bridge

MB3 Bearer import

Lean spine source

Declarations: MB3_bearer_import

From the machine-checked spine in formal/ (Mathlib + spine imports). Not self-contained for Lean 4 Web — use the repo or a local lake build.

axiom MB3_bearer_import :
  ∀ A B : System, BundleTransport A → SameBearerMap A B → BearerTransport B

/-- MB4: correction legitimacy. Correction-channel integrity requires that the
    judge is not manipulated in a way that invalidates later endorsement. -/