Phase A needed a token pasted into a header, which Anthropic documents as an
org-admin-scoped beta on claude.ai and is undocumented on ChatGPT. This makes
the app its own authorization server so both connect through their normal
"add a connector" flow, with a per-user consent screen.
The whole thing funnels into the existing verifyMcpToken: an issued access
token is an ordinary McpAccessToken row with source "oauth", so the resource
server gained no OAuth awareness and Phase A's verification path is unchanged.
Notes on the parts that fail quietly if got wrong:
- scopes_supported is published in the protected resource metadata. When a 401
challenge carries no explicit scope Claude requests exactly what is
advertised there, so omitting it silently makes every connection read-only.
- Loopback redirect URIs match with the port ignored. Claude Code registers
http://localhost/callback and then redirects to an ephemeral port; exact
matching would reject every native client. RFC 8252 7.3 requires this.
- CIMD is deliberately not advertised. Claude only selects it when the metadata
carries client_id_metadata_document_supported, and supporting it would mean
fetching a client-supplied URL server-side from a host that also reaches
MinIO, Postgres and the gateway on the LAN. DCR costs nothing by comparison.
- The consent page validates client_id and redirect_uri before it will redirect
anywhere, because an unvalidated redirect_uri is an open redirect.
- Authorization codes are consumed by one guarded updateMany, so a replay under
concurrency cannot mint a second token. A PKCE mismatch burns the whole grant
rather than just the code.
- Refresh tokens rotate and keep the previous hash; presenting it revokes the
grant, since that is either theft or a client that cannot be trusted to hold
state.
Also fixes the login page, which hardcoded callbackUrl and so dropped anyone
sent to sign in for the consent screen onto /dashboard instead. Same-origin
destinations only, absolute or relative - the middleware writes absolute.
"/.well-known" joins PUBLIC_ROUTES. It is a prefix match, so nothing else
should be served from there.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W1Ee4Mc1X1SX8HgYa52zu7
