During July 2025, Matthias Eichner focused on backend development for the MyCoRe-Org/mir repository, addressing a critical bug related to permission checks for displaying derivates. He replaced the existing acl:checkPermissionForReadingDerivate logic with acl:checkDerivateDisplayPermission, ensuring that permission evaluation aligned with security requirements and prevented unauthorized access or display errors. Working primarily with XSLT and leveraging his expertise in ACL-based permission handling, Matthias delivered a targeted, traceable fix that stabilized the permission model. Although no new features were released, his work improved the reliability and security of derivate display, demonstrating depth in backend workflows and precise bug resolution.