Files
PaperClipAI/tests
DottaandClaude Opus 5.5 a434edf991 fix(runner-e2e): treat macOS EPERM from a zombie-only process group as exited (#19470)
## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - The runner E2E suite restarts the Paperclip server to prove that
agent work recovers after a controller restart
> - The restart supervisor in `tests/runner-e2e` owns the server process
tree and escalates to SIGKILL when graceful stop takes too long
> - On macOS, `kill(-pgid)` returns EPERM, not ESRCH, when every member
of the group has exited but is not reaped yet
> - The supervisor treated that EPERM as fatal, so a server that exited
at the same moment as the SIGKILL escalation aborted the restart with
"Owned tree cleanup incomplete: Error: kill EPERM"
> - This pull request makes the supervisor re-inspect the process table
on EPERM and skip the group only when no running member remains
> - The benefit is that restart recovery cases no longer fail on a
harmless exit race on macOS, while a real permission failure still fails
cleanup

## Linked Issues or Issue Description

No public issue exists. This describes the bug.

**What happened?**
The runner E2E cell
`everyday-workflows.runner-codex.local.recover-controller` failed on
macOS with failure class `cleanup_failure`: "Stopped waiting for
isolated server restart ...: Owned tree cleanup incomplete: Error: kill
EPERM". The server log shows that the graceful stop took 30 seconds, the
supervisor sent SIGKILL, and the server exited with code 0 in the same
instant. The restart did not start, so the case never checked recovery.

**Steps to reproduce**
1. On macOS, fork a child that calls `setpgid(0, 0)` and exits. Do not
reap it.
2. Call `killpg(child, SIGKILL)`. The kernel returns EPERM (errno 1),
not ESRCH. After the reap, it returns ESRCH.
3. In the runner E2E supervisor, any group that becomes zombie-only
between the `ps` inspection and the signal causes the same EPERM, which
the code rethrows.

**Expected behavior**
A group whose members have all exited counts as stopped, the same as
ESRCH. EPERM stays fatal while a running member remains.

**Environment**
macOS 26.5 (Darwin 25.5.0), arm64, Node 26.4. The behavior is the same
with and without the Claude Code sandbox.

## What Changed

- `tests/runner-e2e/process-tree-owner.ts`: on EPERM from a group
signal, read a fresh process table. Skip the group (as with ESRCH) only
when it has no running (non-zombie) member. Otherwise rethrow.
`signalSnapshot` is now async.
- `tests/runner-e2e/process-tree-owner.test.ts`: two regressions. One
covers a group that becomes zombie-only when signaled. One proves that
EPERM stays fatal while a running member remains.
- `tests/runner-e2e/README.md`: document the EPERM rule next to the
existing zombie rule.

## Verification

- Red before the fix: `node node_modules/vitest/vitest.mjs run --config
tests/runner-e2e/vitest.config.ts
tests/runner-e2e/process-tree-owner.test.ts` failed with `promise
rejected "Error: kill EPERM"`.
- Green after the fix: `process-tree-owner.test.ts`,
`server-stop.test.ts`, and `process-tree.test.ts` pass (35 tests). `pnpm
test:e2e:runner:typecheck` passes.
- Kernel behavior: a Python fork probe on this Mac shows that `killpg`
on an unreaped zombie group returns EPERM, both inside and outside the
sandbox.
- Live cell: `pnpm test:e2e:runner -- --max-automatic-retries 0 --id
everyday-workflows.runner-codex.local.recover-controller` on macOS. The
fixed revision passed. The server stop escalated to SIGKILL, the
replacement server started, and the run recovered. See the comment below
for the second rerun.

## Risks

- Low risk. The change is in the test harness only.
- EPERM is ignored only after a fresh inspection shows that no running
process holds that group ID. A process group ID cannot be reused while
zombie members still hold it, so the supervisor does not signal or skip
an unrelated group.
- The extra `ps` read runs only on EPERM.

## Model Used

- Claude Opus 5.5 (`claude-opus-5-5`), Anthropic, via Claude Code with
tool use (shell, file edits). Default context window.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-11-06 09:48:52 -06:00
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