feat(AgentManager): improve pickling for _performance_metrics and add GPU guard

Enhance custom pickling to safely serialize _performance_metrics by converting non-serializable objects to strings and ensure proper initialization on unpickling. Also guard the HuggingFace Spaces GPU decorator with ENABLE_GPU env var.

app.py

@@ -226,15 +226,35 @@ class AgentManager:
         logger.info("Agent manager initialized (agents will be created lazily)")
         
         def __getstate__(self):
-            """Custom pickling to handle non-serializable objects."""
-            state = self.__dict__.copy()
-            # Remove any non-serializable objects if they exist
-            return state
+        """Custom pickling to handle non-serializable objects."""
+        state = self.__dict__.copy()
+        # Remove any non-serializable objects if they exist
+        # Remove performance metrics that might contain non-serializable objects
+        if '_performance_metrics' in state:
+            # Create a copy without thread-locked objects
+            safe_metrics = state['_performance_metrics'].copy()
+            # Ensure all values are serializable
+            for key, value in safe_metrics.items():
+                if hasattr(value, '__dict__') and not isinstance(value, (list, dict, str, int, float, bool)):
+                    safe_metrics[key] = str(value)
+            state['_performance_metrics'] = safe_metrics
+        return state
         
         def __setstate__(self, state):
-            """Custom unpickling to restore object state."""
-            self.__dict__.update(state)
-            # Reinitialize any necessary components
+        """Custom unpickling to restore object state."""
+        self.__dict__.update(state)
+        # Reinitialize any necessary components
+        # Ensure performance metrics is properly initialized
+        if '_performance_metrics' not in self.__dict__:
+            self._performance_metrics = {
+                "total_requests": 0,
+                "successful_requests": 0,
+                "failed_requests": 0,
+                "average_response_time": 0.0,
+                "memory_usage": [],
+                "cpu_usage": [],
+                "timestamps": []
+            }
     
     def _initialize_default_agents(self):
         """Initialize default agent instances lazily."""
@@ -962,7 +982,9 @@ def health_check():
 
 # Apply HuggingFace Spaces GPU decorator if available
 if SPACES_AVAILABLE:
-    create_app = spaces.GPU(create_app)
+    # Only apply GPU decorator if GPU is explicitly enabled
+    if os.getenv("ENABLE_GPU", "false").lower() == "true":
+        create_app = spaces.GPU(create_app)
 
 if __name__ == "__main__":
     # Create and launch the application