feat(logs): app log store — backend pino DB sink + frontend error collection

Add a third data stream (app_logs), distinct from the signed ledger and device
telemetry, for operational/diagnostic logs — an offline appliance has no Sentry to
ship to, so the host is the log store.

Backend: a pino stream tees warn/error/fatal into app_logs (info/debug stay
stdout-only) with no call-site change; the DB is built before Fastify so the logger
has its sink. Frontend (lib/logger.ts): ships failed API requests (minus 401 churn),
window.onerror, unhandledrejection, and a top-level React ErrorBoundary; console
warn/error forwarded only at debug/trace. Batched/throttled POST, sendBeacon on
pagehide, loop-safe (never logs the /api/logs call), best-effort everywhere.

POST /api/logs (any signed-in user, CSRF, tolerant) + GET /api/logs gated by a new
log:read permission (new `log` RBAC resource; admin holds it). Retention: pruned by
age + row cap, hourly + at startup. UI: a Logs screen under /setup (filter
level/source/since, expand to context+stack), sq+en. Migration 0009_app_logs.

Verified end-to-end via app.inject: login -> POST 204 -> GET 200 with the record;
backend warn/error persisted, info dropped; non-admin GET 403 / POST 204.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

wiki/concepts/app-logs.md

@@ -0,0 +1,101 @@
+---
+type: concept
+tags: [parking, observability, diagnostics, logging, frontend, backend]
+sources: []
+updated: 2026-06-19
+status: open
+---
+
+# Application logs (diagnostics) — the third stream
+
+A **third data stream**, deliberately distinct from the two in [[event-streams-split]]:
+
+| Stream | Table | Signed? | Purpose |
+| --- | --- | --- | --- |
+| Business ledger | `ledger_events` | ✅ ATECC608 | money/accountability ([[append-only-event-chain]]) |
+| Device telemetry | `device_events` | ❌ | hardware chatter ([[device-events]]) |
+| **App logs** | **`app_logs`** | ❌ | **operational/diagnostic logs** (this page) |
+
+App logs answer *"why did the booth misbehave?"* — a question neither of the other streams should
+absorb (logs are neither business facts nor hardware telemetry). On an **offline appliance** there's
+no Sentry/Datadog to ship to, so the host **is** the log store: backend warnings/errors AND frontend
+errors land in one queryable table, viewable at the booth. Built 2026-06-19.
+
+## What's captured
+
+- **Backend `warn` / `error` / `fatal`** — a pino stream tees these into `app_logs` (and still writes
+  them to stdout, unchanged). `info`/`debug`/`trace` stay **stdout-only** — they'd bloat the DB. So
+  every `app.log.warn/error(...)` already in the codebase is now persisted with **no call-site
+  change**.
+- **Frontend errors** (always): every **failed API request** (`apiFetch`'s non-OK path → method,
+  path, status, server error body — except `401`, which is normal pre-login churn), every **uncaught
+  error** (`window.onerror`), every **unhandled promise rejection**, and a top-level **React
+  ErrorBoundary** (a render crash is reported as `fatal` instead of a white screen).
+- **`console.warn` / `console.error`** — only forwarded when the **client log level is `debug`/`trace`**
+  (off by default; they're noisy with third-party chatter). The high-signal sources above are always
+  on. Toggle via `VITE_LOG_LEVEL` / `setClientLogLevel()`.
+
+## Shape
+
+`app_logs`: `level` (pino names), `source` (`frontend`|`backend`), `message`, `context` (one JSON
+column — the failed request, error name, component stack, anything), plus pulled-out `httpStatus` /
+`path` for cheap filtering, `stack`, `userId`, `userAgent`, `createdAt`. Indexed on `created_at` +
+`level`. Shared types: `AppLogRecord` / `ClientLogInput` / `LogLevel` in `@parking/shared`.
+
+## The API + the access split
