Sebastian upgraded the CKEditor 5 integration in the neos/neos-ui repository, moving from version 16.0.0 to 44.0.0 to enhance editing capabilities and streamline developer workflows. He adapted the application’s JavaScript and CSS code to ensure compatibility with the new editor APIs and updated various plugins to align with the latest CKEditor ecosystem. Sebastian also revised and stabilized end-to-end tests using TestCafe, improving test reliability and continuous integration feedback. This work delivered a more robust and feature-rich editing experience, reflecting a focused, in-depth approach to frontend development and codebase modernization within a short project timeframe.