fix(tests): update two more append_message.call_args assertions to append_messages_batch

CI-caught: test_verification_stop_caching and test_tui_gateway_server::test_native_vision_turn_persists_a_renderable_image_ref both assert on append_message.call_args, but the flush loop now calls append_messages_batch. Same class of test-fake fallout fixed in 5 other files — these two were missed.

tests/agent/test_verification_stop_caching.py

@@ -84,8 +84,9 @@ def test_db_flush_drops_only_nudge_keeps_candidate(tmp_path, monkeypatch):
     agent._flush_messages_to_session_db(messages, conversation_history=[])
 
     persisted = [
-        kwargs.get("content")
-        for _args, kwargs in agent._session_db.append_message.call_args_list
+        msg.get("content")
+        for _args, kwargs in agent._session_db.append_messages_batch.call_args_list
+        for msg in kwargs["messages"]
     ]
     assert "hi" in persisted
     assert "verified and clean" in persisted

tests/test_tui_gateway_server.py

@@ -16063,7 +16063,7 @@ def test_native_vision_turn_persists_a_renderable_image_ref(tmp_path):
 
     agent._flush_messages_to_session_db([{"role": "user", "content": native_parts}], [])
 
-    written = agent._session_db.append_message.call_args.kwargs["content"]
+    written = agent._session_db.append_messages_batch.call_args.kwargs["messages"][0]["content"]
     assert f"@image:`{img}`" in written
     assert "what is in this photo?" in written
     # The model keeps the pixels for the rest of the session.