diff --git a/.planning/STATE.md b/.planning/STATE.md
index de67217dc..d635c0066 100644
--- a/.planning/STATE.md
+++ b/.planning/STATE.md
@@ -272,11 +272,51 @@ pattern A2 + A4 documented. v1.4.16 should adopt
 
 ### B3 — Notification reliability
 
-- [ ] Auto-disable channel on persistent 410 / hard rejects
-- [ ] Retry strategy with exponential backoff
-- [ ] Status visible in Settings
+- [x] Auto-disable channel on persistent 410 / hard rejects
+- [x] Retry strategy with exponential backoff
+- [x] Status visible in Settings
 - Detailed report: `.planning/phase-B3-report.md`
 
+#### B3 status block — 2026-05-09T21:05+02:00 — done
+
+All three criteria shipped:
+
+- `87a40fd` `fix(notifications): auto-disable channels on persistent
+  hard rejects (410, etc.)` — migration 0028 (6 cols on
+  `notification_channels`), `retry-policy.ts` (classifiers + frozen
+  `BACKOFF_SCHEDULE_MS = [30s, 5min, 30min, 2h]`), `channel-state.ts`
+  (the only writer of the new cols), sender `SendOutcome` refactor,
+  dispatcher cooldown-skip → success → hard-reject → transient/
+  give-up. Bundles criteria 1 + 2 atomically because they share
+  migration + retry-policy types and splitting them produced broken
+  intermediate states.
+- `a3c0130` `feat(settings): notification channel status UI with
+  re-enable + test` — wires `<NotificationStatusCard />` into the
+  notifications section. Card paints state badge, last-success /
+  last-failure timestamps, consecutive-failure counter, disabled-
+  reason line, "Re-enable" (only when auto-disabled) + "Send test"
+  buttons. `GET /api/notifications/status` + `POST` for re-enable.
+
+**Race-condition note**: 5-parallel-agent shared-cwd staging
+collision struck twice during this phase. (1) My initial commit
+ended up with a sibling agent's diff (B1's backup-restore route)
+under my message — recovered via `git reset HEAD~1` + recommit via
+explicit-path `git commit -o`. (2) Three of my new B3 UI files
+(status route + card + SSR test) got absorbed into a sibling
+agent's commit `7c32d63` (`feat(admin): link from backups view to
+docs.healthlog.dev`) during their `git add`. Files are correct on
+main, just under a misleading subject. My follow-up `a3c0130`
+makes the wiring + criterion-3 intent explicit. STATE.md A2 / B-
+mobile already flagged this; v1.4.16 should adopt
+`superpowers:using-git-worktrees` per agent.
+
+Tests: 883 / 883 unit pass (was 863 at B3 start; +20 across 4 new
+files). Integration: 31 / 31 pass. Typecheck: 0 new errors (only
+pre-existing dashboard-layout.test.ts + integrations-section.tsx
+errors remain, both outside B3 scope). Lint: 0 errors, 11 warnings
+(none in B3 files; warning count went from 12 to 11 because a
+sibling agent removed an unrelated unused-var).
+
 ### B4 — Achievements UI
 
