Worked on the City-of-Helsinki/yjdh repository to restructure the Kesäseteli development environment, focusing on improving local development speed and onboarding processes. Refactored Docker Compose configurations to separate base, employer, and handler services, introducing distinct development and production targets and enhancing compatibility with Linux and WSL. Enhanced onboarding by reorganizing the README in Markdown, adding a table of contents, detailed service environment information, and expanded setup and troubleshooting sections. Leveraged DevOps practices, Docker, and Yarn to streamline maintenance and reduce setup errors, resulting in a more maintainable codebase and smoother contributor handovers for both backend and frontend development.