toy-crane Pull base branch
Bring the current checkout onto the latest requested remote base through a rebase so the history remains linear. When the request does not name the base, resolve the remote's advertised default branch rather than assuming its name.
Preserve all local work. A dirty working tree is not authority to commit, stash, or discard its contents; leave it intact and identify what prevents a safe update. Fetch the remote truth before deciding whether any update is needed.
Rebase rather than introducing a merge commit. Resolve a conflict when the intended result is established by the request and project evidence. When intent is ambiguous, keep the original work recoverable and report the conflicting files and the smallest decision needed to continue.
Finish when the checkout is based on the fetched target branch, local work is preserved, and the user knows the resolved remote and base, whether it was already current, or which commits arrived.