fix(token-usage): enable stream usage for openai-compatible models (#2217)

* fix(token-usage): enable stream usage for openai-compatible models

* fix(token-usage): narrow stream_usage default to ChatOpenAI

backend/packages/harness/deerflow/models/factory.py

@@ -30,6 +30,22 @@ def _vllm_disable_chat_template_kwargs(chat_template_kwargs: dict) -> dict:
     return disable_kwargs
 
 
+def _enable_stream_usage_by_default(model_use_path: str, model_settings_from_config: dict) -> None:
+    """Enable stream usage for OpenAI-compatible models unless explicitly configured.
+
+    LangChain only auto-enables ``stream_usage`` for OpenAI models when no custom
+    base URL or client is configured. DeerFlow frequently uses OpenAI-compatible
+    gateways, so token usage tracking would otherwise stay empty and the
+    TokenUsageMiddleware would have nothing to log.
+    """
+    if model_use_path != "langchain_openai:ChatOpenAI":
+        return
+    if "stream_usage" in model_settings_from_config:
+        return
+    if "base_url" in model_settings_from_config or "openai_api_base" in model_settings_from_config:
+        model_settings_from_config["stream_usage"] = True
+
+
 def create_chat_model(name: str | None = None, thinking_enabled: bool = False, **kwargs) -> BaseChatModel:
     """Create a chat model instance from the config.
 
@@ -97,6 +113,8 @@ def create_chat_model(name: str | None = None, thinking_enabled: bool = False, *
         kwargs.pop("reasoning_effort", None)
         model_settings_from_config.pop("reasoning_effort", None)
 
+    _enable_stream_usage_by_default(model_config.use, model_settings_from_config)
+
     # For Codex Responses API models: map thinking mode to reasoning_effort
     from deerflow.models.openai_codex_provider import CodexChatModel
 

backend/tests/test_model_factory.py

@@ -597,6 +597,99 @@ def test_openai_compatible_provider_passes_base_url(monkeypatch):
     assert captured.get("api_key") == "test-key"
     assert captured.get("temperature") == 1.0
     assert captured.get("max_tokens") == 4096
+    assert captured.get("stream_usage") is True
+
+
+def test_openai_compatible_provider_respects_explicit_stream_usage(monkeypatch):
+    """Explicit stream_usage should not be overwritten by the factory default."""
+    model = ModelConfig(
+        name="minimax-m2.5",
+        display_name="MiniMax M2.5",
+        description=None,
+        use="langchain_openai:ChatOpenAI",
+        model="MiniMax-M2.5",
+        base_url="https://api.minimax.io/v1",
+        api_key="test-key",
+        stream_usage=False,
+        supports_vision=True,
+        supports_thinking=False,
+    )
+    cfg = _make_app_config([model])
+    _patch_factory(monkeypatch, cfg)
+
+    captured: dict = {}
+
+    class CapturingModel(FakeChatModel):
+        def __init__(self, **kwargs):
+            captured.update(kwargs)
+            BaseChatModel.__init__(self, **kwargs)
+
+    monkeypatch.setattr(factory_module, "resolve_class", lambda path, base: CapturingModel)
+
+    factory_module.create_chat_model(name="minimax-m2.5")
+
+    assert captured.get("stream_usage") is False
+
+
+def test_openai_compatible_provider_enables_stream_usage_for_openai_api_base(monkeypatch):
+    """openai_api_base should trigger stream_usage default for ChatOpenAI."""
+    model = ModelConfig(
+        name="openai-compatible",
+        display_name="OpenAI-Compatible",
+        description=None,
+        use="langchain_openai:ChatOpenAI",
+        model="example-model",
+        openai_api_base="https://example.com/v1",
+        api_key="test-key",
+        supports_vision=False,
+        supports_thinking=False,
+    )
+    cfg = _make_app_config([model])
+    _patch_factory(monkeypatch, cfg)
+
+    captured: dict = {}
+
+    class CapturingModel(FakeChatModel):
+        def __init__(self, **kwargs):
+            captured.update(kwargs)
+            BaseChatModel.__init__(self, **kwargs)
+
+    monkeypatch.setattr(factory_module, "resolve_class", lambda path, base: CapturingModel)
+
+    factory_module.create_chat_model(name="openai-compatible")
+
+    assert captured.get("openai_api_base") == "https://example.com/v1"
+    assert captured.get("stream_usage") is True
+
+
+def test_non_openai_provider_does_not_receive_stream_usage_default(monkeypatch):
+    """Non-OpenAI providers with base_url should not receive stream_usage by default."""
+    model = ModelConfig(
+        name="ollama-local",
+        display_name="Ollama Local",
+        description=None,
+        use="langchain_ollama:ChatOllama",
+        model="qwen2.5",
+        base_url="http://127.0.0.1:11434",
+        supports_vision=False,
+        supports_thinking=False,
+    )
+    cfg = _make_app_config([model])
+    _patch_factory(monkeypatch, cfg)
+
+    captured: dict = {}
+
+    class CapturingModel(FakeChatModel):
+        def __init__(self, **kwargs):
+            captured.update(kwargs)
+            BaseChatModel.__init__(self, **kwargs)
+
+    monkeypatch.setattr(factory_module, "resolve_class", lambda path, base: CapturingModel)
+
+    factory_module.create_chat_model(name="ollama-local")
+
+    assert captured.get("base_url") == "http://127.0.0.1:11434"
+    assert "stream_usage" not in captured
 
 
 def test_openai_compatible_provider_multiple_models(monkeypatch):