Worked on the google/site-kit-wp repository to deliver targeted PHP 8.1 compatibility improvements and enhance backend reliability. Addressed dynamic namespace patching by refining the phpscoper patcher, updating the namespace regex to robustly handle fully qualified class names and various escaping forms. Expanded test coverage with a new unit test for BigInteger engine resolution, guarding against regression from scoped namespace patching issues. Fixed property access in TestCase classes to align with PHP 8.1’s handling of private properties, reducing maintenance overhead. Utilized PHP, reflection, and regex to ensure stable upgrades and improve production reliability through careful backend development and comprehensive testing.