During February 2026, Wheerd focused on enhancing type safety within the pmndrs/zustand repository by improving the Immer middleware. He introduced a generic type parameter to the middleware, enabling better compatibility with sliced stores and reducing type-related errors in client code. His approach involved clarifying type definitions and implementing comprehensive tests to validate typing across different slice types, ensuring robust type safety for large-scale TypeScript applications. By maintaining rigorous test coverage and refining developer experience, Wheerd demonstrated depth in middleware development and type safety, leveraging TypeScript to deliver maintainable, future-proof improvements that streamline usage and integration for other developers.