fix(mcp): Fix discover_tools test mock and credential auto-unselect

- Add missing `refresh_if_needed` mock to test_discover_tools_auto_uses_stored_credential
  so it returns the stored credential instead of a MagicMock
- Fix credential auto-unselect clearing MCP credentials on initial render:
  skip the "unselect if not available" check when the saved credentials
  list is empty (empty list means not loaded yet, not invalid)

autogpt_platform/backend/backend/api/features/mcp/test_routes.py

@@ -108,6 +108,7 @@ class TestDiscoverTools:
             patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
         ):
             mock_cm.store.get_creds_by_provider = AsyncMock(return_value=[stored_cred])
+            mock_cm.refresh_if_needed = AsyncMock(return_value=stored_cred)
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 return_value={"serverInfo": {}, "protocolVersion": "2025-03-26"}

autogpt_platform/frontend/src/components/contextual/CredentialsInput/useCredentialsInput.ts

@@ -88,11 +88,14 @@ export function useCredentialsInput({
     }
   }, [credentials, onLoaded]);
 
-  // Unselect credential if not available
+  // Unselect credential if not available in the loaded credential list.
+  // Skip when no credentials have been loaded yet (empty list could mean
+  // the provider data hasn't finished loading, not that the credential is invalid).
   useEffect(() => {
     if (readOnly) return;
     if (!credentials || !("savedCredentials" in credentials)) return;
     const availableCreds = credentials.savedCredentials;
+    if (availableCreds.length === 0) return;
     if (
       selectedCredential &&
       !availableCreds.some((c) => c.id === selectedCredential.id)