Codex review of the draft: the abort-on-dispose tests asserted only that
dispose() resolved and no warning fired — a regression back to untracked
fire-and-forget runs would pass both. The hook script now records its
shell PID before sleeping, and after dispose the test asserts
process.kill(pid, 0) throws: the drain resolves only after the killed
run settled (the child reaped), so ESRCH-by-dispose-return is
deterministic under the correct implementation, while an alive or
unreaped process fails it. Verified the discriminator by gutting drain()
locally: exactly these two tests fail.
a4152705ef