Filip contributed to the wasp-lang/wasp repository by enhancing authentication user experience and improving build reliability. He developed a configurable authentication UI, allowing distinct submit button labels for login and signup flows in Waspello, which clarified user interactions. Using React and JavaScript, Filip introduced a submitButtonLabel prop to the EmailAndPassForm component, addressing UX clarity in authentication. Additionally, he performed maintenance by purging the package-lock.json file, ensuring deterministic dependency installs and reducing install-time conflicts. His work focused on frontend development and dependency management, resulting in smoother releases and more predictable builds, though the scope was limited to two targeted features.