Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
AuthArea: what it touches
Internal ChangesKind: in v2.1.247,
Internal ChangesSection of the release
What
The OAuth device-authorization documentation for third-party server implementors now records that the request body may carry a surface extension parameter, that Claude Code sends surface=claude_code, and that it sends a claude-code user agent on metadata, device, token and refresh requests.
Evidence
surface=claude_code
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Read from
Names in the bundlesurface=claude_code
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeChanged Claude apps gateway sign-in requests to identify Claude Code (a surface=claude_code device-authorization parameter and a…
