Worked on the firebase/firebase-ios-sdk repository to enhance authentication token management by developing a Token Refresh Coalescing Mechanism. This feature ensures that concurrent token refresh requests are handled by a single network call, reducing redundant traffic and improving network efficiency. The implementation focused on concurrency management and was written in Swift, with comprehensive unit and integration tests added to validate both correctness and performance. By addressing concurrency safety and optimizing network usage, the work contributed to a more robust token lifecycle for iOS applications, demonstrating a methodical approach to improving SDK reliability through targeted feature development and thorough testing practices.