New Branch (create a branch off the latest mainline)

Branch off the latest origin/main so the starting point is clean and in sync with the remote.

Trigger

The user asks to "create a new branch / new branch / cut a branch" and wants it based on the latest mainline.

Scope (important)

This skill is only responsible for quickly creating a clean new branch, up to "verify right after cutting".

• Do: fetch → branch from origin/main → verify sync → output confirmation.
• Do NOT: explore / read code, spawn Explore / Plan agents, produce an implementation plan, or start writing code.

Any requirement description the user includes at trigger time (e.g. "improve the add-to-slack onboarding flow") is only used to derive the branch name / record intent, not a dev task to start here. Follow-up requirement refinement and implementation are discussed by the user in a new conversation and are out of scope for this skill.

Pre-checks

1. Confirm the branch name (always in English, following the <type>/<short-desc> convention, e.g. feat/credit-guard, fix/stream-recovery):
   • User already gave a ready branch name → use it directly.
   • User gave a requirement sentence (e.g. "improve the add-to-slack onboarding flow") → derive an English branch name from it (e.g. feat/slack-onboarding-flow) and create it directly, no need to ask.
   • No derivable information at all → only then ask.
2. Confirm the working tree is clean (git status). If there are uncommitted changes, stop and ask the user how to handle them; do not force-switch.

Steps

# 1. Fetch the latest remote mainline
git fetch origin main

# 2. Create and switch to the new branch off the latest origin/main
git checkout -b <branch-name> origin/main

# 3. Verify: should be 0 ahead, 0 behind
git rev-list --left-right --count origin/main...HEAD

git checkout -b <name> origin/main in one step guarantees the new branch's start = the latest remote mainline; no need to update local main first.

Verification

• git rev-list --left-right --count origin/main...HEAD outputs 0 0 (0 ahead, 0 behind).
• git status shows you are on the new branch with a clean working tree.

Output confirmation: branch name, current HEAD commit, and sync status against origin/main.

When to stop and ask

• No ready branch name and no derivable requirement description → ask.
• Uncommitted changes in the working tree → ask how to handle (stash / commit / discard); never discard on your own.
• A branch with the same name already exists → ask whether to overwrite or rename.

Key principles

• Start from the latest: always base on origin/main, never on a possibly stale local main.
• Never lose changes: confirm before any operation that could lose the user's work.
• Verify right after cutting: use rev-list to confirm actual sync; never assume.