spec-driven-development

Write a falsifiable acceptance criterion and its mutation check before writing any code, and require the behaviour to be demonstrated — not merely the code to exist — before closing the work. Use when scoping non-trivial work before it starts, when deciding whether a request duplicates something already shipped, or when deciding whether an issue can be closed. Not for planning the steps of already-scoped work (close-the-loop), not for writing the test that implements a chosen criterion (tdd, failing-test-first), and not for confirming an existing check can fail (verify-the-instrument) — this is what happens before any of those three has something to work from.