Stage 2 of `docs/macos-ci-signal-integrity-framing.md` revision 3
(acceptance 6–9). Two test races, both the same shape: the thing waited
for was weaker than the thing asserted, so the wait could return inside
the window the assertion needs closed.
R4 — `wait_for_file` returned as soon as `fs::read` succeeded, which
succeeds on a ZERO-BYTE FILE. The probe publishes with
`open(path,'wb').write(b'1')` and `open()` creates the file before
`write()` fills it, so the helper handed `[]` to a caller asserting
`== b"1"`. It now takes the expected bytes and waits while the file
holds a STRICT PREFIX of them — the states a write in flight can be
observed in — returning anything else immediately so the caller's
`assert_eq!` stays the discriminating assertion rather than becoming a
timeout inside a helper that does not know what was expected.
All four callers pass their expectation. `wait_for_published_file`, one
function away in the same suite, gated the real-TUI smoke's
`assert_eq!(…, b"1")` on the identical predicate and is fixed with it:
leaving it would have let R4 recur under a different selector, which the
registry would then have had to judge a new incident.
R2 — the USR1 fixture waited on `ProcessEventKind::Started`, emitted at
SPAWN, not when `/bin/sh` has parsed `trap '' USR1`. SIGUSR1's default
disposition is terminate, so a signal inside that window kills the
child. The child now publishes a marker AFTER the trap and the test
waits for that marker's CONTENT (the same zero-byte trap applies to a
shell's `>` redirection). `exec` replaces the forked `sleep`, so the
group holds exactly one process and the ignored disposition survives by
POSIX rather than by the shell's fork-suppression optimization — an
unstated dependency the old fixture had, since these signals are
group-directed and a forked `sleep` is an untrapped group member.
Four witnesses, each verified by REVERTING the fix and observing the
failure rather than by reasoning about it:
- `wait_for_file_does_not_return_a_zero_byte_readiness_file` fails
`left: []`, `right: [49]` — R4's two required fragments, verbatim;
- `wait_for_file_does_not_return_a_partial_write` fails on the torn read
a length check alone would admit;
- `wait_for_file_returns_divergent_content_rather_than_timing_out` fails
against an over-strict helper that waits for an exact match;
- `usr1_readiness_waits_for_the_trap_not_for_the_spawn` fails
`left: Some("SIGUSR1")`, `right: Some("SIGTERM")` with the readiness
wait removed. Its fixture sleeps before `trap` so the pre-trap window
is deliberate rather than load-dependent, and it proves survival by
the child's EXIT DISPOSITION rather than by an absence observed within
a window.
R1 is NOT touched — referred to the async-runtime lane (Q#MCI3), because
widening its budget would make it pass and measure nothing more. R3 is
NOT touched and remains UNRESOLVED, owned by the process-signal /
reap-ledger lanes.
`docs/ci-red-signatures.md` moves R2 and R4 to a "Retired rows" section
with their dispositions and adds the rule the file needed and lacked: a
red matching a retired row is a RECURRENCE that puts the retirement in
question, never a known flake. `docs/active-work.md` carries this lane
from its first commit rather than after review asks for it.
Repetition sets, not single runs: the two `--lib` process tests 15/15,
the whole `vterm_stage2_acceptance` suite 15/15 at default parallelism.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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