During November 2025, Deroulers contributed to the MilesCranmer/julia repository by addressing a persistent issue in the Julia build process related to temporary file cleanup. Leveraging backend development and system programming skills in Julia, Deroulers modified the build system to disable automatic cleanup during temporary file creation, instead delegating cleanup responsibilities to the temporary directory mechanism. This approach resolved a class of infinite error loops caused by leftover temporary files, resulting in more stable and efficient CI cycles. The work demonstrated a thoughtful understanding of build system internals and improved both maintainability and reliability for developers working with the Julia codebase.