During January 2026, Keqing Rong focused on improving API error handling in the DefinitelyTyped/DefinitelyTyped repository. They addressed ambiguity in the checkJsApi method by updating its type definition, changing the errMsg parameter from an object to a string. This adjustment clarified error messages and aligned the type definitions with actual runtime behavior. Keqing Rong also updated the related test suite to ensure the new type was properly validated and that the API surface remained stable. Their work demonstrated a strong grasp of TypeScript, type definitions, and API development, contributing to a more predictable and developer-friendly experience for consumers.