L3_7 Admissible Interior Rigidity

This paper establishes a rigidity theorem for the admissible interior of a closed epistemic system. It proves that once admissibility is saturated by constraints and standing is conserved, the interior admits no deformation, reparameterization, or alternative configuration without collapse. Apparent flexibility is shown to be illusory, arising only from illicit scope transport or hidden degrees of freedom. The argument is strictly eliminative and non-constructive: it introduces no new primitives, specifies no procedures, and provides no operational characterization. The result serves as a boundary theorem, fixing the admissible interior as rigid by necessity rather than by design or convention.