The stat-cache seed (cp of the real index) stamped the temp index "now",
which defeats git's racy-git protection: an entry is only re-hashed when
its cached mtime is not older than the index file itself, so a same-size
rewrite landing in the same second as the last real index write looked
non-racy, kept its stale stat-cache entry, and vanished from the
fingerprint — evidence stayed FRESH after a source change. This is the
CI flake in test/evidence.test.ts "allow-paths carve-out" (sub-second
alignment on fast runners: expected STALE exit 1, got FRESH exit 0).
touch -r restores the original index timestamp, reinstating the exact
racy window git itself uses. Deterministic regression pin in
test/review-log.test.ts reproduces the miss with pinned zero-nsec
timestamps (fails on the old script, passes now); receipts: manual
probe shows the fresh-stamped copy returning the clean tree for a
same-size 'hello'→'howdy' rewrite while the mtime-carried copy detects
it.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
