The non-negotiable from D-263, pointed at its worst hiding place: a foreground
command that swallows a failure at least does it in front of someone, while a
background runner that reports "started" and loses the failure does it where
nothing is watching.
Testing the two timing cases the ticket names — fails before the parent exits,
fails long after — needs a command slow enough to tell them apart, and every
verb in reach finishes in milliseconds. So `reach dev selftest` exists: emits
progress for N seconds, then optionally fails with a chosen code. A genuine
diagnostic rather than a test hook, in the dev domain the map already planned,
and the only way to answer "does streaming work here, can I tail it, does a
failure survive detach" by observation instead of argument.
The slow case is the one that proves the design. --detach returned in 75ms
while the child ran six seconds, so the parent was demonstrably gone long
before the child failed — and wait still relayed exit 7. That is the half of
the recording path only this case reaches, and why T-1277 moved completion
recording into the child.
Also pinned: --detach exits 0 for starting and SAYS "not succeeded" in words,
which the test asserts on rather than trusting the code to be read correctly;
a failed job nobody waited on shows as failed in jobs list; and every event a
detached job emits carries its job id.
Closed T-1278's open gap in passing — jobs log --follow had never run against a
genuinely long job because none existed. It now has: attached mid-flight,
streamed the remaining steps live, and caught the final verdict after the job
ended.
Proven to fail by making effective_exit_code always return 0 — the trap itself.
Both timing cases failed by name.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>