pairing_request_expired· reason_code· applies to auth_decision, service_callA `ak.gate.account.command.pair_agent_key.v1` pairing request was presented after its `pairing_expires_at` (or the runtime key-pairing session id has been closed). The endpoint MUST fail closed; the controller MUST initiate a fresh pairing strand. See zh/identity/key-management.md §3.6.2.