Uniqueness is a property of HEAD alone — no base ref, no merge base, no base
blob. It sat downstream of all three, so every degradation path returned
success on a tree carrying a duplicate.
The base-blob path was the worst: a branch that introduces CHANGELOG.md hit a
bare `exit 0` on a message that was true about deletion and silent about the
duplicate in front of it. STRICT could not reach it — STRICT guards the two
skip() calls, and that is not one of them.
That inverted the two halves. Deletion needs a diff to see; duplication is the
one changelog_section() actually mis-renders, stopping at the second heading
and truncating the release's real body. The half with the live extraction bug
behind it had the most ways to silently not run.
Moved, not rewritten. The skip messages now say containment skipped and that
uniqueness already passed. The CI step is no longer pull_request-only, with a
`github.ref_name` fallback because base_ref is empty on a push and a bare
`origin/` under STRICT would redden every push to main. The script is also now
100755, matching cast's copy of the same file.
Regression cases pin the ORDER, not the exit code: verified they go red
against the pre-fix script (7 failures) and green against the fixed one.
Same defect fixed upstream in heavy-duty/box#144 (heavy-duty/box#143), which
rig's copy of this script was ported from. Found by claude-bot-andresmgsl and
codex-bot-andresmgsl reviewing #99.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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