Test-Driven Development

Write tests first, implement minimal code to pass, refactor systematically.

<when_to_use>

• New features with TDD methodology
• Complex business logic requiring coverage
• Critical paths: auth, payments, data integrity
• Bug fixes: reproduce with test, fix, verify
• Refactoring: ensure behavior preservation
• API design: tests define the interface

NOT for: exploratory coding, UI prototypes, static config, trivial glue code

</when_to_use>