Worked on the picnixz/cpython repository to clarify and document the correct usage of the ob_mutex member in CPython’s free-threaded builds. Focused on reducing deadlock risks by updating API references and providing explicit guidance for extension authors, recommending the use of a separate PyMutex field for custom locks. Collaborated with core maintainers to ensure documentation consistency and accuracy, aligning with Python’s evolving concurrency model. Utilized C and Python to update documentation and cross-link critical section APIs, improving maintainability and onboarding for new contributors. The work emphasized best practices in API design, documentation, and safe concurrency patterns for Python extension development.