During April 2025, Xbjfk focused on improving the reliability of memory-mapped file operations in the RustPython/RustPython repository. Addressing a critical issue where mmap would abort in debug mode when provided with an invalid file descriptor, Xbjfk implemented a targeted fix using Unix APIs and system programming techniques. By integrating fstat to retrieve file metadata before mapping, the solution prevented file descriptor-related errors and enhanced the robustness of file I/O paths. Working primarily in C and Rust, Xbjfk’s contribution deepened the project’s resilience against edge cases, ensuring more predictable behavior for developers working with memory mapping in RustPython.