LangChain

LangChain works against ai& through ChatOpenAI — point it at the ai& base URL and your existing chains, agents, and graphs work unchanged.

Setup

pip install langchain langchain-openai

from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    model="openai/gpt-oss-120b",
    base_url="https://api.aiand.com/v1",
    api_key="sk-your-api-key",
)

print(llm.invoke("Hello").content)

In a chain

from langchain_core.prompts import ChatPromptTemplate

prompt = ChatPromptTemplate.from_messages([
    ("system", "Translate the user's input to {language}."),
    ("user", "{text}"),
])

chain = prompt | llm

print(chain.invoke({"language": "Japanese", "text": "Hello, world!"}).content)

With tools

from langchain_core.tools import tool

@tool
def get_weather(city: str) -> str:
    """Get current weather for a city."""
    return f"Sunny in {city}, 22°C"

llm_with_tools = llm.bind_tools([get_weather])
response = llm_with_tools.invoke("What's the weather in Tokyo?")
print(response.tool_calls)

LangGraph

LangGraph nodes that wrap ChatOpenAI work the same way — there’s nothing ai&-specific. See LangGraph docs.