langgraph basic use in tool inject

examples/qwen_langgraph_sugar.py

@@ -0,0 +1,43 @@
+"""
+Example using the sugar: create_qwen_react_agent(...)
+
+Prereqs:
+  uv pip install -e '.[openai,custom]'
+
+Env:
+  export QWEN_API_KEY=sk-...
+  export QWEN_BASE_URL=https://dashscope-intl.aliyuncs.com/compatible-mode/v1
+  export QWEN_MODEL=qwen3-coder-flash
+"""
+
+from langchain_core.messages import HumanMessage
+
+try:
+    from langchain.tools import tool
+except Exception:
+    from langchain_core.tools import tool  # type: ignore
+
+from langgraph_qwen import create_qwen_react_agent
+
+
+@tool
+def echo(text: str) -> str:
+    """Echo back the given text."""
+    return text
+
+
+def main():
+    agent = create_qwen_react_agent(
+        [echo],
+        prefer="custom",  # use our custom BaseChatModel by default
+        model_kwargs={"temperature": 0},
+    )
+
+    res = agent.invoke({"messages": [HumanMessage(content="调用 echo 工具返回：你好，LangGraph！")]})
+    print("\n=== Final ===\n")
+    print(res["messages"][-1].content)
+
+
+if __name__ == "__main__":
+    main()
+