Two defects in scripts/decisions_validate.py, fixed together because they share the
validator and its pytest suite.
#674 — the validator reported OK on frontmatter PyYAML rejects. The hand-rolled reader
is deliberately dependency-free (decisions-guard and the Husky hooks install nothing),
so it cannot see a bare apostrophe closing a single-quoted scalar. Hit twice in one
session by two independent agents. `pyyaml_frontmatter_faults()` now cross-checks the
parse against PyYAML whenever PyYAML is importable, and is SKIPPED with a ::notice::
when it is not — the read path stays dependency-free.
The two known hazards fail differently and the fix covers both: the apostrophe makes
PyYAML reject the document, while an unquoted ` #` parses fine and silently TRUNCATES
the value. So the check compares parsed results key by key rather than try/except-ing
the load, which is also what makes it generalize past the two known characters. PyYAML
wrote these files, so on disagreement it is authoritative and the file is the defect.
The comparison has one implementation, called by the validator and by the existing
test_decisions_lib agreement test, so the tool and the suite cannot drift.
#688 — test_real_corpus_ceiling_sits_at_the_TAIL_BOUNDARY asserted p90 <= 60 <= p95 in
the BLOCKING script-tests job. p90 sat exactly on the ceiling and the distribution above
it is sparse, so one ordinary record moved p90 by twenty lines and reddened CI for
whoever wrote it; it reproduced twice live (#672, #706) and both times the only in-scope
remedy was trimming the new record to fit the constant.
v5 splits the claim by robustness instead of hunting for a better single assertion. The
blocking test now asserts only the coarse, non-ratcheting property (the ceiling flags a
nonempty proper minority, 0 < fraction_over < 1/3); the fine tail-boundary claim is
measured every run and REPORTED as a ::notice::, on the same reasoning stale_records
already uses — a constant going out of date is the passage of corpus growth, not a
defect in the commit under test. The fine property is still asserted, against synthetic
distributions the test owns. The ceiling stays 60.
Verification: 424 scripts/tests pass; ruff at baseline parity (47 before and after);
the cross-check is clean on all 183 real records; a positive control pins that
record_wing_faults alone still reports both hazard files as clean, so the new red cannot
pass for the wrong reason; and a test demonstrates that appending #672's 62-line and
#687's 107-line records to the real corpus does not red the blocking property.
Docs: new record docs.frontmatter-pyyaml-crosscheck, docs.corpus-size-signal updated for
the v5 split, catalog regenerated, docs/ci-cd.md updated for both.
fixes#674fixes#688
Decisions-Edit: yes
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
timothyandClaude Opus 5
9d2b30dc3b