Spec and Code as Co-Artifacts Stable Relative to Model

Spec alone is unstable across models; the pair (spec, code) is stable relative to a given model and harness.

Spec-driven development converges where tests pass for M1. That point is not directive-gap closed. It is M1’s confabulations filling gaps in ways that align with intent: the hidden directive gap. Treating (spec, code) as co-artifacts makes stability explicit and complements two-layer-governance-model. architecture-orphaning shows why specs cannot enforce this layer, so model upgrades become compiler upgrades that must re-validate existing behavior.