Worked on the cloudnativedaysjp/dreamkast repository to implement and standardize cross-origin resource sharing (CORS) for emtec.tv, enabling secure cross-origin requests and streamlining frontend integration. Focused on backend development using Ruby on Rails, the work involved creating a consistent CORS configuration across all environments to reduce configuration drift and simplify future enhancements. Refactored the CORS setup for improved readability and maintainability, including adjustments to syntax and method array handling. The changes consolidated CORS-related logic, introduced an allow-list for emtec.tv domains, and established a uniform policy throughout the codebase, laying groundwork for easier maintenance and enhanced security in future updates.