the
+- [x] Before publishing a work-assignment envelope for a given `rowId`, check the
       history file:
   - If `rowId` appears in the history with a timestamp within `cooldownMin` minutes
     of `now()` → skip that row (do not publish)
   - If absent or expired → publish and record `{ rowId, publishedAt: now().toISOString() }`
-- [ ] After publishing, write the updated history back to `historyFile`:
+- [x] After publishing, write the updated history back to `historyFile`:
   - Prune entries older than `cooldownMin` before writing to bound file size
   - Use atomic write (write to `<historyFile>.tmp` then rename) to survive concurrent
     access from multiple notifier instances
-- [ ] `PollResult` gains a `skippedDueToCooldown: string[]` field listing any `rowId`s
+- [x] `PollResult` gains a `skippedDueToCooldown: string[]` field listing any `rowId`s
       that were skipped because of cooldown
-- [ ] Adapters interface gains:
+- [x] Adapters interface gains:
   - `readHistoryFile: (path: string) => AssignmentHistory | null`
     (returns null when file absent or unreadable)
   - `writeHistoryFile: (path: string, history: AssignmentHistory) => void`
   - Tests inject fake implementations; production uses `REAL_ADAPTERS` with
     `fs.readFileSync` / atomic-rename write
-- [ ] Tests added (DST-replayable with injected adapters):
+- [x] Tests added (DST-replayable with injected adapters):
   - Row assigned at T=0; same row at T=15min (within 30min cooldown) → skipped
   - Row assigned at T=0; same row at T=35min (after 30min cooldown) → re-assigned
   - History file absent → treated as empty; first assignment proceeds normally
   - Multiple rows in cooldown → only expired rows published; `skippedDueToCooldown`
     lists skipped IDs
   - History pruning: entries older than `cooldownMin` removed on write
 
+## Resolution
+
+Shipped in this PR. 8 new tests (45 total) cover all acceptance criteria + bonus
+coverage of `defaultHistoryFile()` honoring `ZETA_BUS_DIR` + new `--history-file`
+and `--cooldown-min` CLI flags. REAL_ADAPTERS uses atomic-rename via
+`renameSync(tmp, path)` after `writeFileSync(tmp, ...)`. Default config resolves
+the history-file path at module-load time via `defaultHistoryFile()` honoring
+`process.env.ZETA_BUS_DIR`. B-0441 parent acceptance criterion "Tracks assignment
+history to avoid re-assigning same row within short window" is now satisfied.
+
 ## Design sketch
 
 ```typescript