Worked on the rerun-io/rerun repository to enhance build system reliability by implementing a deterministic dependency fetch for Arrow C++ using CMake. The approach replaced Git-based cloning with a tarball download, validated by an MD5 checksum, to ensure stable and reproducible builds. By disabling download progress reporting, the build output became cleaner and easier to interpret, which streamlined continuous integration diagnostics. This work focused on build system configuration and dependency management, reducing build variance and simplifying maintenance. The changes improved both reproducibility and clarity in the build process, leveraging CMake and shell scripting to deliver more predictable CI outcomes.