[poteto]

The statechart test "a SIGKILL of the command while the view draws the chart leaves no folder behind" fails on macOS. This PR makes assertGone wait for the reap. It changes only cli.test.ts in pstack/ and in its harness/pstack/claude-code/ copy.

Cause

When the command gets SIGKILL, the janitor kills the process group of the worker, and launchd reaps the orphaned worker. On macOS, kill(-pgid, 0) returns EPERM while the group holds only zombies. It returns ESRCH only after the reap. assertGone took the first error as final and expected ESRCH.

Fix

assertGone keeps polling through EPERM until it gets ESRCH, in the same budget of 250 x 20 ms. Any other error still fails at once. The timeout message now says whether the process is still running or exited but was not reaped.

Measurements (on a Mac)

• Before, on main: 39 of 40 runs failed at normal load. 35 of 40 runs failed with 32 extra busy processes. Every failure was EPERM !== ESRCH.
• After: 100 of 100 runs passed at normal load. 100 of 100 runs passed under load (load average up to 96). Across 80 instrumented runs, the EPERM state lasted 22 ms or less.
• Mutation check: when the janitor does not kill the worker, the fixed test still fails after about 6 s with "is still running". The fix does not hide a worker that survives.
• Full CI command: 263 pass, 0 fail, 66 skip. Before: 262 pass, 1 fail.