Worked on the Max-Eee/E-commerce-recommender repository to address a checkout data integrity issue by implementing billing address phone number validation and autofill. Focused on improving the reliability of the checkout process, the solution required adding a mandatory phone number field to the billing address form and integrating frontend validation using React and TypeScript. The autofill feature leveraged existing customer data to pre-populate the phone number when available, reducing manual entry and potential support requests. This targeted bug fix ensured that all billing information was complete before order submission, enhancing both user experience and data consistency within the e-commerce platform.