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).

2 files changed, 13 insertions, 12 deletions

diff --git a/packages/host-bin/package.json b/packages/host-bin/package.json
index 12ae633..a3e24c8 100644
--- a/packages/host-bin/package.json
+++ b/packages/host-bin/package.json
@@ -11,6 +11,7 @@
 		"@dispatch/provider-openai-compat": "workspace:*",
 		"@dispatch/session-orchestrator": "workspace:*",
 		"@dispatch/transport-http": "workspace:*",
-		"@dispatch/tool-read-file": "workspace:*"
+		"@dispatch/tool-read-file": "workspace:*",
+		"@dispatch/journal-sink": "workspace:*"
 	}
 }
diff --git a/packages/host-bin/src/main.ts b/packages/host-bin/src/main.ts
index 0cb0d37..0c795b8 100644
--- a/packages/host-bin/src/main.ts
+++ b/packages/host-bin/src/main.ts
@@ -2,14 +2,16 @@ import { mkdirSync } from "node:fs";
 import { dirname } from "node:path";
 import { extension as authApikeyExt } from "@dispatch/auth-apikey";
 import { extension as conversationStoreExt } from "@dispatch/conversation-store";
+import { createJournalSink } from "@dispatch/journal-sink";
 import {
 	type ConfigAccess,
 	createBus,
 	createHost,
+	createLogger,
 	type EventsEmitter,
 	type Extension,
 	type HostDeps,
-	type Logger,
+	type LogDeps,
 	type PermissionGate,
 	type ScheduledJob,
 	type SecretsAccess,
@@ -22,15 +24,6 @@ import { extension as toolReadFileExt } from "@dispatch/tool-read-file";
 import { createServer, extension as transportHttpExt } from "@dispatch/transport-http";
 import { configMapToAccess, envToConfigMap } from "./config.js";
 
-function createConsoleLogger(): Logger {
-	return {
-		debug: (message: string, ...args: unknown[]) => console.debug(`[debug] ${message}`, ...args),
-		info: (message: string, ...args: unknown[]) => console.info(`[info] ${message}`, ...args),
-		warn: (message: string, ...args: unknown[]) => console.warn(`[warn] ${message}`, ...args),
-		error: (message: string, ...args: unknown[]) => console.error(`[error] ${message}`, ...args),
-	};
-}
-
 function createEmptySecrets(): SecretsAccess {
 	return {
 		get: async () => null,
@@ -64,7 +57,11 @@ const CORE_EXTENSIONS: readonly Extension[] = [
 ];
 
 async function boot(): Promise<void> {
-	const logger = createConsoleLogger();
+	const journalPath = process.env.DISPATCH_JOURNAL ?? "./.dispatch/journal/app.ndjson";
+	mkdirSync(dirname(journalPath), { recursive: true });
+	const logSink = createJournalSink({ path: journalPath });
+	const logDeps: LogDeps = { now: () => Date.now(), newId: () => crypto.randomUUID() };
+	const logger = createLogger({ extensionId: "host-bin" }, logSink, logDeps);
 
 	const dbPath = process.env.DISPATCH_DB ?? "./.dispatch-data/dispatch.db";
 	mkdirSync(dirname(dbPath), { recursive: true });
@@ -83,6 +80,8 @@ async function boot(): Promise<void> {
 		scheduler: createNoopScheduler(),
 		bus: createBus(logger),
 		events: createNoopEvents(),
+		logSink,
+		logDeps,
 	};
 
 	const host = createHost(CORE_EXTENSIONS, deps);
@@ -102,6 +101,7 @@ async function boot(): Promise<void> {
 	const port = Number(process.env.BACKEND_PORT) || Number(process.env.PORT) || 24203;
 	const server = Bun.serve({ fetch: app.fetch, port });
 	logger.info(`Dispatch listening on http://localhost:${server.port}`);
+	console.info(`Dispatch listening on http://localhost:${server.port}`);
 }
 
 boot().catch((err) => {