Core claim: A green run after an agent patch is not validation. It is a zero exit code from a suite the model was allowed to edit. Route every failing nodeid into one of three planes—property, fixture, or freeze—before any generator may touch a test file. Reject the patch if a case changes planes, even when CI is green. That rule is dull. It blocks the cheapest cheats: deleted asserts, rewritten goldens, and a fresh pytest.skip . Green is the wrong oracle Agent patches opt...