TDD

Protect meaningful behavior with the smallest useful test set. Match the request: ordinary testing, regression work, or a requested test-first loop. A tests-only request keeps production changes outside its scope.

Contract

Read the relevant public surface, callers, existing tests and repository conventions. Identify the caller-visible contract, important failure risk and cheapest boundary that exercises it. Reuse accepted decisions; resolve only real contract ambiguity. Keep production APIs product-driven.

Minimum