fix: preserve response-mode session scoping without Langfuse

camel/utils/langfuse.py

@@ -141,9 +141,7 @@ def get_current_agent_session_id() -> Optional[str]:
     Returns:
         Optional[str]: The session ID for the current agent.
     """
-    if is_langfuse_available():
-        return _agent_session_id_var.get()
-    return None
+    return _agent_session_id_var.get()
 
 
 def update_langfuse_trace(

test/models/test_openai_compatible_model.py

@@ -11,6 +11,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 # ========= Copyright 2023-2026 @ CAMEL-AI.org. All Rights Reserved. =========
+from unittest.mock import MagicMock
+
 import pytest
 from httpx import URL
 from pytest import MonkeyPatch
@@ -61,3 +63,38 @@ def test_openai_compatible_model_apikey_from_env(monkeypatch: MonkeyPatch):
     assert model._client.base_url == URL(url)
     assert model._async_client.api_key == api_key
     assert model._async_client.base_url == URL(url)
+
+
+def test_openai_compatible_responses_uses_agent_session_scope_when_langfuse_is_disabled(
+    monkeypatch,
+):
+    monkeypatch.setattr("camel.utils.langfuse._langfuse_configured", False)
+
+    model = OpenAICompatibleModel(
+        model_type="dummy-model",
+        api_key="dummy",
+        url="https://example.invalid",
+        api_mode="responses",
+        client=MagicMock(),
+        async_client=MagicMock(),
+    )
+
+    from camel.utils.langfuse import set_current_agent_session_id
+
+    set_current_agent_session_id("agent-a")
+    model._save_response_chain_state(
+        model._get_response_chain_session_key(), "resp_a", 2
+    )
+
+    set_current_agent_session_id("agent-b")
+    chain_state = model._prepare_responses_input_and_chain(
+        [
+            {"role": "system", "content": "system-b"},
+            {"role": "user", "content": "hello-b"},
+            {"role": "assistant", "content": "reply-b"},
+        ],
+        chain_enabled=True,
+    )
+
+    assert chain_state["session_key"] == "agent-b"
+    assert chain_state["previous_response_id"] is None

test/models/test_openai_model.py

@@ -372,6 +372,59 @@ def test_responses_mode_uses_previous_response_id_and_delta_input():
         assert second_call_kwargs["input"][-1]["content"] == "Continue"
 
 
+def test_responses_mode_uses_agent_session_scope_when_langfuse_is_disabled(
+    monkeypatch,
+):
+    monkeypatch.setattr("camel.utils.langfuse._langfuse_configured", False)
+
+    with patch("camel.models.openai_model.OpenAI") as mock_openai:
+        mock_client = MagicMock()
+        mock_openai.return_value = mock_client
+
+        mock_client.responses.create.return_value = {
+            "id": "resp_any",
+            "created_at": 1741294021,
+            "usage": {
+                "input_tokens": 1,
+                "output_tokens": 1,
+                "total_tokens": 2,
+            },
+            "output": [
+                {
+                    "type": "message",
+                    "role": "assistant",
+                    "content": [{"type": "output_text", "text": "ok"}],
+                }
+            ],
+        }
+
+        model = OpenAIModel(
+            model_type=ModelType.GPT_4O_MINI,
+            api_mode="responses",
+            api_key="dummy",
+        )
+
+        from camel.utils.langfuse import set_current_agent_session_id
+
+        set_current_agent_session_id("agent-a")
+        model._save_response_chain_state(
+            model._get_response_chain_session_key(), "resp_a", 2
+        )
+
+        set_current_agent_session_id("agent-b")
+        chain_state = model._prepare_responses_input_and_chain(
+            [
+                {"role": "system", "content": "system-b"},
+                {"role": "user", "content": "hello-b"},
+                {"role": "assistant", "content": "reply-b"},
+            ],
+            chain_enabled=True,
+        )
+
+        assert chain_state["session_key"] == "agent-b"
+        assert chain_state["previous_response_id"] is None
+
+
 def test_responses_mode_normalizes_function_tools_schema():
     with patch("camel.models.openai_model.OpenAI") as mock_openai:
         mock_client = MagicMock()