Worked on enhancing the reliability of the ShipEngine/shipengine-dotnet SDK by addressing a critical issue in the WaitAndRetry timeout logic. Focused on correcting the handling of timeouts longer than 60 seconds by switching from TimeSpan.Seconds to TotalSeconds and TotalMilliseconds, ensuring accurate retry behavior for long-running operations. Added comprehensive regression tests to cover edge cases and prevent future issues in the retry mechanism. Updated the SDK version to deliver the fix to downstream clients. Utilized C# for SDK development, emphasizing robust error handling and thorough unit testing to maintain high standards of code quality and operational reliability.