Background Task Watchdog

Background/long jobs can (1) loop forever, or (2) finish but never fire the
completion notification. Relying only on the notification can leave you stuck.
Always watch them on a time bound.

Procedure

1. Estimate & record. Before launching, note what "done" looks like (a
   terminal success line in the output) and a rough max expected duration
   (e.g. npm i ~1–2 min, download depends on size, a check ~30–60s).

2. Launch, then set a checkpoint — don't wait blindly. After starting the
   job, plan an explicit check at ~the expected duration instead of assuming
   the notification will arrive. Pick the lightest mechanism:

   • Re-read the job's output file (tail/Read) to see current progress.
   • If the harness may not wake you, use ScheduleWakeup (fallback tick,
     1200s+ for idle; shorter only when actively polling external state) or a
     Monitor until-loop to poll a concrete condition.

3. On checkpoint, classify:

   • Terminal success line present → done, proceed (verify the result, don't
     just trust exit code).
   • Still running, output advancing → fine, extend the checkpoint.
   • Still running, output unchanged past max expected / spinner forever →
     treat as hung / infinite loop. Inspect (last output lines, is the
     process alive?), then stop it: TaskStop for a tracked job, or kill the
     PID. Diagnose root cause before retrying — never relaunch into the same
     hang.
   • Process gone but no notification fired → read the output file to get
     the real result; continue from there.

4. Never claim completion from a background job without reading its output.
   A completion notification (or exit 0) is not proof — confirm the expected
   terminal line / artifact actually exists.

Notes

• Prefer run_in_background for genuinely long ops, but pair it with a
  time-bound check per above.
• Avoid foreground sleep loops to wait; use Monitor/ScheduleWakeup.
• On Windows, watch for commands that prompt (UAC, interactive) — they can
  appear to "hang" while silently waiting for input; those must be run by the
  user or made non-interactive.