Cut a working branch for one issue and check it out. Git only — planning or implementation marks work started per references/issue-tracker.md.

Name the branch

Take the issue from the argument — an id or URL. With no argument, use the issue under discussion. Read its title and type from the tracker.
Pick the conventional type from the issue itself: feat, fix, docs, style, refactor, perf, test, build, ci, or chore. Derive it from the issue's own type field or labels; ask the user only when the issue gives no signal.
Build <type>/<issue-id>-<slug>, where slug condenses the issue to ≤7 words, lowercased and hyphen-separated, e.g. feat/42-add-meaning-to-universe.

Cut it

git checkout -b <branch-name> — it forks from the current branch, so cut from the branch you mean to base the work on.

Done when the branch exists and is checked out.