Gabriel Leirbag contributed to the bazelbuild/rules_rust repository by improving the reliability of Rust build change detection within Bazel. He addressed a core issue where Bazel previously failed to consistently rebuild Rust crates when manifest or source files changed. By replacing the deprecated repository_ctx.path() with repository_ctx.watch(), Gabriel ensured that changes to Cargo.toml, Cargo.lock, and Rust source files now trigger accurate rebuilds and re-splices. His work involved Starlark scripting and deep familiarity with Bazel’s build system configuration and Rust build tools. This targeted bug fix enhanced the robustness of the build process, reflecting careful attention to evolving Bazel APIs.