new-branch

# 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 ar...