Adds support for MCP servers like StackOverflow that use OAuth but don't
provide standard discovery metadata at .well-known endpoints.
Changes:
- Add fallback OAuth endpoints (/authorize, /token, /register) when
discoverAuthorizationServerMetadata returns undefined
- Add POST fallback in OAuth detection when HEAD returns non-401
(StackOverflow returns 405 for HEAD, 401 for POST)
- Detect OAuth requirement from WWW-Authenticate: Bearer header even
without resource_metadata URL
- Add fallback /token endpoint for token refresh when metadata
discovery fails
- Add registration_endpoint to OAuthMetadata type
This mirrors the MCP SDK's behavior where it gracefully falls back to
default OAuth endpoint paths when .well-known metadata isn't available.
Tests:
- Add unit tests for detectOAuth.ts (POST fallback, Bearer detection)
- Add unit tests for handler.ts (fallback metadata, fallback refresh)
- Add StackOverflow to integration test servers
Fixes OAuth flow for servers that:
- Return 405 for HEAD requests (only support POST)
- Return 401 with simple "Bearer" in WWW-Authenticate
- Don't have .well-known/oauth-authorization-server endpoint
- Use standard /authorize, /token, /register paths
* fix: respect server's token endpoint auth methods for MCP OAuth refresh
Previously, LibreChat always used Basic Auth when refreshing OAuth tokens if a
client_secret was present. This caused issues with servers (like FastMCP) that
only support client_secret_post. Now properly checks and respects the server's
advertised token_endpoint_auth_methods_supported.
Fixes token refresh failures with error: "refresh_token.client_id: Field required"
* chore: remove MCP OAuth URL Logging
