After implementing any significant feature (new auth method, new API endpoint, new environment variable, new UI flow, etc.), add a section to README.md documenting it. Follow the existing style: plain prose "How it works" explanation, an environment-variables table if applicable, and setup/local-testing steps. Place the new section near related content (e.g. a new auth method goes near "Password reset").
Use test-driven development: write failing tests first, then write the implementation to make them pass. Run tests to confirm they fail before implementing, and again after to confirm they pass.