89 lines of grep/sed pipeline become a service returning a FactIdCheck and a
router that renders it. Parity on the live tree is exact: both implementations
print "check-fact-ids: OK — 6 references validated against 61 canonical facts"
and exit 0. The matching counts are the real evidence — a line-matching regex
that differed from the grep chain even slightly would move 6 or 61.
Kept line-matched rather than YAML-parsed on purpose. Parsing properly would
change which lines count: anchors, merge keys and multi-document files would
start contributing ids the old check never saw. That is a different check
wearing the same name, and a port is not the place to make it.
Three parity cases: ok, unknown fact_id, and the advisory mode where the
catalogs hold no definitions and the gate deliberately exits 0 — failing every
commit until they are populated would teach people to bypass the hook, and a
gate people route around protects nothing.
Proven to fail by removing the entity-attributes.yaml exclusion, and caught in
a way worth noting: not by the assertion aimed at it, but by the advisory case,
where including that file made the catalog non-empty so the new implementation
enforced while the old stayed advisory. A real behavioural divergence, surfaced
by exit code.
Retirement waits for the whole domain, per the per-domain rule — three gates
remain. It also resolves a tension: the parity test copies the old script into
its fixture, so deleting the script early would delete the test's own subject.
A parity test is scaffolding with a defined lifetime.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 5
b88791705c