Review

Review adversarially. Try to break the change and its chosen approach, ask whether a smaller change would do, and take the goal as given. Look hardest at compatibility, data loss, observability gaps, partial failure, races, security, stale state, unsafe retries or rollback, and violations of documented conventions.

If you wrote or changed the target in this session, hand this skill and the target to a fresh subagent and relay its report.

Don't comment on, approve, or request changes on a PR; draft any comment for the user, with the line to put it on.

Snapshot

Read and run everything in a snapshot of the target's head, never in the user's checkout. In the checkout, run only the commands below; even git status and git diff can rewrite its index.

1. Clone the checkout into a new temporary directory with git clone --shared --no-checkout. Resolve refs to SHAs in the checkout with git rev-parse, because the snapshot's origin/<branch> is the checkout's local branch.
2. Check out the head:
   • For a PR, fetch pull/<number>/head from the PR's repository URL and confirm it matches headRefOid. Pass the PR URL to every gh pr command, because gh can't find the repository from the snapshot. If the checkout isn't a clone of that repository, clone the repository instead.
   • For uncommitted changes, check out HEAD, then list the changed paths in the checkout with git diff-index --name-only HEAD and git ls-files -o --exclude-standard. Copy each into the snapshot, keeping symlinks as links, or delete it there if the checkout no longer has it.
   • For a merge commit, read the change with git show --first-parent.
3. Install dependencies only with the repository's locked install command, such as npm ci. If a check needs ignored config such as .env, list it as unverified instead of copying the config.
4. Record the head SHA. Before reporting, look it up again, and for uncommitted changes rerun both path lists and compare every path on the old or new lists with its snapshot copy. If anything changed, update the snapshot and review again.