feat(daemon): auto-respawn via per-project watchdog (#116) - #119
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When the shared MCP daemon is killed (Stop-Process, kill -9, crash) while the proxy host is still running, the incremental file-watcher was lost until the user manually ran 'codegraph-vba sync'. This change adds a per-project daemon liveness watchdog inside the proxy that polls the daemon's .codegraph-vba/daemon.pid lockfile every 30s and respawns the daemon (via the same detached-spawn recipe the launcher uses) when the pid points at a dead process.
Architecture:
- src/mcp/daemon-watchdog.ts (new): DaemonWatchdog class. Constructor takes an injectable spawnFn so tests can stub the detached spawn without ESM-fragile vi.mock('child_process') patches. hasLiveDaemon(root) reads the lockfile via decodeLockInfo (the lockfile is the authoritative pointer; listDaemons filters dead entries from its return value, so it cannot be used to detect a dead daemon -- that was the trap in v1).
- src/mcp/index.ts: MCPServer (proxy mode) instantiates a watchdog per project root, starts it, and tears it down on stop(). Watchdog intervals are unref-ed so they never keep the proxy alive.
Why a watchdog (vs. spawn-on-demand at MCP request time): the issue's repro is Stop-Process -Id <pid> while the MCP keeps serving -- file edits are missed until the user manually runs 'codegraph-vba sync'. The watchdog closes that gap in <30s.
Tests (15/15 green across the daemon tests):
- __tests__/daemon-watchdog.test.ts (9 tests): covers hasLiveDaemon for the 3 lockfile states, checkAndRespawn (live=no-op, dead=respawn, no-.codegraph=no-op), tick -> respawn integration (single + double), start/stop behavior.
- __tests__/daemon-registry.test.ts: unchanged, still 6/6.
Closes #116.
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Summary
The shared MCP daemon auto-respawns when killed while the proxy is still up. After \Stop-Process -Id \ (or any other death cause) the proxy per-project daemon watchdog detects the dead daemon via its .codegraph-vba/daemon.pid\ lockfile and respawns it within 30s — file edits are picked up automatically instead of needing a manual \codegraph-vba sync.
What is in
Acceptance
px vitest run tests/daemon-watchdog.test.ts\ — 9/9 passed
px vitest run tests/daemon-registry.test.ts\ — 6/6 (no regression)
px tsc --noEmit\ clean
Reopens the work from #118 after a rebase to resolve the CHANGELOG conflict with #117. Closes #116.