Worked on backend stability for the infiniflow/ragflow repository, focusing on the Session Listing endpoint. Addressed a critical crash by implementing strict type validation to ensure only dictionary objects were processed, which prevented AttributeError and improved endpoint reliability. Used Python to enhance data validation and applied defensive programming techniques, resulting in more robust error handling and maintainable code. The targeted fix was delivered with clear commit traceability, directly reducing error rates and strengthening downstream analytics. This work demonstrated proficiency in API development and backend engineering, emphasizing type safety and code hygiene to improve user trust and the overall stability of session listings.