Use when implementation work is about to touch code (branch before the first commit), when a built task needs to ship as a pull request, when defining how branches, commits, and PRs map to plan tasks, or when parallel agents share one repository. Triggers on "create a branch", "commit this", "open a PR", "ship this task", "how do we merge", task start or completion during an implementation plan, worktree setup, or noticing commits landing directly on main.
