When doing a code review, follow these rules.

Determining what to review

Choose the review scope from the user's request:

No target: The staged and unstaged diffs, plus untracked files and their contents.
Commit: The commit metadata and patch.
Branch or base ref: The merge-base, commits since that base, and the branch diff. If the branch is already merged, its historical base and head from pull-request metadata.
Pull request URL or number: The pull-request context, base and head commits, commit list, and historical diff. For a merged pull request, include its historical iteration or merge metadata. Treat a bare number as a pull request only when the request or repository provider makes this clear.

If the requested target or provider metadata is unavailable, report that instead of choosing a different review scope.

Identifying the spec source

Look for the intended requirements in this order: