🛂 refactor: Use discoverAuthorizationServerMetadata for MCP OAuth (danny-avila#8723)

* Use discoverAuthorizationServerMetadata instead of discoverMetadata

Uses the discoverAuthorizationServerMetadata function from the upstream
TS SDK. This has the advantage of falling back to OIDC discovery
metadata if the OAuth discovery metadata doesn't exist which is the case
with e.g. keycloak.

* chore: import order

---------

Co-authored-by: Danny Avila <danacordially@gmail.com>

Author: jhrozek

packages/api/src/mcp/oauth/handler.ts

@@ -1,10 +1,10 @@
 import { randomBytes } from 'crypto';
 import { logger } from '@librechat/data-schemas';
 import {
-  discoverOAuthMetadata,
   registerClient,
   startAuthorization,
   exchangeAuthorization,
+  discoverAuthorizationServerMetadata,
   discoverOAuthProtectedResourceMetadata,
 } from '@modelcontextprotocol/sdk/client/auth.js';
 import { OAuthMetadataSchema } from '@modelcontextprotocol/sdk/shared/auth.js';
@@ -61,7 +61,7 @@ export class MCPOAuthHandler {
 
     // Discover OAuth metadata
     logger.debug(`[MCPOAuth] Discovering OAuth metadata from ${authServerUrl}`);
-    const rawMetadata = await discoverOAuthMetadata(authServerUrl);
+    const rawMetadata = await discoverAuthorizationServerMetadata(authServerUrl);
 
     if (!rawMetadata) {
       logger.error(`[MCPOAuth] Failed to discover OAuth metadata from ${authServerUrl}`);
@@ -466,7 +466,10 @@ export class MCPOAuthHandler {
           throw new Error('No token URL available for refresh');
         } else {
           /** Auto-discover OAuth configuration for refresh */
-          const { metadata: oauthMetadata } = await this.discoverMetadata(metadata.serverUrl);
+          const oauthMetadata = await discoverAuthorizationServerMetadata(metadata.serverUrl);
+          if (!oauthMetadata) {
+            throw new Error('Failed to discover OAuth metadata for token refresh');
+          }
           if (!oauthMetadata.token_endpoint) {
             throw new Error('No token endpoint found in OAuth metadata');
           }
@@ -584,7 +587,7 @@ export class MCPOAuthHandler {
       }
 
       /** Auto-discover OAuth configuration for refresh */
-      const { metadata: oauthMetadata } = await this.discoverMetadata(metadata.serverUrl);
+      const oauthMetadata = await discoverAuthorizationServerMetadata(metadata.serverUrl);
 
       if (!oauthMetadata.token_endpoint) {
         throw new Error('No token endpoint found in OAuth metadata');