P0 — parsePorcelainZ rename/copy handling
Git's -z porcelain emits `R <new>\0<old>\0` for renames (and
C for copies). The naive split-and-slice treated <old> as an
independent dirty path, which made runObservedDestructiveSyncOp
warn about phantom "cleared paths" whenever a rename was in
flight. Now we detect R/C status and skip the trailing entry.
P1 — race-rescue loop unstages between attempts
`git stash create` snapshots the index without clearing it, so
iteration 2's `git add -A` would re-stage atop iteration 1's
leftovers. Tree differences inside the loop then reflected stale
staging rather than genuine new writes. Added a `git reset` at
the top of each iteration so every attempt starts from a clean
index baseline.
P1 — writeActiveMergerStatus is now atomic
Switched from in-place writeFileSync to temp-file + renameSync.
POSIX guarantees rename atomicity on the same filesystem, so a
reader can no longer catch the file mid-flush and return a
false-negative "no merger active" advisory.
P2 — Step regex em-dash clarity
`[—\-:]` is functionally fine but obscures intent; switched to
`(?:—|-|:)` so the em-dash branch is obvious. Added a test case
for the em-dash separator.
New tests:
- parse-porcelain-z.test.ts (8 cases including renames + copies)
- em-dash case added to derive-subject-summary.test.ts
247/247 merger-suite tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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