Harish Rajaselvan focused on enhancing build stability for the FFmpeg/FFmpeg repository by addressing a critical bug affecting ARM64EC Windows builds. He corrected the generation of .def files and improved symbol extraction, ensuring that DLLs are generated correctly and symbol exports remain accurate across ARM64EC and other architectures. His work involved deep system programming and build system expertise, primarily using C and Shell scripting. By validating the fixes through targeted ARM64EC builds and symbol checks, Harish reduced post-release maintenance risks and enabled more reliable packaging for Windows ARM devices, demonstrating thorough attention to cross-architecture compatibility and robust symbol handling.