During June 2025, Arnaud Sevin focused on improving build stability and data handling reliability for the spacetelescope/catkit2 repository. He addressed a compilation-time bug by adding the missing cstdint include to the FitsFile.h header, ensuring proper definition of fixed-width integer types such as uint64_t. This change enhanced cross-platform compatibility and reduced potential build failures, supporting smoother CI and release processes. Working primarily with C++ and header file management, Arnaud’s efforts centered on code quality and portability rather than new features. The work demonstrated careful attention to core infrastructure, resulting in more robust Fits I/O data handling across environments.