Worked on the rust-lang/cargo repository to enhance build stability by addressing a regression related to the --artifact-dir flag on the stable channel. Developed and integrated a targeted regression test in Rust to ensure this flag is properly rejected, preventing potential user-facing issues and reinforcing the reliability of Cargo’s stable releases. Applied code formatting improvements using rustfmt, which increased the readability and maintainability of the test suite. Focused on testing and code formatting as core skills, the work facilitated future contributions by making the codebase clearer and more robust, though the scope was limited to bug fixing rather than feature development.