Worked on the PostHog/posthog-js repository to address memory leaks related to same-origin iframes during session recording. Using TypeScript and JavaScript, implemented a comprehensive cleanup mechanism that releases iframe documents and observers when iframes are removed, with robust per-iframe disposer tracking to prevent leaks across mounting and unmounting cycles. Enhanced lifecycle management ensures proper cleanup during pre-load, post-load, and reparenting scenarios, improving stability and performance for long-running sessions on iframe-heavy hosts. The solution was validated with extensive automated tests, confirming correct memory management and safer teardown during recording stop and restart, resulting in reduced memory usage and improved reliability.