Agent Skills: git-rebase-sync

git-rebase-sync

Use this skill when you need to sync a feature branch onto the latest origin/{base_branch} via git rebase, including conflict resolution with explicit clarification questions when intent is ambiguous.

Goals

• Rebase the current branch onto a specified base branch (often the repo default branch like dev or main).
• Resolve conflicts deliberately, without guesswork.
• Keep safety rails: backup ref, confirmations before history-rewriting commands, and safe pushing.

Hard Rules

• Do not create or switch to a different feature branch. Operate on the current branch name unless I explicitly ask otherwise.
• Before any history-rewriting command (git rebase ..., git push --force*), print the exact command(s) you will run and wait for my confirmation.
• Create a local backup ref (prefer an annotated tag) before starting the rebase. Do not push backup refs unless I explicitly ask.
• Prefer git push --force-with-lease, never plain --force.
• If the correct conflict resolution is unclear, stop and ask a targeted question. Do not invent product behavior.

Workflow

1) Identify base + branch

• Determine the current branch:
  • git branch --show-current
• Determine the base branch you will rebase onto:
  • If not provided, use GitHub default branch:
    • gh repo view --json defaultBranchRef --jq '.defaultBranchRef.name'
• Fetch latest:
  • git fetch origin

2) Preflight safety checks

• Ensure the working tree is clean and there is no operation in progress:
  • git status
• If git status indicates an in-progress merge/rebase/cherry-pick, stop and ask what to do (abort vs continue).

3) Create a local backup ref (do not push)

• Create an annotated tag at current HEAD:
  • git tag -a {branch_name}-rebase-backup-$(date +%Y%m%d-%H%M%S) -m "pre-rebase backup" HEAD
• Record the tag name as {backup_ref} for recovery.

4) Choose rebase mode (normal vs preserve merges)

• Check whether the branch contains merge commits:
  • git rev-list --count --merges origin/{base_branch}..HEAD
• If merge commits exist, ask whether to preserve them (--rebase-merges) or flatten them (plain rebase).

5) Detect stacked branches (will they follow the rebase?)

Other local branches may point at intermediate commits in the range being rewritten (origin/{base_branch}..HEAD) — common with phased NN-description stacks. A plain rebase rewrites those commits and orphans the stacked branches on the old, pre-rebase commits (along with every open PR built on them). --update-refs (the default in step 6) moves them onto the rewritten commits instead. Enumerate them so you can report what the rebase will carry along:

# Branches pointing into the range being rewritten — these get orphaned by a
# plain rebase and require --update-refs to follow the rewrite.
cur=$(git branch --show-current)
git for-each-ref --format='%(refname:short)' refs/heads | while read -r br; do
  [ "$br" = "$cur" ] && continue
  if git merge-base --is-ancestor "$br" HEAD \
     && ! git merge-base --is-ancestor "$br" origin/{base_branch}; then
    echo "stacked: $br ($(git rev-parse --short "$br"))"
  fi
done

• Report the detected stacked branches to me before rebasing.
• A branch that is checked out in another worktree is skipped by --update-refs (git will not move a checked-out branch); flag these so I can verify them manually after the rebase.

6) Run the rebase (requires confirmation)

• Default to --update-refs so any stacked branch pointing into the rewritten range follows the rewrite instead of being orphaned.
• Print the exact command you intend to run, then wait for confirmation:
  • Default:
    • git rebase --update-refs origin/{base_branch}
  • With merge preservation:
    • git rebase --rebase-merges --update-refs origin/{base_branch}
• To make this the permanent default without the flag: git config --global rebase.updateRefs true.

7) Conflict handling loop

When conflicts happen:

1. Collect context:
   • git status
   • Identify conflicted files (from status output).
2. For each conflicted file:
   • Open the file and understand the surrounding code and intent.
   • Prefer minimal, mechanical conflict resolutions:
     • Keep upstream changes unless the feature branch deliberately supersedes them.
     • Re-run generators (lockfiles, codegen) instead of hand-editing when appropriate.
   • If intent is ambiguous, ask a single targeted question, for example:
     • "Should we keep the new upstream behavior X, or keep the feature behavior Y?"
     • "Is this file generated and safe to regenerate, or do you want manual resolution?"
3. Apply the resolution, then stage only resolved files:
   • git add <file...>
4. Continue:
   • git rebase --continue
5. If you reach a point where resolution is too risky/unclear:
   • Stop and ask; optionally propose aborting the rebase.

Helpful commands during conflicts:

• Inspect current conflict hunks: git diff
• See the commit being replayed: git show
• If you need to back out: git rebase --abort (this is safe and should be preferred over destructive resets)

8) Post-rebase verification

• Show the new commit range:
  • git log --oneline --decorate origin/{base_branch}..HEAD
• Confirm each stacked branch from step 5 moved onto the rewritten range. git rebase --update-refs prints an "Updated the following refs with --update-refs" summary; the moved branch refs should also appear as decorations on the new commits in the log above. Note any that did not move (e.g. checked out in another worktree) for manual handling.
• Run appropriate repo checks (tests, typecheck, lint) if available.

9) Push updated branch(es) (requires confirmation)

• If the branch already exists on origin, rebasing rewrites history, so pushing requires force-with-lease.
• --update-refs only moves local refs. A normal git push updates the current branch only — each stacked branch (from step 5) that also exists on origin must be force-pushed individually.
• Print the exact command(s) and wait for confirmation:
  • Current branch:
    • git push --force-with-lease origin HEAD:{branch_name}
  • Each moved stacked branch that exists on origin (repeat per branch):
    • git push --force-with-lease origin {stacked_branch}
• Any branch skipped because it is checked out in another worktree was not moved — verify it before pushing.

Recovery

• If something goes wrong, use {backup_ref} to restore the pre-rebase state.
• Do not run destructive commands (e.g., git reset --hard) unless I explicitly confirm after you show the exact command.