tests: a live-process helper outlives an interrupted test run #693

Found on a macOS host on 2026-10-24: 93 orphaned bun --eval setInterval(() => {}, 1000) processes, re-parented to pid 1, started over five days. That command is the live-process helper several tests spawn (mail-lock-pid-state, launch-snapshot-sweep-667, pid-state-callers-677, real-flair-lane). The tests stop their helpers in teardown, so a run that is interrupted (a killed test process, a timed-out lane) leaves them running.

What the fix does

The shared live-process helper exits on its own when the test process that started it goes away (for example it watches its parent: stdin closed, or process.ppid changed), so an interrupted run cannot leave it behind. All the tests that spawn one use the shared helper. Test: start the helper from a short-lived parent, kill the parent, and assert the helper has exited within a bound.