The rationale-edit exemption was a substring test over the whole commit range, so any
message containing the literal marker armed it -- including prose explaining why no
marker was needed, which is how it fired live in PR #605: a green --base/--head run
that was vacuous on the body-diff dimension, in the one PR that hand-resolved a merge
conflict inside the corpus the guard exists to police.
Now read as an affirmative `Decisions-Edit:` git trailer. Git parses trailers only in
the final paragraph, so a quoted example message cannot arm it -- which matters because
this commit and its decision record both quote one. A non-affirmative value (`no`) does
not arm it either; the retired substring arms nothing and gets a ::warning:: nudge.
Tests: negative controls (prose mention, quoted mid-body trailer, `no` value, retired
substring) plus positive controls (trailer, uppercase, alongside Co-Authored-By). All
four negative controls verified red against the old matcher.
fixes#609
Decisions-Edit: yes
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>