Worked on the DefinitelyTyped/DefinitelyTyped repository to modernize the Apple MapKit JS API type definitions for version 6.0, focusing on enhancing developer experience and compatibility. The update involved migrating asynchronous methods from callback-based patterns to Promise-based flows and adding support for AbortController signals, enabling more robust cancellation and error handling. Leveraging TypeScript and strong API design principles, the work introduced new data-centric interfaces and ensured downstream compatibility by updating related tests. This feature reduced integration friction for TypeScript consumers, allowing for more reliable and maintainable code when working with the latest MapKit JS API surface in JavaScript projects.