Worked on stabilizing UI threading in the AvaloniaUI/Avalonia repository by addressing a race condition in DispatchCore. Focused on ensuring that application.Dispose() executes within a finally block before signaling TaskCompletionSource, which prevented UIThread state leaks during headless test runs. Introduced regression tests to verify Dispatcher.UIThread accessibility immediately after dispatch completion, improving test determinism and reliability in continuous integration environments. Utilized C# and asynchronous programming techniques, applying test-driven development and unit testing practices. The work resulted in more reliable headless CI builds and enhanced maintainability by clarifying the dispatch lifecycle, reducing flaky test scenarios and supporting long-term code stability.