Worked on stabilizing tag management in the tolgee/tolgee-platform repository, focusing on resolving concurrency issues during complex tag updates. Addressed a ConcurrentModificationException in the updateTags flow by restructuring the logic to separate the collection and removal of tags, ensuring safe operations under concurrent conditions. Enhanced the backend using Kotlin and the Spring Framework, and introduced automated regression tests to verify correct tag removals and updates. This approach improved the reliability and maintainability of the tagging workflow, reducing the risk of future regressions and incorrect tag handling. The work emphasized robust concurrency handling and comprehensive test coverage for backend stability.