Worked on the all-of-us/workbench repository to refine the user credit reprocessing and expiration handling workflow, focusing on backend logic in Java. Developed and implemented a guard to prevent reprocessing of credits for expired users, then carefully rolled back this change to accommodate updated expiration policies, demonstrating disciplined change management and risk assessment. Maintained codebase stability by ensuring no lasting behavioral changes and thoroughly documenting the rationale for each iteration. Collaborated with the team to evaluate user lifecycle edge cases, laying the groundwork for future expiration-rule enhancements. Emphasized unit testing and clear communication throughout the development and review process.