Four red CI incidents across #213 and #214 were each judged "not caused
by this PR", and #214's case is airtight: it is docs-only and its tree is
byte-identical to a green main. THAT PROVES THE PRs DID NOT CAUSE THEM.
It does not prove they are harmless environmental noise, and three of the
four have a specific, findable mechanism. This lane separates those two
claims, which the current process conflates.
FOUR INCIDENTS, THREE TESTS, FOUR SIGNATURES. The registry counts
signatures, not test names, because the process test alone produced two
with different mechanisms and different causal status — collapsing them
under one name is how a possible product defect acquires a flake's
immunity.
1. supersede_cancels_in_flight_job_within_50ms —
"supersede did not cancel within 50ms". MEASUREMENT DESIGN. Its
premise is a 15ms sleep asserted-by-comment to mean "the worker
picked the job up"; on a loaded runner it may not have, in which
case the test measures the QUEUED path while claiming the running
one. And the 50ms clock starts before the second dispatch and is
consumed by the test's own tick+sleep pump, so the measured
interval is dominated by when THE TEST got scheduled. Widening the
number would make it pass and measure nothing more.
2. a_successful_signal_disposition — "leader=exited(signal SIGUSR1)".
TEST RACE. Readiness is ProcessEventKind::Started, emitted at
SPAWN, not when /bin/sh has installed `trap '' USR1`. USR1's
default disposition is terminate, so a signal in that window kills
the child. The fixture's own comment states the requirement it does
not enforce.
3. a_successful_signal_disposition — "EPERM,
measured_group=unobservable(ESRCH), leader=live". NOT a test race:
the group-target behaviour #176 and #200 circled and the
reap-ledger lane parked disposition changes pending. Recorded
UNRESOLVED, POSSIBLE PRODUCT DEFECT, with a diagnosis — never a
green rerun — as its retirement condition.
4. terminal_escape_gates — "left: [], right: [49]". TEST RACE.
`wait_for_file` returns as soon as `fs::read` succeeds, which
succeeds on a ZERO-BYTE file; the probe's `open()` creates the file
before `write()` fills it. The predicate is "readable", the
assertion is "contains 1" — the same shape as signature 2, fixable
at the helper so every caller inherits it.
THE EXISTING PROSE IS DUPLICATED AND KEYED BY NAME. Flake claims live in
at least six places, disagree in detail, carry no signatures or evidence
links, and the handoff's list names three tests — two of which are not
among these four incidents, while three of the four are absent from it.
A list that is both stale and incomplete is worse than none: it confers
"known flaky" on whatever happens to be named and withholds it from
everything else. Acceptance 3 therefore AUDITS the existing three: each
is carried in with a signature and evidence, or removed with a note. No
entry survives on reputation.
The rerun rule is REPLACED rather than softened: one rerun reproducing
the SAME signature is evidence of intermittence only; a DIFFERENT
signature, or the same one twice consecutively, requires investigation
or a merge-base control before the red is attributed to the environment.
Quarantine, if hardening fails, is a separate STILL-BLOCKING CI step —
never #[ignore], continue-on-error, or silent retry-to-green. A
quarantine that stops failing the build is a deletion with extra steps.
Framing only. Sequencing is registry first, hardening second, per
review.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Levi Neuwirth
d6bf0c3233