+
+- **`POST /api/logs`** — the frontend ships errors here. **Any signed-in user** may write (it's their
+  own browser's diagnostics) — `requireAuth`, not a permission. CSRF still applies (it's a mutation).
+  Accepts one entry or a `{ entries: [...] }` batch (capped at 50). **Deliberately never 4xx's on a
+  malformed entry** — a client erroring *while reporting an error* must not get a second error.
+- **`GET /api/logs`** — read the store (level/source/since filters), gated by the **new `log:read`
+  permission** (a new `log` resource in the dynamic [[local-jwt-auth|RBAC]] grid). Admin holds it;
+  it's grantable to a diagnostic role. *Verified: a cashier without `log:read` gets 403 on GET but
+  204 on POST — the intended asymmetry.*
+
+## Reliability invariants (a logger must never make things worse)
+
+- **No infinite loop.** The frontend collector never logs the `/api/logs` request itself, and flushes
+  via **raw `fetch`/`sendBeacon`**, not `apiFetch` (so a flush failure can't recurse into a new log).
+  The backend `LogService` has a **reentrancy guard** — persisting a log can't emit a persisted log.
+- **Best-effort, never fatal.** Every write is wrapped; a DB/logging failure is swallowed (it can't be
+  logged — that's the recursion we guard). Diagnostics must never break the path they observe.
+- **Bounded.** Frontend queue capped (drops oldest); message/stack/context clamped per row;
+  ingest batch capped.
+
+## Retention (offline appliance ⇒ must be bounded)
+
+Pruned by **age AND a row cap** (a burst could blow past an age-only window): delete older than
+`LOG_RETENTION_DAYS` (default 30) **and** keep only the newest `LOG_RETENTION_MAX_ROWS` (default
+50 000). Runs **hourly** (unref'd timer) + once at startup. Both env-configurable. Same "prunable,
+not precious" durability class as `device_events` — the opposite of the append-only ledger.
+
+## The booth viewer
+
+A **Logs screen** under Setup (`/setup/logs`, gated by `log:read`, sq+en) — filter by
+level/source/since, newest first, each row expands to the structured `context` + stack. Read-only
+(logs are evidence, never edited). Polls every 15 s (no WS — diagnostics aren't latency-critical).
+Sits alongside the other admin tabs in [[booth-console]].
+
+## As-built (2026-06-19)
+
+- `packages/db`: `app_logs` table + migration `0009_app_logs.sql` (+ journal idx 9; seeds admin
+  `log:read`). Applied to the live `apps/server/parking.sqlite`.
+- `@parking/shared`: `log` resource + `log:read` permission; `LogLevel`/`LogSource`/`AppLogRecord`/
+  `ClientLogInput`/`LOG_LEVEL_ORDER`.
+- `apps/server`: `log-service.ts` (`LogService` + `pinoDbStream`), `routes/logs.ts`, wired in
+  `server.ts` (DB built before Fastify so the pino stream has the sink; prune timer).
+- `apps/web`: `lib/logger.ts` (collector + global handlers), `lib/ErrorBoundary.tsx`, `apiFetch` hook,
+  `LogsViewer.tsx` + route/nav, i18n.
+
+## Open
+
+- **No automated test** (the standing harness gap) — though the ingest/read/gate path was verified by
+  in-process `app.inject` smoke (login → POST 204 → GET 200 with the record; non-admin 403/204 split).
+- **Server API error strings stay English** — unchanged here; this is about *persisting* logs, not
+  localizing them. The localized-ledger-reason pattern ([[i18n]]) is the template if log *display*
+  ever needs translation (currently the message is whatever the thrower wrote).
+- **Surfacing critical logs live** — a `fatal`/`error` count badge on the booth footer over the
+  existing `/api/ws` could flag problems without opening the viewer. Deferred.
+- **Correlation id** — no request-id threads a frontend failed-request log to its backend log yet;
+  add a `x-request-id` echo if cross-stream correlation is wanted.