Chenchang Wang contributed to the ucsb-cs156/proj-courses repository by delivering two core features focused on scalability and user experience. He enabled multi-user concurrency for the H2 database, tuning its properties to support simultaneous connections and improve backend reliability for coursework management. On the front end, he refactored the SectionsTable component using React and JavaScript, integrating backend mutation logic to provide clearer error handling and success messaging. Additionally, he improved code maintainability by removing unnecessary ESLint exceptions and standardizing backend mutation patterns. His work demonstrated depth in both Java and front end development, addressing real-world multi-user application needs.