Test shards 3 and 4 were silently failing on every open PR because vitest's
CLI parser was treating `--shard X/Y` as positional file filters whenever the
arg arrived after a `--` separator. Removing the `--` in ci-test-shard.mjs
restores per-shard slicing; verified locally that shard 1/4 and 2/4 now run
distinct subsets.
The two consistently-failing engine tests:
1. self-healing in-review-branch-rebind ambiguous case-variant detection:
dedup keyed on lowercase branch name collapsed two physically distinct
refs (allowed on Linux ext4) into one candidate, so the "applied" path
ran instead of "ambiguous-candidates". Dedup now keys on the resolved
SHA — macOS APFS still collapses (same ref, same SHA), Linux keeps both
(distinct SHAs) and the ambiguity skip path fires as designed.
2. worktree-acquisition resume-misbinding spy: the production
verifyResumeBranchNotMisbound returns early when `git merge-base HEAD main`
fails, which is exactly what happens on shallow checkouts. Bumping the
test-shards checkout to fetch-depth: 0 makes CI mirror the local git
state these engine tests rely on.
Also adds `push: branches: [main]` to PR Checks so regressions like this
(which slipped into v0.33.0 with no post-merge run) go red immediately
on landing instead of being discovered on the next PR.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>