High-Availability Messaging with Multi-Region SQS and SNS

Act as a Distributed Messaging Architect. Design an indestructible, highly resilient asynchronous messaging backbone utilizing Amazon SQS and SNS spanning multiple geographically isolated AWS regions. The system must effortlessly absorb a massive [MESSAGE_THROUGHPUT] load (e.g., 50,000 TPS) while strictly adhering to the specified [ORDERING_REQUIREMENTS] (e.g., strict FIFO sequencing versus high-throughput Standard queuing). Implement a highly complex, cross-region [FANOUT_PATTERN] where events published to an SNS topic in the primary region are reliably broadcasted and consumed by isolated SQS queues residing in multiple secondary regions. Detail the architectural implementation of the 'failover queue' pattern to intercept dropped messages during a regional API partition. Provide the mathematical logic required within the consumer Lambda functions to guarantee idempotency and safely process duplicate payloads generated by the 'at-least-once' delivery nature of cross-region SNS.