You'll notice
MCP OAuth redirect URI checks now normalize 127.0.0.1 and localhost as equivalent loopback addresses
What
When Claude Code validates the redirect URI (the address a login flow sends you back to) for an MCP server's OAuth login, it now recognizes 127.0.0.1 and localhost as equivalent loopback addresses. New helper logic normalizes one to the other before comparing, and extracts the port number for later use.
Why
Some OAuth providers or local servers may use 127.0.0.1 while others use localhost for the same local address; treating them as equivalent avoids OAuth login failing due to this mismatch.