Worked on stabilizing Linux-user UID handling in the espressif/qemu repository by addressing a build issue with the uid_wrapper library. Introduced direct syscall wrappers for setreuid and setregid, aligning them with existing setuid and setgid wrappers to ensure consistent and reliable user ID transitions. This low-level programming effort, implemented in C, improved build reliability and continuous integration stability for downstream users. The work focused on kernel development and system programming, reducing maintenance overhead and enhancing cross-platform compatibility. By refining the UID transition paths, the developer contributed to a more robust and maintainable codebase for Linux-user environments.