media_service_binding_uncovered· reason_code· applies to service_call, state_resolutionA media token / focus join was presented but the current MLS epoch governance binding does not cover the `ak.realm.media_service` binding the token relies on (token issuer trust-root sealing is unverifiable). The verifier MUST fail closed instead of trusting an uncovered media binding. See zh/crypto-media/media-service-binding.md §2.1.