Dead-PID and zombie job reconciliation

[JohnnyVicious]

Summary

When a tracked job's worker process dies between SessionStart and SessionEnd (crash, OOM, SIGKILL, parent detached), the job record stays status: "running" for the rest of the session. buildStatusSnapshot and enrichJob in plugins/opencode/scripts/lib/job-control.mjs never probe process.kill(pid, 0) — they only read the stored status field.

Cleanup today only happens in plugins/opencode/scripts/session-lifecycle-hook.mjs:27-44, which runs on SessionEnd. During the session itself, /opencode:status and /opencode:result can display rows whose PIDs are long dead.

Repro

1. Start a background task via /opencode:rescue --background.
2. kill -9 the background worker PID.
3. /opencode:status still shows the job as running.

Suggested fix

In enrichJob (or buildStatusSnapshot), for any job.status === "running" with a job.pid, probe with process.kill(pid, 0). On ESRCH, downgrade to failed + errorMessage: "Worker process exited without updating job status." and persist via upsertJob.

Upstream reference

Derived from openai/codex-plugin-cc#164.

[JohnnyVicious]

Consolidating zombie-job follow-ups here: #15 covers stale running rows accumulating in state, and #42 covers the reference implementation for reconciling dead PIDs during status reads. This issue is now the canonical tracker for dead-PID detection plus zombie state cleanup.

[JohnnyVicious]

Dead-PID reconciliation implemented in PR #51 commit a4e0097 (isProcessAlive probe + markDeadPidJobFailed + reconcileIfDead wired into buildStatusSnapshot/handleResult/handleCancel). Issue was a parent tracking stub; implementation is done.