Test Driven Development

The skill gates you before letting production code through without a failing test first, which sounds rigid until you realize how often "I'll add the test later" means never. It includes a preflight check that routes medium or high complexity work to planning before you start the TDD cycle, so you're not test-driving your way into the wrong architecture. Also has a pre-edit complexity check to stop you from cramming logic into an already overloaded file just because the test is green. Useful when you want the discipline enforced, not just suggested.