Worked on enhancing federation interoperability and security within the Automattic/wordpress-activitypub repository, focusing on API and backend development using PHP. Delivered a feature that improved signature verification compatibility with Mastodon by ensuring the query string was included in the request-target, addressing the requirements of peers that validate the full request-target. Developed comprehensive unit tests to cover signed GET requests both with and without query strings, validating the accuracy of the signature reconstruction logic. These targeted changes to the HTTP Signature verification flow reduced the risk of cross-peer signature rejection and contributed to more reliable and secure federation across compatible platforms.