add langgraph use

examples/stream_modes/debug_demo.py

@@ -0,0 +1,53 @@
+from typing import TypedDict, Annotated
+import operator
+import time
+
+from langgraph.graph import StateGraph, END
+
+
+class GraphState(TypedDict):
+    messages: Annotated[list, operator.add]
+    step_count: int
+    result: str
+
+
+def step_1(state: GraphState) -> GraphState:
+    time.sleep(0.2)
+    return {"messages": ["S1"], "step_count": state.get("step_count", 0) + 1, "result": "r1"}
+
+
+def step_2(state: GraphState) -> GraphState:
+    time.sleep(0.2)
+    return {"messages": ["S2"], "step_count": state.get("step_count", 0) + 1, "result": "r2"}
+
+
+def step_3(state: GraphState) -> GraphState:
+    time.sleep(0.2)
+    return {"messages": ["S3"], "step_count": state.get("step_count", 0) + 1, "result": "done"}
+
+
+def create_workflow():
+    wf = StateGraph(GraphState)
+    wf.add_node("step_1", step_1)
+    wf.add_node("step_2", step_2)
+    wf.add_node("step_3", step_3)
+    wf.set_entry_point("step_1")
+    wf.add_edge("step_1", "step_2")
+    wf.add_edge("step_2", "step_3")
+    wf.add_edge("step_3", END)
+    return wf.compile()
+
+
+def main():
+    print("=" * 60)
+    print("🛠️  LangGraph stream_mode='debug' 示例（开发定位用）")
+    print("=" * 60)
+    app = create_workflow()
+    initial = {"messages": [], "step_count": 0, "result": ""}
+    for info in app.stream(initial, stream_mode="debug"):
+        print(info)
+
+
+if __name__ == "__main__":
+    main()
+