Worked on the temporalio/sdk-python repository to enhance workflow reliability by implementing cancellation of Temporal timers when a workflow.sleep() task is cancelled. Leveraging Python and asynchronous programming, the solution ensures that a TimerCanceled event is explicitly recorded in the workflow history, reducing the risk of orphaned timers in long-running workflows. The approach included comprehensive unit testing to verify correct event recording and improve test coverage. Code readability and maintainability were addressed through linting and refactoring, supporting ongoing workflow management efforts. This work focused on strengthening timer cancellation semantics and improving observability, contributing to a more robust and maintainable codebase.