feat(observability): Phase A logging substrate — Logger/Span ABI + journal sink (250 tests)

Structured, agent-first logging captured durably to an append-only journal file.

Kernel (contracts/logging.ts): leveled/attributed Logger + Span, auto-scoped per extension (host stamps manifest.id, unspoofable), incremental span records (open/close) for crash-reconstructable traces, injected LogSink (pure record-builder). ctx.log on ToolContract; runTurn opens turn/step/tool-call spans and captures the verbatim pre-mutation prompt (the 'before') on the step span.

journal-sink (new package, bootstrap dep — not an extension): LogSink appending NDJSON to a rotating journal; pure serialize + thin fs edge; fail-safe drop, never blocks a turn. host-bin injects it via HostDeps; session-orchestrator threads host.logger (childed per turn) into runTurn.

Redaction is per-extension self-redaction (no shared helper — isolation over DRY). The out-of-process collector + SQLite store + the verbatim 'after' provider.request capture are Phase B / next (notes/observability-design.md §10/§11).

Verified: tsc -b clean, 250 tests (218→+32), biome clean. Live boot: a turn's journal holds host logs + turn/step spans (open+close) + the prompt:before record with the verbatim messages array.

Harness: ORCHESTRATOR §3 rule-scoping map; .dispatch/rules/isolation-over-dry.md; notes/observability-design.md (design D1–D10 + Phase A/B plan).

1 files changed, 17 insertions, 3 deletions

diff --git a/packages/kernel/src/contracts/index.ts b/packages/kernel/src/contracts/index.ts
index 0b578cb..e4eba87 100644
--- a/packages/kernel/src/contracts/index.ts
+++ b/packages/kernel/src/contracts/index.ts
@@ -45,7 +45,6 @@ export type {
 	EventsEmitter,
 	Extension,
 	HostAPI,
-	Logger,
 	Manifest,
 	ManifestCapabilities,
 	ManifestContributions,
@@ -57,7 +56,6 @@ export type {
 	StorageNamespace,
 	TrustLevel,
 } from "./extension.js";
-
 export type {
 	EventHandler,
 	EventHookDescriptor,
@@ -66,9 +64,25 @@ export type {
 	HookDescriptor,
 	ServiceHandle,
 } from "./hooks.js";
-
 export { defineEventHook, defineFilter, defineService } from "./hooks.js";
 export type {
+	Attributes,
+	ErrorAttributes,
+	Level,
+	LogContext,
+	LogDeps,
+	Logger,
+	LogLineRecord,
+	LogRecord,
+	LogSink,
+	Span,
+	SpanCloseRecord,
+	SpanLink,
+	SpanOpenRecord,
+	SpanStatus,
+} from "./logging.js";
+export { createLogger } from "./logging.js";
+export type {
 	FinishEvent,
 	ProviderContract,
 	ProviderErrorEvent,