Identity and Access Management for Multi-Region Cognito Clusters

Act as a Cloud Identity Architect. Draft a highly technical strategic blueprint for managing seamless, stateful user identities across multiple, geographically isolated AWS regions utilizing Amazon Cognito. You must architect a robust solution to the notorious [USER_POOL_SYNC_METHOD] challenge, mathematically ensuring that if a user's primary region goes offline, they can seamlessly authenticate against a secondary regional pool without recreating their account or losing profile data. Detail the specific implementation of the [AUTH_FLOW_TYPE] (e.g., SRP vs Custom Auth) and exactly how to securely replicate custom user attributes and Bcrypt password hashes. Explain the architectural necessity of deploying highly customized pre-signup and post-authentication Lambda triggers engineered to continuously synchronize user profiles with a master, globally replicated DynamoDB backend table to guarantee an uncompromising [RELIABILITY_TARGET] of 99.99% uptime.