Worked on improving module resolution stability in the vitest-dev/vitest repository by addressing compatibility issues with CommonJS modules in modern Node.js environments. Implemented a targeted fix that filters out the 'module-sync' condition during module resolution, preventing loader errors on Node.js versions that natively support this feature. Enhanced the reliability of continuous integration pipelines and reduced runtime failures for downstream projects by adding regression tests to validate the change. Utilized JavaScript, TypeScript, and Node.js to ensure robust testing and compatibility. The work focused on maintaining stability and broadening support for evolving Node runtimes without introducing new features during the period.