ground-mechanismlisted

# Skill: Mechanism > "The model decides. Code enforces. Never the reverse." ## The Standard - **Model decides, code enforces**: if a model's output *is* the enforcement, there is no enforcement. - **Never let a model report its own oracle result**: run the command in code, read the exit code in code. - **One answer means code**: a single correct answer is computable. A space of acceptable answers is judgment. - **Replay means code**: billing, audit, security, migrations. A model is not reproducible across versions, and versions change underneath you. ## The Check Ask yourself: - One correct answer, or a space of acceptable ones? - Must this replay identically? - Is the input space enumerable? A model choosing between four known branches is an expensive, non-deterministic switch statement. - If this is wrong, will anyone notice? Silent wrongness with a wide blast radius is code, or a model behind a gate. ## The Surface Frequency × ambiguity. Not a binary. | | Low ambiguity | High ambiguity | |---------------------|-----------------------------------|--------------------------------------| | **High frequency** | Code. The economics compound. | Model — and promote aggressively. | | **Low frequency** | Either. Don't over-engineer. | Model. Encoding never pays back. | ## The Migration The line moves. Both ways. - **Promote** judgment → code when it recurs identically. It gets cheaper forev