Create app.py

app.py

@@ -0,0 +1,77 @@
+from fastapi import FastAPI
+from langgraph.graph import StateGraph
+from typing import TypedDict, Annotated, List
+from langgraph.graph.message import add_messages
+from pydantic import BaseModel
+
+# Initialize FastAPI app
+app = FastAPI(title="LangGraph Agent API")
+
+class State(TypedDict):
+    messages: Annotated[list[str], add_messages]
+    current_step: str
+
+class AgentInput(BaseModel):
+    messages: List[str]
+
+def collect_info(state: State) -> dict:
+    print("\n--> In collect_info")
+    print(f"Messages before: {state['messages']}")
+    
+    messages = state["messages"] + ["Information collected"]
+    print(f"Messages after: {messages}")
+    
+    return {
+        "messages": messages,
+        "current_step": "process"
+    }
+
+def process_info(state: State) -> dict:
+    print("\n--> In process_info")
+    print(f"Messages before: {state['messages']}")
+    
+    messages = state["messages"] + ["Information processed"]
+    print(f"Messages after: {messages}")
+    
+    return {
+        "messages": messages,
+        "current_step": "end"
+    }
+
+# Create and setup graph
+workflow = StateGraph(State)
+
+# Add nodes
+workflow.add_node("collect", collect_info)
+workflow.add_node("process", process_info)
+
+# Add edges
+workflow.add_edge("collect", "process")
+
+# Set entry and finish points
+workflow.set_entry_point("collect")
+workflow.set_finish_point("process")
+
+# Compile the workflow
+agent = workflow.compile()
+
+
+@app.post("/run-agent")
+async def run_agent(input_data: AgentInput):
+    """
+    Run the agent with the provided input messages.
+    """
+    initial_state = State(messages=input_data.messages, current_step="collect")
+    final_state = agent.invoke(initial_state)
+    return {"messages": final_state["messages"]}
+
+@app.get("/")
+async def root():
+    """
+    Root endpoint that returns basic API information.
+    """
+    return {"message": "LangGraph Agent API is running", "endpoints": ["/run-agent"]}
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run(app, host="0.0.0.0", port=7860)