The spec-completeness problem here is the same one that bites distributed systems verification: the proof holds inside an operating envelope (no adversarial inputs, trusted runtime, bounded sizes), and the interesting failures live at the boundary. TLA+ has the same property - you can prove liveness under a fairness assumption the deployment silently violates, and nothing in the proof tells you when reality drifted outside.

What I'd actually want from the tooling is a machine-checkable statement of the envelope itself, propagated as a runtime guard rather than a compile-time comment. Then "proof holds" and "we are still inside the proof's domain" are two separate, observable properties, and the unverified-parser / unverified-runtime cases stop being invisible.