Worked on stabilizing and modernizing testing and development infrastructure across goldbergyoni/vitest and platformatic/platformatic repositories. Improved test reliability in vitest by upgrading the @sinonjs/fake-timers dependency, refining timer exposure, and enhancing error handling to reduce flaky tests and accelerate CI feedback. In platformatic, delivered a TypeScript syntax modernization, replacing deprecated module syntax with namespace to align with current standards and improve maintainability. Addressed a bug affecting custom environment file loading on development server restarts, ensuring dynamic configuration and adding test coverage. Utilized JavaScript, TypeScript, and Node.js, focusing on dependency management, software maintenance, and robust testing practices throughout the work.