Consequence Closure: Semantic Assurance at the Machine Action Boundary

Consequence Closure is a carrier neutral assurance framework for determining whether the consequence of a concrete machine action is already fixed by the evidence available at a declared action cut. When compatible realizations still produce different consequences, the framework preserves relational counterexamples as materiality witnesses and derives inclusion minimal semantic obligation sets over a declared candidate vocabulary. Obligations remain separate from realizable Establishments, including observations and interventions, and from Routes that use them to reach closure. The note develops an exact materiality hypergraph characterization and a finite CEGIS procedure for obligation synthesis, a claim indexed P0/P1/P2 hierarchy for preserving closure, obligation, and Route semantics across source to Core compilation, and an inspectability contract for carrying results, witnesses, replay identity, and qualifications without strengthening the underlying claim. A frozen differential against the official Cedar 4.12.0 runtime confirmed exact P1 on the declared bounded surface with zero post outcome semantic repair. Separate Linux, SQLite, filesystem, OAuthLib, and Keycloak commissioning exercises test operative effect semantics, prospective route selection, and frozen checker transfer at real action cuts. The empirical claims remain bounded to the reported systems, paths, configurations, and evidence surfaces. The accompanying Consequence Closure Inspector v0.5.0 is archived separately at DOI 10.5281/zenodo.22095595.