fix(core): prevent MCP tool wiping on background discovery failures

packages/core/src/tools/mcp-client.test.ts

@@ -1461,8 +1461,8 @@ describe('mcp-client', () => {
       // Trigger notification - should fail internally but catch the error
       await notificationCallback();
 
-      // Should try to remove tools
-      expect(mockedToolRegistry.removeMcpToolsByServer).toHaveBeenCalled();
+      // Should NOT try to remove tools when discovery fails
+      expect(mockedToolRegistry.removeMcpToolsByServer).not.toHaveBeenCalled();
 
       // Should NOT emit success feedback
       expect(coreEvents.emitFeedback).not.toHaveBeenCalledWith(

packages/core/src/tools/mcp-client.ts

@@ -1344,6 +1344,7 @@ export async function discoverTools(
         error,
         mcpServerName,
       );
+      throw error;
     }
     return [];
   }