Worked on the jlowin/fastmcp repository to deliver RFC 8252-compliant OAuth Redirect URI validation, focusing on loopback redirect URI port matching when the port is unspecified. This backend improvement, implemented in Python, tightened redirect URI matching logic to prevent misrouting and enhance OAuth security. The update addressed a key integration pain point by ensuring consistent redirect behavior across local development, CI, and staging environments, thereby reducing support issues related to misconfigured URIs. The work involved careful API development, backend validation, and thorough testing, culminating in a focused patch that improved both security and interoperability for enterprise OAuth deployments.