DAG Closure and Acyclicity by Construction in Canonically Referenced MCIR Systems

This note formalizes a precise structural property of canonically referenced MCIR systems. If every immutable artifact version may reference only strictly earlier immutable versions, then the resulting reference graph is acyclic by construction. If admission also checks local schema and every outgoing reference against declared identity, type, scope, authority, and version constraints, then admitted graph state is structurally closed under those checks. The result is strong but narrower than universal correctness. It does not prove truth, semantic adequacy, policy justice, validator correctness, provenance, replayability, or continued validity after authority revocation or policy change. Canonical identity alone is insufficient if a target can mutate beneath the same identifier. Receipts and content/state bindings are required for custody; revalidation and invalidation propagation are required when governing assumptions change. This revision preserves the acyclicity proof, replaces the tautological phrase "global correctness" with referential structural closure, specifies versioned construction, distinguishes acceptance evidence from truth, integrates the result with constraint-bearing composition, semantic custody, receipts, the Governed Meaning Base (GMB), and the universal GSM, and supplies counterexamples and an evaluation program.