:Process makes sure no child outlives what it was started for. SIGKILL to
the direct child alone would leave the Playwright server and Chromium
running after a timeout, and every pass running after a SIGKILLed driver:
- every child is forked by one long-lived spawner thread, the reaper's
registry locked across fork, so PR_SET_PDEATHSIG holds and a fast exit
is never reaped unregistered; one reaper thread owns waitpid(-1);
- the child gets an empty signal mask, SIGPIPE and SIGXFSZ at their
defaults, and nothing but its three streams (close_range); the driver
ignores SIGPIPE and takes SIGINT/SIGTERM/SIGHUP on a thread of its own;
- `crafter-review __supervise <argv>` is a pass's subreaper. It kills the
pass's whole tree, Chromium's detached process group included, when the
target exits, on SIGTERM, and when the driver dies, by its death signal.
- Run() captures both outputs without the deadlock.
The shared state the detached threads wait on is never destroyed: a
condition variable destroyed under a waiter makes glibc's
pthread_cond_destroy, and with it exit(), wait forever.
:Platform: the Flatpak sandbox decided once, the host's XDG directories
restored there; WriteAtomic and LockedUpdate, the read-modify-write of
the board, ledger, memory.json and unit-state.json every driver on the
machine shares, under flock(2) on the same side files; /proc readers; and
the identity other drivers can check: natively pid and start time, in the
sandbox the instance's host pid from bwrapinfo.json with /proc/1's start
time. The lifetime lock is created under a temporary name and renamed into
place, so no prober ever finds it unlocked while its driver lives.
Tests: Process (the three ways a pass's tree must die, return codes, a
missing program, capture, timeouts, fds, the child's signal state),
Platform (atomic writes, LockedUpdate against a damaged file, two writers,
and another process holding flock on the side file; /proc on a fake
tree; both identities; the lifetime lock; the XDG restore).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
