During May 2025, Alfonso focused on strengthening authentication reliability in the ogcio/shared-node-utils repository. He addressed concurrency issues in backend token management by implementing mutex-based serialization for Logto token requests using TypeScript. This approach ensured that only one token refresh could occur at a time, eliminating invalid grant errors caused by concurrent requests and making token retrieval deterministic. Alfonso also developed comprehensive unit tests to validate mutex behavior under concurrent conditions, demonstrating a strong emphasis on testing and concurrency control. His work improved the predictability and robustness of authentication flows, reflecting thoughtful engineering depth within a focused, high-impact bug fix.