Rebase Branch

Introduction

Rebase the current branch onto the latest base branch, resolving any merge conflicts by preserving the intent of local changes. Optionally force-push and monitor CI status on GitHub.

Arguments

<arguments> $ARGUMENTS </arguments>

Supported arguments:

• push — After a successful rebase, force-push the branch upstream and monitor GitHub Actions CI until completion.

Main Tasks

1. Assess Current State

Understand the branch topology and working tree before doing anything destructive.

1. Run git status to check for uncommitted changes.
2. Run git branch --show-current to identify the current branch.
3. Determine the base branch (the long-lived branch this feature branch should land on):

   • Prefer the repository's default branch. Detect it with:

     git symbolic-ref --short refs/remotes/origin/HEAD 2>/dev/null

     This typically returns origin/main, origin/master, origin/develop, or origin/stable. Use the branch name after origin/.

   • If origin/HEAD is not set, fall back to whichever of main, master, develop, or stable exists on the remote.
   • If the current branch was clearly forked from a different long-lived branch — including a release branch (e.g. release/*, release-*, or a version-named branch like 1.2/v1.2) — use that instead.
   • When the base branch is still ambiguous, ask the user which branch to rebase onto.
4. If the current branch IS a long-lived branch — STOP: Rebasing these branches is not allowed. Inform the user and exit. Long-lived branches include the detected default branch, main/master/develop/stable, and release branches (release/*, release-*, version-named branches).
5. If there are uncommitted changes — STOP: Inform the user they must commit or stash changes before rebasing. Do not proceed.
6. Show the user a summary:
   • Current branch name.
   • Base branch.
   • Number of local commits (git log origin/<base-branch>..HEAD --oneline).

2. Update Base Branch & Rebase

1. Fetch the latest remote state:

   git fetch origin

2. Start the rebase:

   git rebase origin/<base-branch>

3. If the rebase completes cleanly, skip to Phase 4.

3. Resolve Merge Conflicts

When conflicts arise, understand what the local commits intended to do and preserve that intent while incorporating upstream changes. For each conflict, read both sides and make an informed resolution.

For each conflict that arises during the rebase:

1. Identify conflicting files:

   git diff --name-only --diff-filter=U

2. For each conflicting file:
   • Read the file to see the conflict markers.
   • Inspect the commit currently being replayed — that is REBASE_HEAD, not HEAD (git show REBASE_HEAD, or git log -1 REBASE_HEAD). Mid-rebase, HEAD points at the last successfully applied commit, not the one that is conflicting.
   • Understand what the upstream change did vs what the local change intended.
   • Resolve the conflict by preserving the intent of local changes while incorporating any non-conflicting upstream changes.

   • Stage the resolved file:

     git add <file>

3. Continue the rebase:

   git rebase --continue

4. Repeat until the rebase completes. If a conflict is ambiguous, present both sides to the user and ask how to resolve it.
5. After all conflicts are resolved, show the user a summary of what was resolved.
6. Escape hatch. If a conflict is unresolvable, or the user wants to bail out at any point, run git rebase --abort to restore the branch to its exact pre-rebase state — nothing is lost. Never leave the user stranded in a half-finished rebase.

4. Verify Rebase Result

1. Run a quick sanity check:

   git log origin/<base-branch>..HEAD --oneline

2. Confirm the commit history looks correct (same number of local commits, no duplicates).
3. If the project defines fast validation commands (formatters, linters), run them to catch any issues introduced by conflict resolution. Discover them from the project's own context — for example AGENTS.md/CONTAINER-style docs, a Makefile/Taskfile/justfile, package.json scripts, pyproject.toml/tox.ini, or a pre-commit config. Run whatever the project actually defines, then fix any issues introduced by conflict resolution. If the project defines no such commands, skip this step.

5. Force Push & Monitor CI (only when push argument is provided)

Skip this phase entirely if push was NOT passed as an argument. Instead, inform the user the rebase is complete and they can push when ready.

When push IS provided:

1. Force-push the rebased branch:

   git push --force-with-lease origin <branch-name>

   Use --force-with-lease as a safety measure to avoid overwriting unexpected upstream changes.

   Note: the git fetch origin in Phase 2 already advanced the remote-tracking ref that a bare --force-with-lease compares against, so a concurrent push to this branch between the fetch and the push would not be caught. If that risk matters, pin the SHA captured before the fetch: git push --force-with-lease=<branch-name>:<sha> origin <branch-name>.

2. Discover the run the push triggered (be patient — CI can take several minutes to start):

   gh run list --branch <branch-name> --limit 5

   If nothing has started after a few minutes, investigate whether the push triggered a workflow.

3. Wait for the run to finish with a single blocking call instead of polling repeatedly:

   gh run watch <run-id> --exit-status

   --exit-status returns non-zero if the run fails, so you can branch on the result directly. Fall back to periodic gh run list only if gh run watch is unavailable.

4. If any jobs fail:

   • Read failure logs:

     gh run view <run-id> --log-failed

   • Analyze the failure and propose a fix to the user.
   • After approval, commit the fix, push, and continue monitoring.
5. Report final CI status to the user.

Notes

Branch Safety:

• This skill will NEVER rebase a long-lived branch — the repository's default branch, main/master/develop/stable, or a release branch (release/*, release-*, version-named branches).
• Uses --force-with-lease instead of --force to prevent overwriting unexpected remote changes.
• Will not proceed with uncommitted changes in the working tree.
• git rebase --abort always restores the exact pre-rebase state — use it whenever a rebase cannot be completed cleanly rather than leaving the branch half-rebased.

Conflict Resolution Strategy:

• Local changes take priority — the goal is to land our work on top of the latest base.
• When both sides modify the same logic in incompatible ways, ask the user.
• After resolution, run the project's formatters/linters (if any) to catch issues introduced by the merge.

Common Mistakes

• Rebasing onto the wrong base. Confirm the detected base branch with the user before starting — landing work on the wrong long-lived branch is painful to unwind.
• Forgetting the abort path. When a conflict cannot be resolved cleanly, git rebase --abort is the way back. Don't leave the user stranded mid-rebase.
• Resolving by blindly taking one side. Accepting one side wholesale (e.g. -X ours/-X theirs) discards intent. Read both sides and preserve what the local commit meant to do.
• Inspecting HEAD during a conflict. The commit being replayed is REBASE_HEAD, not HEAD. Looking at HEAD shows the wrong commit.
• Force-pushing without --lease. Plain git push --force can silently clobber a teammate's push. Always use --force-with-lease.
• Counting commits against a stale local base. Use origin/<base-branch>..HEAD, not the local ref, or the count can be wrong on an out-of-date or freshly cloned checkout.

Expected Outcome

A branch that:

• Is cleanly rebased onto the latest base branch.
• Has all merge conflicts resolved preserving local intent.
• Passes the project's formatters and linters (if defined) after resolution.
• (When push is provided) Is force-pushed upstream with passing CI.