Drop the middle leg and the spec is only being compared to itself

Agentic Engineering Is Pattern Engineering

A green test suite an AI agent wrote doesn't prove it built what the spec asked for — it can compare a value to itself and still pass. The fix is a structural pattern: every spec field must be enforced by code, every reference must resolve, and every comparison must actually run, tracked and audited afterward. A three-way check — expected value, independent reference calculator, and production output — catches drift a suite testing itself against itself cannot.