Git Branch Sync

Catch current branch up to base. Rebase only. Surface conflicts.

Flow

1. Parallel:
   • git status --porcelain
   • git branch --show-current
   • git rev-parse --abbrev-ref --symbolic-full-name @{u} (upstream if any)
   • Rebase/merge already in progress (git status says so) or detached HEAD (git branch --show-current empty) -> stop with a one-line explanation. Why -> a second git rebase on top of a half-finished one errors confusingly, and there is no current branch to sync
2. Base: user names one -> verbatim. Else detect: git symbolic-ref --short refs/remotes/origin/HEAD -> strip the origin/; ref missing -> git remote set-head origin -a, re-read; no remote -> main, fall back master. Why -> rebasing onto main in a develop-based repo replays the branch onto the wrong parent and manufactures conflicts that aren't real
3. Dirty -> stash: git stash push -u -m "sync-branch auto-stash". Pop later. Unsafe (unresolved merge) -> stop + tell user
4. On base -> git pull --ff-only origin <base>. Fails (local base diverged) -> pop the stash if step 3 made one (nothing was rewritten), then stop + tell user. No auto-rebase of base itself
5. Else:
   • git fetch origin <base>
   • git rebase origin/<base>
   • No remote -> skip the fetch, git rebase <base> (local ref). Local <base> absent too -> nothing to sync against; pop the stash if step 3 made one, stop + say so
6. Conflicts:
   • git status -> list conflicted paths
   • Stop + surface. No auto-resolve
   • Tell user: resolve, git add <paths>, git rebase --continue. Mention git rebase --abort escape
   • Leave stash in place. Tell user to pop after resolve
7. Rebase done (clean or aborted) -> pop stash if created
8. Print one-liner: branch, base, commits replayed (git rev-list --count origin/<base>..HEAD before the rebase vs after), force-push needed? (yes = upstream exists and history was rewritten)
   • 0 commits replayed (already up to date) -> say so explicitly; don't mention force-push (nothing rewritten)

Rules

• Always rebase, never merge. Why -> user workflow preference; linear history. Don't offer merge as alternative even on shared branches; surface the risk (force-push needed) and let user decide
• Never force-push here. Pushed branch rebased -> tell user git push --force-with-lease. Let user run
• Never git rebase --skip / drop commits to "make it work". Surface conflict
• Never --no-verify. Why -> hooks gate broken state; skipping just defers the failure
• No upstream -> sync vs origin/<base>. Note branch not pushed
• Pop stash you made on rebase clean OR abort. Pop blocked by conflicts -> leave stashed + tell user