Worked on the TanStack/router repository to enhance the stability and reliability of the hydration flow, focusing on a critical bug fix rather than new feature development. Addressed a race condition in the deferred loader that previously allowed the resolvePromise tsr-once script to be deleted before execution, which could cause runtime errors during server-side and client-side rendering transitions. Utilized advanced debugging techniques in asynchronous JavaScript and TypeScript code paths, applying expertise in React and front end development. The work improved script execution consistency, ensured proper resource cleanup, and laid a stronger foundation for future feature velocity and platform reliability within the codebase.