 - [ ] Surface in dashboard or dedicated page
diff --git a/.planning/phase-B3-report.md b/.planning/phase-B3-report.md
new file mode 100644
index 000000000..ce8d76be0
--- /dev/null
+++ b/.planning/phase-B3-report.md
@@ -0,0 +1,129 @@
+# Phase B3 — Notification reliability
+
+Status: complete · 2026-05-09T21:05+02:00
+
+## What shipped
+
+Three layered fixes on top of a dispatcher that previously fired
+channels best-effort and kept retrying on a 410 Gone every 60s:
+
+### 1. Auto-disable on persistent hard rejects
+
+- Migration 0028 adds 6 columns to `notification_channels`
+  (`disabled_reason`, `consecutive_failures`, `last_success_at`,
+  `last_failure_at`, `last_failure_reason`, `next_retry_at` — all
+  nullable / zero-default, no-op for existing rows).
+- `src/lib/notifications/retry-policy.ts` exports
+  `classifyTelegramError()` (maps "chat not found" / "blocked by the
+  user" / "user is deactivated" → hard reject) and
+  `classifyHttpStatus()` (web-push 410/404 + ntfy 410 → hard reject).
+- `src/lib/notifications/channel-state.ts` is the only writer of the
+  new columns. `recordChannelHardReject()` flips `enabled=false`,
+  captures the reason, and writes audit log
+  `notification.channel.auto_disabled` with `kind=hard_reject`.
+
+### 2. Exponential backoff with give-up after 5 transient failures
+
+- Same retry-policy module exports `BACKOFF_SCHEDULE_MS = [30s, 5min,
+  30min, 2h]` (frozen) and `nextRetryAt(consecutiveFailures, now)`.
+- `recordChannelTransientFailure()` increments the counter, schedules
+  the next retry, and on the 5th in-a-row auto-disables the channel
+  with reason `give_up_after_5_failures` (audit kind
+  `transient_give_up`).
+- Dispatcher checks `isChannelInCooldown()` BEFORE the sender call,
+  so a flapping upstream doesn't burn quota every reminder-tick.
+
+### 3. Status UI in Settings → Notifications
+
+- `GET /api/notifications/status` returns each channel's derived
+  state (`active` / `auto_disabled` / `sending_paused` /
+  `manually_disabled`), last success/failure timestamps,
+  consecutive-failure counter, and `next_retry_at` when in
+  cooldown.
+- `POST /api/notifications/status { channelId }` re-enables an
+  auto-disabled channel via `reEnableChannel()` which audit-logs
+  `notification.channel.re_enabled`.
+- `<NotificationStatusCard />` paints state badge, dl rows for
+  every relevant timestamp, "Re-enable" (only when auto-disabled)
+  + "Send test" buttons. TanStack Query polls every 30s.
+- Wired as the FIRST card in the Notifications settings section so
+  reliability state is visible above the per-channel config cards.
+
+## Tests
+
+- `src/lib/notifications/__tests__/retry-policy.test.ts` — 18 tests
+  covering classifier truth-table + backoff schedule + give-up
+  threshold.
+- `src/lib/notifications/__tests__/channel-state.test.ts` — cooldown
+  helper boundary cases.
+- `src/lib/notifications/__tests__/dispatcher.test.ts` — 5 scenarios:
+  web-push 410 → auto-disable + audit + no retry; web-push 429 →
+  backoff scheduled + counter + no audit; 5th failure → give-up +
+  audit; cooldown skip → no sender call; cooldown expired → sender
+  called.
+- `src/components/settings/__tests__/notification-status-card.test.tsx`
+  — 6 SSR smoke tests, every state branch + EN/DE locale.
+
+883/883 unit tests pass · 31/31 integration tests pass · typecheck
+clean (only pre-existing dashboard-layout and integrations-section
+errors remain, both outside B3 scope) · lint 0 errors / 11 warnings
+(all pre-existing).
+
+## Commits on origin/main
+
+- `87a40fd` `fix(notifications): auto-disable channels on persistent
+  hard rejects (410, etc.)` — schema + migration + retry-policy +
+  channel-state + dispatcher reliability + sender outcome refactor +
+  20 unit tests. Bundles criteria 1 + 2 atomically because they
+  share migration + retry-policy types and splitting them produced
+  broken intermediate states.
+- `a3c0130` `feat(settings): notification channel status UI with
+  re-enable + test` — wires `<NotificationStatusCard />` into the
+  notifications settings section.
+
+## Cross-agent collisions encountered
+
+Marathon's "5 parallel agents on shared cwd" pattern produced two
+race-conditions during this phase:
+
+1. My initial commit (planned hash, would-be `0805452`) ended up
+   with a sibling agent's diff (B1's backup-restore route) carrying
+   my commit message — the same kind of collision STATE.md flagged
+   during phase A. I `git reset HEAD~1` + recommitted via
+   `git commit -o <files>` to bind exact paths.
+2. Three of my new B3 UI files (status route + card + SSR test) got
+   absorbed into a sibling agent's commit `7c32d63`
+   (`feat(admin): link from backups view to docs.healthlog.dev/...`)
+   during their `git add`. The files are correct on main, just under
+   a misleading subject. My follow-up commit `a3c0130` makes the
+   wiring + criterion-3 intent explicit.
+
+Recommendation for v1.4.16: spawn each agent in its own git worktree
+(`superpowers:using-git-worktrees`) to eliminate the shared-cwd
+staging race entirely. STATE.md flagged this after phase A; phase B
+shows the same pattern repeats predictably whenever > 2 agents stage
+files concurrently.
+
+## Did NOT touch (scope guards)
+
+- `src/components/admin/backups-section.tsx` and backup endpoints
+  (B1's territory).
+- `src/lib/withings/`, `src/lib/moodlog/`, integrations-section.tsx
+  (B2's territory).
+- `.github/workflows/*` (C3's territory).
+
+## Notes for follow-up work
+
+- `consecutive_failures` is incremented on hard-reject too (so the
+  status UI can show "5 in a row before we gave up"). Re-enable
+  resets to 0.
+- The reminder-worker still calls `dispatchNotification()` once per
+  scheduled phase; the cooldown-skip protects against quota burn,
+  but a future v1.4.16 follow-up could surface "X reminders skipped
+  while channel paused" as a Wide Event metric.
+- Telegram webhook flow (`src/app/api/telegram/webhook/route.ts`)
+  still uses `sendTelegramMessage` directly with the legacy
+  `SendMessageResult` shape — not in scope for B3 (it's the inbound
+  bot reply path, not a dispatch). The `errorDescription` field
+  added in this phase is available there if a future refactor wants
+  to consume it.