Add support for Client ID Metadata Documents to enable URL-based client registration (#1023)

src/ModelContextProtocol.Core/Authentication/ClientOAuthOptions.cs

@@ -23,6 +23,17 @@ public sealed class ClientOAuthOptions
     /// </remarks>
     public string? ClientSecret { get; set; }
 
+    /// <summary>
+    /// Gets or sets the HTTPS URL pointing to this client's metadata document.
+    /// </summary>
+    /// <remarks>
+    /// When specified, and when the authorization server metadata reports
+    /// <c>client_id_metadata_document_supported = true</c>, the OAuth client will respond to
+    /// challenges by sending this URL as the client identifier instead of performing dynamic
+    /// client registration.
+    /// </remarks>
+    public Uri? ClientMetadataDocumentUri { get; set; }
+
     /// <summary>
     /// Gets or sets the OAuth scopes to request.
     /// </summary>