Worked on the aws/aws-cdk-cli repository to address reliability and performance issues in the AWS CDK CLI, focusing on backend development with Node.js and TypeScript. Delivered a targeted fix for a garbage collection hang by introducing a 'stopped' flag within the BackgroundStackRefresh component, ensuring that refresh operations are not rescheduled if stop() is invoked during an in-flight refresh. Added a regression test to safeguard against this scenario, maintaining API compatibility and preserving existing behavior. This work eliminated silent hangs that previously caused CI timeouts in long-running pipelines, improving the stability and reliability of production workflows without altering public interfaces.