diff --git a/backend/tests/unit/core/agentscope/runtime/test_tasks.py b/backend/tests/unit/core/agentscope/runtime/test_tasks.py
index 94d30ca..36d1ac8 100644
--- a/backend/tests/unit/core/agentscope/runtime/test_tasks.py
+++ b/backend/tests/unit/core/agentscope/runtime/test_tasks.py
@@ -57,6 +57,11 @@ async def test_run_agentscope_task_calls_runtime_run(
         _fake_get_redis_client,
     )
     monkeypatch.setattr(tasks_module, "AsyncSessionLocal", lambda: _FakeSessionCtx())
+    monkeypatch.setattr(
+        tasks_module,
+        "_build_recent_context_messages",
+        lambda **_: [],
+    )
 
     result = await tasks_module.run_agentscope_task(
         {
@@ -107,6 +112,11 @@ async def test_run_agentscope_task_includes_recent_context_messages(
         _fake_get_redis_client,
     )
     monkeypatch.setattr(tasks_module, "AsyncSessionLocal", lambda: _FakeSessionCtx())
+    monkeypatch.setattr(
+        tasks_module,
+        "_build_recent_context_messages",
+        lambda **_: [],
+    )
     monkeypatch.setattr(
         tasks_module,
         "_build_recent_context_messages",