Worked on stabilizing the renderer for the thinking-machines-lab/tinker-cookbook repository, focusing on backend development and robust edge-case handling using Python. Addressed a regression that caused the renderer to crash when no user messages were present, implementing a targeted fix to ensure graceful handling of empty input scenarios. Developed and integrated regression tests to validate correct token weight assignment and prevent similar issues from recurring. This work improved runtime stability, enhanced test coverage, and reduced the risk of production crashes. The efforts laid a foundation for future improvements in renderer resilience, emphasizing maintainability and reliability through careful testing and backend engineering.