Worked on the Adyen/adyen-magento2 repository to resolve a critical issue in the Magento 2 payment integration, focusing on backend development and API integration using PHP. Addressed a bug where multiple orders could exist for the same quote by implementing logic to always select the most recent order for payment processing, achieved by sorting orders by entity ID in descending order and limiting the result to one. Enhanced the reliability of the checkout process and reduced the risk of incorrect payments. Updated unit tests for both the OrderRepository and Sort Order Builder, improving test coverage and supporting test-driven development practices.