agent_key_authorization_expired· reason_code· applies to auth_decisionAgent session issuance rejected because the referenced ak.agent.key.authorize declared an expires_at that has elapsed. Distinct from proof_invalid (malformed / unverifiable proof): the runtime should prompt the controller to re-authorize the same key (same-key re-authorization, zh/identity/key-management.md §3.6) rather than rebuild the proof. Never returned for non-expiring (absent expires_at) authorizations.