Dan Sufan Stefka focused on enhancing data quality and reliability in the JustJirka/P6PP repository by developing robust validation for room-related records. He implemented backend logic in C# to enforce business rules, ensuring that room capacities are positive integers and that RoomRequest statuses are valid. Through targeted API development and validation techniques, Dan reduced the risk of invalid data entering the system, thereby minimizing downstream errors and supporting future consistency across modules. His work laid a solid foundation for ongoing data integrity improvements, reflecting a thoughtful approach to backend development and a clear understanding of validation requirements in enterprise applications.