Verification gate

A verification gate is a check the model cannot argue its way past, because the harness enforces it rather than the model. A hook that blocks a transition on the harness's blocking exit code is one shape; pre-commit hooks and required CI status checks on a protected branch are the same shape. Prefer deterministic graders where you can get them: a validator can prove a field is missing, where a model can only argue that its work is complete.