git-rebase-branch

name	git-rebase-branch
description	Rebase the current branch onto the latest default branch (detected dynamically from the remote — main, develop, or whatever origin/HEAD points to), safely. Use when the user asks to rebase, update their branch with the default branch, sync with the default branch, resolve a "branch is behind" state, or before pushing/opening a PR. Protects the default branch: if HEAD is on it, it carves a speaking feature branch from the last commit FIRST and never rebases the default branch itself. Attempts safe automatic conflict resolution and only asks the user to arbitrate genuine conflicts. Triggers on: "rebase", "rebase on main", "update my branch", "sync with main", "my branch is behind", "rebase before pushing".
allowed-tools	Bash, AskUserQuestion
version	1.0.0
changelog	[{"version":"1.0.0","date":"2026-07-09T00:00:00.000Z","changes":["Initial release"]}]
created-at	"2026-07-09T00:00:00.000Z"
created-by	Jeremy Wallez <[e-mail]>

Git Rebase onto Default Branch

Overview

Rebase the current branch on top of the latest remote default branch (detected dynamically — main, develop, or whatever origin/HEAD resolves to), keeping history linear before a push or PR. The default branch itself is never rebased — if you are on it, a speaking feature branch is carved first.

Workflow

1. Detect the default branch

# Primary
DEFAULT=$(git symbolic-ref --short refs/remotes/origin/HEAD 2>/dev/null | sed 's@^origin/@@')

# Fallback if origin/HEAD is not set
if [ -z "$DEFAULT" ]; then
  git remote set-head origin --auto >/dev/null 2>&1
  DEFAULT=$(git remote show origin | sed -n 's/.*HEAD branch: //p')
fi
echo "Default branch: $DEFAULT"

2. Inspect state

CURRENT=$(git rev-parse --abbrev-ref HEAD)
echo "Current branch: $CURRENT"
git status --porcelain

If the working tree is dirty, stop and tell the user to commit or stash first (this skill does not stash silently). If HEAD is detached, stop and report.

3. Fetch the latest default branch

git fetch origin "$DEFAULT"

4. Safety — never rebase the default branch

If CURRENT equals $DEFAULT, do not rebase it. Carve a speaking branch from the current commit, then reset the local default to the remote:

Speaking branch name — parse the last commit subject git log -1 --pretty=%s:

• <type>(scope): desc → <type>/<scope>-<desc-kebab>
• <type>: desc → <type>/<desc-kebab>
• kebab-case the description (lowercase, non-alphanumerics → -, collapse repeats, trim), truncate to ~60 chars.

git switch -c "<speaking-branch>"
git branch -f "$DEFAULT" "origin/$DEFAULT"   # keep local default clean, no rebase of it
CURRENT="<speaking-branch>"

Report the new branch name to the user. Now proceed to rebase this new branch.

5. Rebase

git rebase "origin/$DEFAULT"

• Clean result → done, continue to output.
• Conflict → go to Step 6.

6. Conflict handling

Attempt safe automatic resolution only when it is unambiguous:

git diff --name-only --diff-filter=U   # list conflicted files

Safe-auto cases (resolve, git add, then git rebase --continue):

• Pure import/whitespace/formatting overlap with no logic divergence.
• One side only adds lines the other doesn't touch (non-overlapping hunks git flagged conservatively).
• Lockfiles/generated files that can be regenerated deterministically.

For any genuine logic conflict (both sides changed the same statements with different intent), do not guess. Use AskUserQuestion to let the user arbitrate per file/hunk (options: keep ours / keep theirs / describe the merge). Apply the choice, git add <file>, then:

git rebase --continue

Never leave the repo mid-rebase silently. If the user cannot decide or asks to stop:

git rebase --abort   # returns to the pre-rebase state

and report that a manual rebase is required.

7. Output

✔ Rebased <branch> onto origin/<default>
  <n> commits replayed

If a branch was carved from the default branch, state it explicitly:

ℹ Was on <default> — carved branch <speaking-branch> before rebasing (default branch untouched)

Git Safety Protocol

• NEVER rebase the default branch (main, develop, …) — carve a feature branch first
• NEVER run --force / force-push without an explicit user request
• NEVER update git config
• NEVER stash or drop the user's uncommitted work silently — stop and ask
• On unresolved conflict, prefer git rebase --abort over leaving a broken state