Worked on the rolldown/rolldown repository to modernize the watcher process, focusing on improving reliability and simplifying runtime behavior. The approach involved replacing the legacy watcher worker, which relied on an infinite loop, with a timer-based solution to prevent premature main process exit while maintaining existing functionality. This change eliminated watcher-worker.js, reducing thread overhead and streamlining lifecycle management. The work was implemented using JavaScript, TypeScript, and Node.js, leveraging system programming and build tool expertise. The result was a cleaner, more maintainable codebase that preserved feature parity and improved the reliability of the watcher process without introducing new bugs.