diff --git a/astrbot/core/astr_main_agent.py b/astrbot/core/astr_main_agent.py
index e168bbf400..2e7e628b19 100644
--- a/astrbot/core/astr_main_agent.py
+++ b/astrbot/core/astr_main_agent.py
@@ -1010,7 +1010,9 @@ def _append_system_reminders(
         system_content = (
             "<system_reminder>" + "\n".join(system_parts) + "</system_reminder>"
         )
-        req.extra_user_content_parts.append(TextPart(text=system_content))
+        req.extra_user_content_parts.append(
+            TextPart(text=system_content).mark_as_temp()
+        )
 
 
 async def _decorate_llm_request(
diff --git a/tests/unit/test_astr_main_agent.py b/tests/unit/test_astr_main_agent.py
index 3892a17c4b..e3e88beaba 100644
--- a/tests/unit/test_astr_main_agent.py
+++ b/tests/unit/test_astr_main_agent.py
@@ -142,8 +142,9 @@ def _setup_conversation_for_build(conv_mgr, cid: str = "conv-id") -> MagicMock:
     return conversation
 
 
-def test_append_system_reminders_includes_weekday(mock_event):
-    """Test datetime reminder includes weekday information."""
+@pytest.mark.asyncio
+async def test_append_system_reminders_includes_weekday(mock_event):
+    """Test datetime reminder includes weekday and is not persisted."""
     req = ProviderRequest(prompt="Hello")
     fixed_now = datetime.datetime(
         2026,
@@ -173,6 +174,14 @@ def now(cls, tz=None):
         "<system_reminder>Current datetime: "
         "2026-06-08 12:34 (UTC), Weekday: Monday</system_reminder>"
     ]
+    assert req.extra_user_content_parts[0]._no_save is True
+
+    message = Message.model_validate(await req.assemble_context())
+    assert isinstance(message.content, list)
+    assert message.content[1].text == req.extra_user_content_parts[0].text
+    assert dump_messages_with_checkpoints([message]) == [
+        {"role": "user", "content": [{"type": "text", "text": "Hello"}]}
+    ]
 
 
 def test_local_mode_prompt_uses_windows_powershell_51():