Worked on the OpenCTI backend repository, focusing on improving the stability and reliability of the subscription system. Addressed a critical issue where null payloads could create orphaned Redis subscriptions by implementing backend guards and enforcing validation of required fields before processing subscription payloads. This approach prevented potential data leaks and inconsistent application states, directly enhancing the reliability of real-time subscriptions. The work involved backend development using TypeScript, with a strong emphasis on integrating GraphQL and Redis to ensure robust data flow and error handling. The contribution centered on bug fixing, prioritizing system integrity and runtime error reduction over new feature development.