Worked on the dotnet/orleans repository to enhance backend stability by addressing a critical issue in the ActivationCollector component. Focused on resolving an ArgumentException that could arise when cancelling an indefinite keep-alive, the developer implemented a targeted fix and expanded unit test coverage to safeguard against regressions in complex edge cases. Using C# and leveraging strong backend development and unit testing skills, they ensured that cancellation logic now handles scenarios where the collection ticket is set to DateTime.MaxValue without error. The work improved runtime resilience and reliability, emphasizing careful validation and robust test-driven development practices throughout the process.