The Kuiper Cliff, Planet Nine Null, and the Oort Boundary under the MMA-DMF Active-Vacuum Ontology

We report a bounded outer-Solar-System boundary audit under the MMA-DMF active-vacuum ontology. The claim set is deliberately narrow: the Kuiper Cliff is treated as a finite-width anchored depletion/onset response rather than as a literal hard wall; the 50–80 AU region is treated as a post-Neptune/post-Kuiper transition regime; Planet Nine is not required or supported as the primary cause of the tested Kuiper-Cliff signal; Sedna is retained as a directly tracked boundary-anchor object through a mechanism-lock transfer; and the Oort layer is retained only as a bounded external-boundary/external-perturber proxy. Static public-comet catalogues are excluded as a direct positive Gamma_vac validation architecture because the tested catalogue construction is radial/semi-major-axis proxy dominated after radial and external-radius controls. The Kuiper-Cliff result is supported at the family level. The best BIC representative is the asymmetric finite-width anchor kernel M2c, with a_K = 47.733027 AU fixed by the Neptune 2:1 scale. The family-level bootstrap support is 0.98 when the admissible finite-width representatives are grouped, while hard-wall and one-sided-wall controls are rejected. The strongest direct population consequence is the classical-object absence in the 55–80 AU post-tail window: the pre-window contains 202 classical and 57 non-classical objects, while the post-tail window contains 0 classical and 38 non-classical objects, giving Fisher’s exact-test probability p = 3.2795 × 10^-22. This morphology supports finite-width depletion/onset behavior; it does not prove an exact discontinuous wall. The Planet Nine result is a bounded null. It says that a new massive Planet Nine perturber is not needed as the primary explanation for the tested 35–80 AU depletion/onset component. It does not assert global nonexistence of every possible distant planet-like body. The Sedna branch is likewise bounded: the claim is a mechanism-lock transfer into a directly tracked detached object, not a Sedna-only curve fit and not a direct proof of the Oort Cloud. The Oort branch is a transition-proxy branch: external tide/impulse controls are negligible at the Kuiper anchor and become relevant at Oort-scale radii, but the paper does not claim direct Oort Cloud measurement. The final retained status is COMPLETE_SUCCESS_WITHIN_DECLARED_SCOPE.