Marcin Roman contributed to the mmoayyed/cas repository by enhancing the modularity and maintainability of authentication flows, focusing on WebAuthn and Google MFA. He introduced a distinct webflow state for saving WebAuthn registrations, separating it from the existing saveRegistration state to decouple concerns and simplify future refactoring. Additionally, he clarified the Google Authenticator registration process by renaming its state for improved code readability. Working primarily with Java and leveraging backend development and Webflow configuration skills, Marcin’s changes aimed to reduce maintenance costs, streamline onboarding for new engineers, and minimize the risk of cross-component bugs in the authentication system.