HTTP servers without an Authorization header sign in with OAuth: stored
tokens in mcp-auth.json, refreshed without a browser. /mcp/sign-in/<server>
returns to a loopback callback when the browser runs on the p2 host (the
device owner, or a relayed/public owner whose browser reaches a nonce probe
on 127.0.0.1), else to /mcp/callback on the origin p2 is reached through.
Pasting the final redirect URL always completes a waiting sign-in.
Web: an MCP sheet (status, restart, sign in/out, paste). TUI: /mcp and
/mcp paste. The sidebar footer's owner entries move into a More menu.