Rebase onto Updated Parent Branch

Rebase the current branch onto a parent branch that has been updated.

Usage

/rebase-parent
/rebase-parent feature/parent-branch    # Explicit parent branch

Instructions

1. Identify Parent Branch

If not provided, try to determine the parent:

# Get current branch
git branch --show-current

# Check PR base branch
gh pr view --json baseRefName --jq '.baseRefName'

If the base is main, this skill doesn't apply - use /rebase-main instead.

Ask the user to confirm the parent branch if uncertain.

2. Check Current State

# Check for uncommitted changes
git status --porcelain

# Get current branch
git branch --show-current

Stash or commit uncommitted changes before proceeding.

3. Fetch Latest Parent

git fetch origin {parent-branch}

4. Find the Fork Point

The tricky part with rebasing onto an updated parent is finding where your branch originally diverged. If the parent was rebased, the old base commits are gone.

# Get the merge base (may be outdated if parent was rebased)
git merge-base HEAD origin/{parent-branch}

# Count commits unique to your branch
git rev-list --count origin/{parent-branch}..HEAD

5. Perform the Rebase

Use --onto to rebase only your commits onto the new parent:

# Find how many commits are yours (after the original fork point)
# Then rebase those commits onto the updated parent

git rebase --onto origin/{parent-branch} $(git merge-base HEAD origin/{parent-branch}) HEAD

If that doesn't work cleanly (merge-base is stale), try:

# Interactive rebase to select only your commits
git rebase -i origin/{parent-branch}

6. Handle Conflicts

If conflicts occur:

1. List conflicting files: git diff --name-only --diff-filter=U
2. Resolve each conflict
3. Stage resolved files: git add {file}
4. Continue: git rebase --continue

If stuck, abort and ask for guidance: git rebase --abort

7. Force Push

git push --force-with-lease

8. Update PR Base (if needed)

If the PR base branch needs updating:

gh pr edit --base {parent-branch}

9. Report Result

Inform the user:

• Successfully rebased X commits onto {parent-branch}
• Conflicts resolved (if any)
• Force pushed to origin