Rebase Downstream

Rebase Downstream Tree

Rebase a tree of dependent branches after upstream changes have been made.

Auto-detects the downstream branch tree (including sibling branches), rebases

each branch in order, resolves conflicts when possible, and runs preflight

checks on each branch.

Current State

• Branch: !git branch --show-current
• Status: !git status --short

Steps

1. Detect current branch

Get the current branch name. This is the branch that was just modified and whose

changes need to propagate downstream.

git branch --show-current

2. Auto-detect downstream chain

Run the detect-chain.sh helper script to find all downstream branches:

bash .claude/skills/rebase-downstream/detect-chain.sh <current-branch>

The script outputs branch:parent per line in rebase order (depth-first

pre-order). This handles both linear chains and trees with sibling branches.

3. Confirm the chain

Display the detected chain to the user and ask for confirmation before

proceeding.

If no downstream branches are detected, report this to the user and stop.

If branches are detected, show the tree visually:

<current-branch>
  → <child1>
    → <grandchild1>
  → <child2> (sibling)

Ask the user to confirm before rebasing. If the user declines, stop.

4. Rebase each branch in order

For each downstream branch (closest to the current branch first):

• Checkout the branch:

   git checkout <downstream-branch>

• Rebase onto its parent (from the branch:parent output):

   git rebase --fork-point <parent-branch>

--fork-point uses the parent branch's reflog to find the actual fork point,

so only the branch's own commits are replayed. Without it, if the parent was

rebased/amended, git replays already-applied parent commits with different

SHAs, causing duplicate commits and false conflicts.

The parent for each branch is provided by the detect script. For sibling

branches, both share the same parent.

• Handle conflicts (if any):

• Inspect each conflicted file to understand both sides
• Attempt to resolve the conflict intelligently
• After resolving, stage the files and continue:

     git add <resolved-files>
     git rebase --continue

• If a conflict cannot be resolved, abort and stop:

     git rebase --abort

Report which branch and files had unresolvable conflicts, then stop

entirely. Do NOT continue to the next branch.

• Run full preflight checks using /preflight on this branch. This

includes format, gn_check, presubmit, build, and tests. If preflight fails,

stop and report. Do NOT continue to the next branch.

• Move to the next branch only after successful rebase and preflight.

5. Return to the original branch

After all branches are rebased successfully, checkout the original starting

branch:

git checkout <original-branch>

6. Report results

Summarize the results:

• Rebased branches: List each branch that was successfully rebased
• Conflicts resolved: Note any conflicts that were auto-resolved and how
• Preflight results: Summary of preflight status for each branch
• Tree: Show the full rebased tree structure

Important

• NEVER skip preflight checks on any branch in the chain
• Stop immediately if a rebase conflict cannot be resolved
• Stop immediately if preflight fails on any branch
• Always return to the original branch at the end (even on failure)
• Do not force-push any branches — the user will decide when to push