Developed a configurable registration flow for the element-hq/synapse repository, introducing an option to control whether user registrations can begin with an underscore. This feature addressed the need to balance internal AppServices safety with external onboarding flexibility by allowing administrators to toggle underscore-prefixed registrations. The implementation involved backend development using Python and YAML, with comprehensive updates to documentation and the addition of targeted tests to ensure reliable behavior. By focusing on configuration management and user management, the work improved the system’s adaptability and governance around registrations, while maintaining safe defaults and providing clear traceability through well-documented code changes.