Round three found the one half of the new mechanism with no relevance gate.
`verify_claim`'s GREEN path read exactly two things — the run exited 0, and
something PASSED — and both are satisfied by a proof that never touches the
mutated file at all. Reproduced before fixing: retargeting the shipped GREEN
entry's proof from `test_check_doc_narrative.py` to `test_bom_guard_detection.py`
changed nothing, and the entry still reported verified. The RED direction never
had this hole, because a proof that ignores the mutation stays green and is
refused as "the clause is not load-bearing".
So a GREEN entry now declares a `reach_replacement` and its `reach_expect`: a
SECOND mutation of the SAME clause, required to REDDEN the same proof, executed
through `verify_mutation` so its red is read through the diagnostic gate rather
than on exit status. The shipped entry declares `path = p` — dropping the `b/`
stripping every scanned diff header goes through — and the run then scans
NOTHING, which is what the declared diagnostic reads. The same retarget now
fails, naming the reach verdict.
The gate runs LAST of the three: run first it would refuse before the status and
vacuity gates were read and neither could be witnessed failing alone (#685), and
the sandbox is reset between a claim's two proof runs for the reason it is reset
between mutations. It has its own disarm proof, and the two synthetic claim
sandboxes are now real git repositories so `reset_sandbox` has a baseline;
`_lib_with` shares the baseline registry, since a copied module's own starts
empty.
Also from that round:
- The record no longer counts the mutation-outcome claims in the pinned
proposal-3 scan. A third of the same shape sits in the same result set
(`test_a_verdict_BEYOND_A_SHORT_PAGE_is_still_found`), and which side of the
line a sentence falls on is a judgement, so an exact count is a figure the
next reader re-derives differently — the failure this record is about.
- The calibration paragraph no longer restates the post-review-verdict outcome
as a dated witnessing. It points at the `CLAIMS` entry that executes it, which
is the form the rewritten shell comment beside it demands.
- The comment in `check-doc-narrative.py` claimed a universal ("reddens no
test") while one file is executed. It now names that file, so the quote binds
an outcome no wider than what is checked.
- Proposal 4 from the issue is dispositioned explicitly: rejected as a rule
here, on the issue's own argument that an exhortation does not fire at the
moment of least slack.
- `docs/README.md`'s task-signal parenthetical now names the `CLAIMS`
population; the file was owned by another slot when this branch started.
Cost re-measured 2026-09-05, three baseline/branch pairs: the `CLAIMS` half adds
31.7-43.6%, up from the 12.7-16.6% measured before the gate existed. The old
figure is retired rather than scaled — growing the population invalidates the
measurement that described it.
Refs #881
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015QqCpYFsKgnAnx6jVwrKiV
timothyandClaude Fable 5.1
a9341d8415