Worked on the facebook/pyrefly repository to improve cross-platform build hygiene by addressing Windows-specific build issues in Rust. Focused on system programming, the developer implemented gating for jemalloc statistics in pyrefly_util, ensuring that allocator-stats are not built on Windows targets. This approach reduced unnecessary dependencies and streamlined the Windows build process for downstream consumers. The work included upstream improvements and preparation for removing the Windows overlay, which enhances CI reliability and simplifies future maintenance. Collaboration with reviewers ensured smooth integration, and the changes preserved full functionality on non-Windows platforms while improving reliability and performance for Windows users.