fix(frontend/credentials): Auto-select user credentials in run dialog

Add auto-selection for user credentials (like MCP OAuth) in the
CredentialsGroupedView run dialog. When exactly one credential matches
the provider, type, and discriminator values (e.g. MCP server URL),
it is pre-selected instead of defaulting to "None (skip this credential)".

autogpt_platform/frontend/src/components/contextual/CredentialsInput/components/CredentialsGroupedView/CredentialsGroupedView.tsx

@@ -16,6 +16,7 @@ import {
   areSystemCredentialProvidersLoading,
   CredentialField,
   findSavedCredentialByProviderAndType,
+  findSavedUserCredentialByProviderAndType,
   hasMissingRequiredSystemCredentials,
   splitCredentialFieldsBySystem,
 } from "./helpers";
@@ -45,6 +46,7 @@ export function CredentialsGroupedView({
   const hasSystemCredentials = systemCredentialFields.length > 0;
   const hasUserCredentials = userCredentialFields.length > 0;
   const hasAttemptedAutoSelect = useRef(false);
+  const hasAttemptedUserAutoSelect = useRef(false);
 
   const isLoadingProviders = useMemo(
     () =>
@@ -111,6 +113,49 @@ export function CredentialsGroupedView({
     isLoadingProviders,
   ]);
 
+  // Auto-select user credentials when there is exactly one matching credential.
+  // This handles cases like MCP where the credential is optional but should
+  // still be pre-selected when only one credential matches the server URL.
+  useEffect(() => {
+    if (hasAttemptedUserAutoSelect.current) return;
+    if (!hasUserCredentials) return;
+    if (!allProviders) return;
+
+    for (const [key, schema] of userCredentialFields) {
+      const alreadySelected = inputCredentials?.[key];
+      if (alreadySelected) continue;
+
+      const providerNames = schema.credentials_provider || [];
+      const credentialTypes = schema.credentials_types || [];
+      const requiredScopes = schema.credentials_scopes;
+      const discriminatorValues = schema.discriminator_values;
+      const savedCredential = findSavedUserCredentialByProviderAndType(
+        providerNames,
+        credentialTypes,
+        requiredScopes,
+        allProviders,
+        discriminatorValues,
+      );
+
+      if (savedCredential) {
+        onCredentialChange(key, {
+          id: savedCredential.id,
+          provider: savedCredential.provider,
+          type: savedCredential.type as CredentialsType,
+          title: savedCredential.title,
+        });
+      }
+    }
+
+    hasAttemptedUserAutoSelect.current = true;
+  }, [
+    allProviders,
+    hasUserCredentials,
+    userCredentialFields,
+    inputCredentials,
+    onCredentialChange,
+  ]);
+
   return (
     <div className="space-y-6">
       {hasUserCredentials && (