Improve image upload in debug drawer

backend/tests/test_conversation_history.py

@@ -122,6 +122,9 @@ class ConversationRecorderTest(unittest.IsolatedAsyncioTestCase):
             def add(self, value):
                 self.added.append(value)
 
+            async def flush(self):
+                return None
+
             async def get(self, _model, _session_id):
                 return conversation