Worked on the TanStack/query repository to address a type inference issue affecting the setQueryData updater, specifically when the updater function declared an explicit return type. Focused on enhancing type safety and developer experience, the solution ensured correct data parameter inference across both query-core and vue-query packages. The approach involved targeted TypeScript changes with minimal impact on the overall codebase, accompanied by comprehensive unit tests to verify correctness and prevent regressions. This work improved cross-package compatibility and reliability for frontend developers, demonstrating a strong command of frontend development, type inference, and unit testing within a modern TypeScript codebase.