langchain-duel

This package connects Duel Agents to LangChain.

Duel Agents routes each prompt against multiple models and bills the cheapest answer that still wins. The proxy is OpenAI wire compatible, so ChatDuel builds on langchain-openai and just points at the Duel proxy with sensible defaults.

Installation

pip install -U langchain-duel

Set your Duel API key (create one at duelagents.com/dashboard/settings):

export DUEL_API_KEY="duel_<prefix>_<secret>"

Chat models

from langchain_duel import ChatDuel

llm = ChatDuel(model="duel-auto", temperature=0)
print(llm.invoke("Explain concurrent agents in one sentence.").content)

duel-auto lets the router pick the model. You can also pass a specific model name (for example gpt-4o-mini or claude-3-5-haiku-latest) and Duel will route to that provider.

Streaming

for chunk in llm.stream("Write a haiku about routing."):
    print(chunk.content, end="", flush=True)

Configuration

License

MIT