Post-Gateway-Switchover State Reconciliation: Deterministic Quarantine of Stale and Out-of-Order Messages

This research presents a bounded, deterministic classical software state machine for post-ground-gateway-switchover reconciliation, governed by the frozen Rev 4.2 transition specification. Following gateway recovery or the release of delay/disruption-tolerant networking (DTN) custody, messages may arrive out of order, after expiration, or as duplicate or conflicting copies. The proposed reconciliation model addresses these conditions through deterministic admission rules, sequence tracking, conflict quarantine, authorization checks, and bounded protocol-management journals. Four computational experiment suites (E9–E12) evaluate expired-message rejection, out-of-order supersession, duplicate and conflicting-payload handling, and class-separated state admission. The implementation defines 29 transition labels, with 16 exercised across eight deterministic test schedules. All eight schedules successfully completed their encoded runtime assertions, including checks associated with six candidate safety obligations (C1–C6). The research distinguishes supervisory observations (S), route-metadata views (R), and protocol-management write journals (PROTO_WRITE), while preserving protected-execution boundaries and preventing unauthorized state changes. This work is classified as a software prototype/simulation. It does not establish physical ground-gateway failover, hardware reconfiguration, end-to-end application acceptance, or formally verified mathematical proofs. Physical experiments E1–E6 remain outstanding, while E7–E8 remain outside the manuscript's scope. The Zenodo record includes the research manuscript (PDF) and its corresponding Python 3.9-compatible reference implementation, enabling examination and reproduction of the reported computational experiments.