claude-code - 💡(How to fix) Fix Foreground Bash/TaskStop don't kill subprocesses; harness tracks ghost shells [1 participants]

Summary

In a single 40-minute session, three different harness paths left processes running after they should have been dead, and the UI kept reporting activity for work that had long finished. The result was ~35 minutes of wasted wall time plus orphan processes holding container / DB resources.

Repros

1. task test -- --filter=X hangs silently for 30+ min with zero feedback

The task wrapper (our project's taskfile) eventually invokes php artisan test which passes --no-output to Pest. With coverage-mode Xdebug enabled, Pest can stall at ~0% CPU while the UI shows a running Bash call producing zero output. No way to tell from the UI whether the call is working, hung, or deadlocked.

Expected: either periodic heartbeat output from the harness, or a timeout warning when a Bash call goes quiet for N minutes.

2. TaskStop removes the task from the harness but leaves the OS process alive

I called TaskStop on a task test:parallel shell. Harness reported "Successfully stopped task". `ps` showed the PHP / pest processes still running 28 minutes later at 0% CPU — they weren't sent SIGTERM/SIGKILL.

Expected: TaskStop should propagate the signal to the process group (setpgrp + killpg), or at least warn "process still alive after stop signal".

3. Rejecting a Bash tool call doesn't kill the subprocess it already started

I hit "reject" on a foreground `docker exec … pest …` call about 10 seconds after it started. Four minutes later the pest invocation was still running inside the container. I had to manually `kill -9` the host-side `sh` wrapper.

Expected: user-side rejection should trigger SIGKILL of the spawned subprocess tree, not just disconnect the harness's read handle.

4. UI "N shell still running" banner is stale

After (1) / (2) / (3) were manually reaped via `kill -9`, the UI kept displaying "1 shell still running" for the remainder of the session. No way to clear it without starting fresh tool work.

Impact

• ~35 minutes of wasted wall time in one session.
• Resource leak: orphan PHP / docker processes holding DB connections + container memory.
• Status indicators can't be trusted — had to shell out to `ps` / `docker exec` repeatedly to know the real state, which defeats the purpose of an agentic harness.

Environment

• Claude Code CLI
• Model: Opus 4.7 (1M context)
• OS: Fedora 43, Linux 6.19.12
• Tools involved: Bash (foreground), TaskStop, Monitor

Suggested fixes

• Spawn subprocesses in their own process group; on rejection / TaskStop / session end, `killpg(-PID, SIGKILL)`.
• Emit a "no output for Nm" notification so silent hangs are visible without polling `ps`.
• Reconcile the "shells running" counter against real PIDs at each tool call; auto-clear ghosts.