"""
Slide 37: Slide 10
Section 2: LangGraph 1.0
Source: slides/section2-langgraph/section2.pptx

Сгенерировано автоматически из slide-NN.js / sectionN.pptx.
Паттерн провайдера скопирован из
bro-js/agents/teacher/assistant/src/angry_teacher/llm.py.

Запуск:
  cd langchain-evolution-deck
  cp .env.example .env   # заполни OPENAI_API_KEY
  python examples/slide-037/script.py
"""
import os
from dotenv import load_dotenv
from langchain_openai import ChatOpenAI

load_dotenv()

llm = ChatOpenAI(
    # model="openrouter/free",
    # model="qwen/qwen3.5-35b-a3b",
    model="openai/gpt-oss-20b",
    # model="nvidia/nemotron-3-nano",
    # model="qwen/qwen3.5-9b",
    base_url="https://llm.brojs.ru/v1",
    # base_url="https://api.minimax.io/v1",
    # base_url="http://0.0.0.0:8090/v1",
    # base_url="https://openrouter.ai/api/v1",
    # api_key=os.getenv("MINIMAX_API_KEY"),
    api_key=(os.getenv("OPENAI_API_KEY") or "").strip() or None,
    temperature=0.7,
    stream_usage=True,
)


# === Code from slide 37 ===
  import asyncio
  from typing_extensions import TypedDict
  from langgraph.graph import StateGraph, START, END

  class State(TypedDict):
      out: str

  def sync_node(state: State):                 # обычная функция
      return {"out": "sync-ok"}

> async def async_node(state: State):          # async тоже работает
      await asyncio.sleep(0)
>     return {"out": "async-ok"}

  g = StateGraph(State)
  g.add_node("s", sync_node)
  g.add_node("a", async_node)
  g.add_edge(START, "s")
  g.add_edge("s", "a")
  g.add_edge("a", END)
  app = g.compile()

  print(app.invoke({"out": ""}))
  print(asyncio.run(app.ainvoke({"out": ""})))

// note: snippet has 24 lines, card fits ~18