Worked on the TanStack/virtual repository to address a complex edge case in virtualization logic, specifically correcting the total size calculation when a single item spans multiple lanes. Applied strong debugging skills to adjust loop conditions, preventing negative or zero indices and ensuring accurate total size computation. Enhanced the reliability and user experience of multi-lane layouts by adding targeted unit and integration tests that validate the new behavior. Utilized JavaScript and TypeScript for both the fix and the accompanying tests, demonstrating a disciplined approach to frontend development and testing. This work improved the stability and correctness of core virtualization math in the project.