# Tasks: logger-silent-failure-fix

## 1. Spec delta

- [x] 1.1 Author `specs/logging/spec.md` delta with `## MODIFIED Requirements` (LG-11, LG-12, LG-13) and `## ADDED Requirements` (LG-21 sink dispatch isolation, LG-22 BufferedSink no-deadlock, LG-23 MultiSink fan-out, LG-24 generic Logger, LG-25 concrete loggers, LG-26 lifecycle controls, LG-27 Sensitive<T> envelope).
- [x] 1.2 Add `**Verified by:**` line to every existing LG-NN requirement in the folded spec on fold.

## 2. Implementation

- [x] 2.1 Add `fallbackSink?: Sink` to `AbstractLoggerConfig`; default to a sink that writes failure records via `console.error`.
- [x] 2.2 Replace `dispatchToSinks` body with per-sink try/catch that emits `LoggerError(LOGGER.SINK)` to `fallbackSink`, increments `droppedBySinkError`, fires `logger.dropped_total{reason:"sink_error"}`, and continues to remaining sinks.
- [x] 2.3 Add `droppedBySinkError: number` to `LoggerMetrics` and initialise in `freshMetrics`.
- [x] 2.4 Replace `BufferedSink` block-policy waiter list with inline-drain on overflow; throw `LoggerError(LOGGER.CONFIG)` on non-positive `maxQueueSize`.
- [x] 2.5 Update affected unit / conformance tests.

## 3. Conformance test

- [x] 3.1 Add `packages/observability/logger/src/conformance.spec-conformance.test.ts` pinning:
  - sink throw is captured into `fallbackSink` with code `LOGGER.SINK` and increments `droppedBySinkError`;
  - sink rejection is captured into `fallbackSink` and increments `droppedBySinkError`;
  - the second sink in a list still receives the record when the first throws (per-sink isolation);
  - `BufferedSink({ overflowPolicy: "block", maxQueueSize: 1 })` makes forward progress without an external `flush()`;
  - `BufferedSink({ maxQueueSize: 0 })` throws `LoggerError(LOGGER.CONFIG)` at construction;
  - `MultiSink([a,b])` writes to both `a` and `b` in parallel.

## 4. Gate

- [ ] 4.1 `bunx turbo lint typecheck test --filter=@suaveplan/logger` green.
- [ ] 4.2 `bunx turbo test:coverage --filter=@suaveplan/logger` 100/100/100/100.
- [ ] 4.3 `bun scripts/openspec-conformance.ts @suaveplan/logger` exits 0.

## 5. Fold + archive

- [ ] 5.1 Fold delta into `openspec/specs/logging/spec.md`.
- [ ] 5.2 Move `openspec/changes/logger-silent-failure-fix/` to `openspec/archive/2026-04-27-logger-silent-failure-fix/`.