Use TDD only when the user asked for it or the repository requires it. Follow the repo testing MDX and (or the stack's test skill). Do not commit unless asked. 1. Red: write a failing test for the desired behavior. Use real APIs where the repo tests do; mock only at documented boundaries. 2. Green: write the smallest implementation that passes that test. 3. Refactor: improve structure while tests stay green. 4. Repeat for the next increment. Run the focused test file each cycle, then the affected suite. 5. Docs: if behavior or commands changed.