fix(pilot): restore agent registration + SSE directory scope

[iceglober]

Summary

Every pilot build since v0.16.x has stalled at exactly 5min with 0 events, last none. Diagnostic run revealed the real cause is not a timeout — it's two compounding bugs that both dropped every session-level SSE event before the bus saw it.

Bug 1: Pilot agents weren't registered in the spawned opencode server

opencode serve (spawned by the SDK's createOpencodeServer) does not load external plugins — only the interactive opencode TUI does. Verified: opencode serve --print-logs --log-level DEBUG shows zero service=plugin lines. So when the worker called promptAsync({ agent: "pilot-builder" }), the server accepted the request but no such agent was registered. The prompt silently no-opped; the session sat idle until the stall timer fired.

Fix: build a minimal Config containing only pilot-builder and pilot-planner (full permissions, prompts, model) and pass it via createOpencodeServer({ config }). The SDK forwards this via OPENCODE_CONFIG_CONTENT; opencode's config loader merges it with user config. Non-pilot agents (prime, qa-reviewer, etc.) stay out of the injection so user overrides remain in control.

Bug 2: EventBus subscription had no directory scope

opencode's /event SSE endpoint scopes message.updated, message.part.updated, session.idle, session.status, etc. by the subscriber's declared directory — exact match, not prefix. With no directory, the subscription received only server-wide events (server.heartbeat, server.connected, file.watcher.updated). Every session event the server published was silently discarded before the bus ever saw it.

Verified: 15s window over a live pilot-builder session with no directory → 2 events. With the session's exact directory → 27 events including session.idle.

Fix: EventBus constructor now takes a directory parameter and passes query: { directory } to client.event.subscribe. Because opencode's scope is exact-match (not prefix), a single bus scoped to a parent directory would still miss per-task events — so WorkerDeps.bus became WorkerDeps.busFactory: (directory: string) => EventBus. runOneTask creates a fresh bus per task scoped to the task's own worktree path, and closes it at teardown.

Secondary changes

• Default stallMs raised 5min → 60min. The old default was calibrated against the broken stream; with events actually flowing, legitimate inter-event gaps during deep subagent work (plan delegation, long tool chains, verify sub-runs) can exceed 5min. User-supplied stallMs still wins.
• scripts/diag-pilot.sh now uses bun instead of node to run the built CLI (the dist imports bun:sqlite).
• New PILOT_EVENT_LOG env var: when set to a writable path, EventBus dumps every raw SSE event (with extracted sessionID, live subscriber IDs, matched-subscriber count) as JSONL to that path. Zero overhead when unset; instrumental for the next debug of this kind.

Regression tests

• EventBus — directory scoping (3 new): lock the subscribe-call contract — when bus has a directory, query.directory MUST appear; when it doesn't, no query. Protects against a regression that would re-introduce the 5min stall.
• buildPilotServerConfig (4 new): locks the injected-agents contract — must include pilot-builder + pilot-planner with subagent mode and non-empty prompts; must NOT include other agents.
• Updated 11 existing pilot-worker.test.ts cases to pass busFactory instead of bus.

Full suite: 943 tests pass (was 936).

End-to-end verification

Re-ran the same rule-engine-refocus plan on kn-eng that had been stalling:

pilot build: run 01KQ5YF1FFVBGNP4KSHP12M6HD started (19 tasks)
[15:27:22] task.started T1-AUDIT-DOC
[15:28:54] task.verify.failed T1-AUDIT-DOC
[15:29:04] task.verify.failed T1-AUDIT-DOC
[15:29:09] task.stopped T1-AUDIT-DOC (builder STOP)
[15:29:09] task.started T3-RULE-ENTITIES

439 events captured (vs 38 heartbeats pre-fix). T3's session.jsonl = 209 lines of real agent activity. STOP protocol fires correctly on verify-fail. Zero stalls.

Changeset

.changeset/pilot-fix-sse-directory-and-agent-registration.md — patch bump.