Worked on the thunderbird/thunderbird-android repository to enhance folder management by implementing a robust account resolution method within the user interface. Focused on ensuring that folder operations consistently use the correct account based on search criteria, the work involved refactoring the account selection logic for improved maintainability and testability. Utilized Kotlin for both the core logic and accompanying unit tests, validating the new behavior and reducing the risk of misrouted folder actions. The changes addressed a key user experience issue and were encapsulated in a single feature commit, demonstrating a methodical approach to Android development and quality assurance through unit testing.