LangGraph

This guide shows how to integrate the AgentDuet SDK with LangGraph for durable agent workflows, including checkpointed state, human-in-the-loop interrupts, and policy-gated tools.

What this integration provides

A voice agent that:

• Answers inbound calls and bridges 24 kHz PCM to Gemini Live
• Authenticates demo orders against a local mock database (no live store APIs)
• Speaks shipping status in one or two short sentences
• Allows address changes or cancellations only when fulfillment is unfulfilled

How the pieces fit

PCM stays on the AgentDuet ↔ Gemini bridge. Graph checkpoints store compact business state only (order id, auth, fulfillment), not audio.

Prerequisites

• Python 3.12+
• AgentDuet API key and connector UUID from agentduet.com
• Gemini API key for Gemini Live

Step 1: Clone the sample

git clone https://github.com/AgentDuet/agentduet-samples.git
cd agentduet-samples/integrations/langgraph/order-tracking

Layout:

order-tracking/
├── main.py              # SessionManager + Gemini Live bridge
├── graph.py             # LangGraph OrderSession + tools
├── orders.py            # Mock DB helpers
├── prompts.py           # System prompt + greeting
├── data/orders.json     # Seed orders #1001 / #1002
├── requirements.txt
└── .env.example

Step 2: Install dependencies

python3.12 -m venv .venv
source .venv/bin/activate   # Windows: .venv\Scripts\activate
pip install -r requirements.txt

The sample pins agentduet==1.0.0.

Step 3: Configure .env

cp .env.example .env

AGENTDUET_API_KEY=your-connector-api-key
AGENTDUET_CONNECTOR_UUID=your-connector-uuid
GEMINI_API_KEY=your-gemini-api-key

Step 4: Run locally

python main.py

Call your agent. It should answer and walk order status or a change/cancel.

Demo orders

Example scripts:

1. “Order 1001, zip 94107.” → short spoken status.
2. “Change my address to 88 Folsom Street, San Francisco, California, 94105.” → succeeds on #1001.
3. “Order 1002, zip 10001. Please cancel.” → status OK; cancel politely declined.

Step 5: How LangGraph and AgentDuet connect

SessionManager answers the call

From main.py:

@sm.on_incoming_call
async def on_call(noti: IncomingCallNotification) -> None:
    session = await sm.open_session(new_session_id(), noti.subscriber)
    call = await session.process_call(noti)
    await handle_call(call)

LangGraph owns tools and call state

From graph.py, each call builds an OrderSession with checkpointed OrderState (thread id = call id) and LangChain tools:

• authenticate_order: mock DB lookup by order id + zip
• check_fulfillment_status: policy gate before modifications
• change_shipping_address / cancel_order: allowed only when unfulfilled
• hang_up: end the call after the caller says goodbye

Gemini Live receives the tool declarations and dispatches through OrderSession.ainvoke_tool.

Voice prompt rules

The system prompt in prompts.py instructs the agent to:

• Greet inbound callers and collect a test order id (#1001 / #1002) plus zip
• Authenticate via the mock database tool (never invent status)
• Speak shipping status in one or two concise sentences
• Check fulfillment before modifications; decline politely when fulfilled
• Say a short goodbye and call hang_up when the caller is done
• Keep spoken replies short

Notes

• Keep call control and PCM buffering on the AgentDuet path; put order policy in LangGraph tools.
• Map graph thread ids to stable conversation keys (this sample uses call.id).
• Restarting the process reloads seed orders from data/orders.json.
• This sample uses 24 kHz audio (CallAudioConfig(sample_rate=24000)).

Related

• Gemini Live
• Google ADK
• Amazon Bedrock AgentCore
• Order tracking sample on GitHub

Next Step