Complete a custom MCP setup request

The one-time setup token and the sign-in choice the person made in the browser.

auth_mode is the console dialog's own vocabulary, minus the option this route cannot serve: signing in AT the server is a redirect ceremony and lives on /mcp-setup/oauth/start. What is left is the pair a single request can settle, and stating which one was chosen is what makes the no-credential answer an ANSWER rather than an empty field.

A blank token used to be that answer by accident. min_length=1 admitted a single space, which _resolve_auth then stripped to nothing and recorded as a server needing no credential — so a mistyped paste and a deliberate choice produced the same connection, and neither the person nor the row could tell them apart. A whitespace-only token is now a 422 and the choice has its own field.

The connected account created by a completed setup.