Worked on the tapdata/tapdata repository to deliver UI-based primary key management for master-slave merge operations, allowing users to set primary keys directly through the interface. Refactored core merge and error handling logic in Java to improve maintainability and provide clearer, user-facing messages when primary keys or unique indexes are missing, reducing confusion during data integration tasks. Expanded unit testing coverage to address edge cases involving missing keys or indexes, enhancing reliability and preventing regressions. Ensured that all changes aligned with the Tap 5689 commit for functional consistency. The work emphasized backend development, data engineering, and robust error handling practices.