Worked on the rescript-lang/rescript repository to enhance the build pipeline by introducing concurrency-safe mechanisms for parallel builds under file watchers. Developed a locking system using lockfiles to coordinate build and watch processes, ensuring robust lifecycle management with automatic cleanup and handling of edge cases such as disappearing paths. Extended the approach to support branch-specific lockfiles and refined messaging for better clarity during build operations. Comprehensive test coverage was added to validate concurrency paths and failure scenarios, reducing the risk of regressions. The work was implemented in Rust, leveraging backend development and concurrent programming skills to improve build reliability and speed.