Carries a code change through to a tested, verified and reviewed local change, loading the stage skill for each step: planning, test-first implementation, debugging, verification and review. Use when a request asks for code to change, whether it arrives as an approved ticket or a one-line message: a bug fix, a failing test or crash, a small feature or flag, a behavior change, or review comments to fix. Not for questions about the code, for merging or deleting a finished branch, or for deciding which review comments to accept without changing code. Use it whenever the work will change code, even when the user does not mention tests, review or a pull request.