Extracting a stateful service from a monolithic architecture involves carefully separating reads and writes, creating formal interfaces, and synchronizing data handling to facilitate a controlled migration to an external service. The process requires strategies such as using facades, update duplicators, and feature flag toggles to manage the transition and maintain system integrity. The article illustrates the complexity of this task with the example of extracting a Product Catalog from an e-commerce system, emphasizing the challenge of replacing database-level integrations with formal service integrations. A key strategy is to segregate querying and updating states, allowing for a phased migration while maintaining data consistency across both the monolith and the new service. The narrative underscores the critical importance of minimizing time in transitional states to prevent data inconsistency and potential corruption, advocating for precise planning and execution to ensure a successful architectural shift.