HITL Overview

"""LangGraph agent backing the In-Chat HITL (useHumanInTheLoop) demo.The `book_call` tool is defined on the frontend via `useHumanInTheLoop`,so there is no backend tool here. CopilotKitMiddleware is attached so thefrontend suggestions and the time-picker render hook are picked up."""from langchain.agents import create_agentfrom langchain_openai import ChatOpenAIfrom copilotkit import CopilotKitMiddlewaregraph = create_agent(    model=ChatOpenAI(model="gpt-4o-mini"),    tools=[],    middleware=[CopilotKitMiddleware()],    system_prompt=(        "You help users book an onboarding call with the sales team. "        "When they ask to book a call, call the frontend-provided "        "`book_call` tool with a short topic and the user's name. "        "Keep any chat reply to one short sentence."    ),)

"""LangGraph agent for the Interrupt-based Generative UI demo.Defines a backend tool `schedule_meeting(topic, attendee)` that useslanggraph's `interrupt()` primitive to pause the run and surface themeeting context to the frontend. The frontend `useInterrupt` renderershows a time picker and resolves with `{chosen_time, chosen_label}` or`{cancelled: true}`, which this tool turns into a human-readable result."""from __future__ import annotationsfrom typing import Any, Optionalfrom langchain.agents import create_agentfrom langchain_core.tools import toolfrom langchain_openai import ChatOpenAIfrom langgraph.types import interruptfrom copilotkit import CopilotKitMiddlewareSYSTEM_PROMPT = (    "You are a scheduling assistant. Whenever the user asks you to book a "    "call / schedule a meeting, you MUST call the `schedule_meeting` tool. "    "Pass a short `topic` describing the purpose and `attendee` describing "    "who the meeting is with. After the tool returns, confirm briefly "    "whether the meeting was scheduled and at what time, or that the user "    "cancelled.")@tooldef schedule_meeting(topic: str, attendee: Optional[str] = None) -> str:    """Ask the user to pick a time slot for a call, via an in-chat picker.    Args:        topic: Short human-readable description of the call's purpose.        attendee: Who the call is with (optional).    Returns:        Human-readable result string describing the chosen slot or        indicating the user cancelled.    """    # langgraph's `interrupt()` pauses execution and forwards the payload to    # the client. The frontend v2 `useInterrupt` hook renders the picker and    # calls `resolve(...)` with the user's selection, which comes back here.    response: Any = interrupt({"topic": topic, "attendee": attendee})    if isinstance(response, dict):        if response.get("cancelled"):            return f"User cancelled. Meeting NOT scheduled: {topic}"        chosen_label = response.get("chosen_label") or response.get("chosen_time")        if chosen_label:            return f"Meeting scheduled for {chosen_label}: {topic}"    return f"User did not pick a time. Meeting NOT scheduled: {topic}"model = ChatOpenAI(model="gpt-4o-mini")graph = create_agent(    model=model,    tools=[schedule_meeting],    middleware=[CopilotKitMiddleware()],    system_prompt=SYSTEM_PROMPT,)