§9 structured logging + OTLP observability (todo §9); structured, OTLP-native logging on @larvit/log (2.3.0, pinned; itself zero-dependency — the one new runtime dep). New pure src/logger.ts: createLogger() builds one app Log tagged service.name=plainpages (level/format/OTLP from config, injectable stdout/stderr); requestLogger() clones it per request (own root trace, inheriting level/format/streams/OTLP) into a "request" span, adopting an inbound W3C traceparent so a request continues an upstream proxy's distributed trace (malformed ⇒ fresh trace; clone honours a passed traceparent while dropping the parent's, unlike parentLog). app.ts builds the per-request log at the top of the handler and on res "close" (fires on completion AND abort, unlike "finish") emits one access line (method/path-without-query/status/ms/requestId, guarded) then end()s to flush the span (fire-and-forget .catch — a flaky collector never crashes a served request); the catch-all 500 + Ory-unreachable re-mint now log via reqLog.error/warn; static.ts mid-stream error takes an injected onError. server.ts builds the app logger, logs discovery/listen/shutdown, end()-flushes on SIGTERM/SIGINT (re-entry-guarded). bootstrap.ts events go structured (the human first-run banner stays raw). Config (environment-agnostic, fail-loud): LOG_LEVEL (info), LOG_FORMAT (text; prod compose → json), OTLP_ENDPOINT (unset ⇒ console-only; set ⇒ export logs + spans to an OTel Collector), OTLP_PROTOCOL (http/json|http/protobuf). compose: base sets LOG_FORMAT=json, dev override flips it to text. Tests-first: logger.test.ts (service.name/severity/level-gate/format, OTLP-only-when-endpoint, a stubbed-fetch proof it POSTs /v1/logs, requestLogger context-merge/own-root-trace/traceparent-continue/malformed-ignored), config.test.ts (4 toggles + validation), app.test.ts (live request emits the JSON access line), compose.test.ts (prod json / dev text). Stability-reviewer: APPROVE, no Critical/High (addressed both yellow nits — guarded access line + "finish"→"close" so aborted requests log; shutdown re-entry guard — and the green ones). README (config table, new Observability section, Status, Layout, runtime-deps) + AGENTS (deps) updated. typecheck + 326 units green (317 → 326).

src/compose.test.ts

@@ -67,6 +67,9 @@ test("prod base supplies the app secret via env and mounts no source; dev overri
   // Secret/cookie hardening: enforced in prod, off in dev so the throwaway + http cookies pass.
   assert.match(webBlock, /REQUIRE_SECURE_SECRETS:\s*"true"/, "base enforces real secrets");
   assert.match(override, /REQUIRE_SECURE_SECRETS:\s*"false"/, "dev allows the throwaway");
+  // §9 observability: prod emits structured JSON logs; dev flips it to human-readable text.
+  assert.match(webBlock, /LOG_FORMAT:\s*"json"/, "prod logs structured JSON");
+  assert.match(override, /LOG_FORMAT:\s*"text"/, "dev logs human-readable text");
   // Postgres credentials are env-supplied (dev default), never a baked-in literal.
   assert.match(compose, /POSTGRES_PASSWORD:\s*\$\{POSTGRES_PASSWORD\b/, "postgres password via env");
 });