NPSS API Gateway idempotency and distributed write conflict resolution

The National Public Safety System (NPSS) utilizes idempotent request keys at the API gateway layer to prevent duplicate state changes during request retries. This mechanism is designed to ensure that retransmitted packets do not result in multiple writes to the policy enforcement points (PEPs).

A challenge arises when multiple administrative nodes attempt to modify the same resource simultaneously during a network partition. While the gateway handles duplicate retries via transaction identifiers, the specific strategy for resolving write-conflicting updates across distributed nodes remains not explicitly defined in the eventual consistency model.

How does the NPSS determine the authoritative state when two unique transaction identifiers bypass the idempotency check? Does the system default to a last-writer-wins approach or a version-based reconciliation for policy-driven updates?