Update main.py

Add timestamp heristics

main.py

@@ -311,7 +311,8 @@ async def save_data(
             "query": [],
             "retrieved_text": [],
             "model_type": [],
-            "reaction": []
+            "reaction": [],
+            "timestamp": []
         }
         
         # Add each item to the data dict
@@ -322,6 +323,7 @@ async def save_data(
             data["retrieved_text"].append(item.retrieved_text)
             data["model_type"].append(item.model_type)
             data["reaction"].append(item.reaction)
+            data["timestamp"].append(timestamp or datetime.now(timezone.utc).isoformat().replace('+00:00', 'Z'))
         
         try:
             # Load existing dataset and merge
@@ -334,7 +336,7 @@ async def save_data(
             # Add new data
             for key in data:
                 if key not in existing_data:
-                    existing_data[key] = ["" if key in ["username", "model_type"] else None] * len(next(iter(existing_data.values())))
+                    existing_data[key] = ["" if key in ["timestamp"] else None] * len(next(iter(existing_data.values())))
                 existing_data[key].extend(data[key])
         
         except Exception as e: