langchain-doubleword

A LangChain integration package for Doubleword.

This package wires Doubleword's OpenAI-compatible inference API (https://api.doubleword.ai/v1) into LangChain and LangGraph as both real-time chat / embedding models and transparently-batched variants powered by autobatcher.

The batched variants are required to access models that Doubleword exposes only via the batch API, and they cut cost on workloads that fan out many concurrent calls — typically the case in LangGraph agents.

Installation

pip install langchain-doubleword

Authentication

Three resolution paths, in precedence order:

1. Explicit constructor argument:

   ChatDoubleword(model="...", api_key="sk-...")

2. Environment variable:

   export DOUBLEWORD_API_KEY=sk-...

3. ~/.dw/credentials.toml — the same file written by Doubleword's CLI tooling. The active account is selected by ~/.dw/config.toml's active_account field, and inference_key from that account is used.

   # ~/.dw/config.toml
   active_account = "work"

   # ~/.dw/credentials.toml
   [accounts.work]
   inference_key = "sk-..."

   To use a non-active account from your credentials file, set DOUBLEWORD_API_KEY directly to that account's inference_key — there is no account= selector on the model itself.

Chat models

ChatDoubleword (real-time)

Drop-in chat model. Use this in any LangChain or LangGraph workflow that expects a BaseChatModel.

from langchain_doubleword import ChatDoubleword

llm = ChatDoubleword(model="your-model-name")

response = llm.invoke("Explain bismuth in three sentences.")
print(response.content)

ChatDoublewordBatch (transparently batched)

Same interface, but every concurrent .ainvoke() call is collected by autobatcher and submitted via Doubleword's batch endpoint. Async-only — sync .invoke() raises.

Use this when:

• The model you want is batch-only (some Doubleword-hosted models do not expose a real-time chat endpoint).
• You're running a LangGraph workflow with parallel branches and want ~50% cost savings via batch pricing.

import asyncio
from langchain_doubleword import ChatDoublewordBatch

llm = ChatDoublewordBatch(model="batch-only-model")

async def main():
    # Concurrent calls collected into a single batch under the hood.
    results = await asyncio.gather(*[
        llm.ainvoke(f"Summarize chapter {i}") for i in range(50)
    ])
    for r in results:
        print(r.content)

asyncio.run(main())

Tuning autobatcher

Four autobatcher.BatchOpenAI knobs are exposed as constructor arguments:

Argument	Default	Purpose
batch_size	1000	Submit a batch when this many requests are queued.
batch_window_seconds	10.0	Submit a batch after this many seconds even if the size cap is not reached.
poll_interval_seconds	5.0	How often autobatcher polls for batch completion.
completion_window	"24h"	Doubleword batch completion window. "1h" is more expensive but faster.

llm = ChatDoublewordBatch(
    model="your-model",
    batch_size=250,           # smaller batches for fast-turnaround LangGraph nodes
    batch_window_seconds=2.5, # don't make latency-sensitive calls wait 10s
    completion_window="1h",   # pay more, finish quicker
)

The same arguments are available on DoublewordEmbeddingsBatch.

Embeddings

from langchain_doubleword import DoublewordEmbeddings, DoublewordEmbeddingsBatch

embed = DoublewordEmbeddings(model="your-embedding-model")
vec = embed.embed_query("hello world")

# Or, transparently batched:
batch_embed = DoublewordEmbeddingsBatch(model="your-embedding-model")
# vecs = await batch_embed.aembed_documents([...])

Use with LangGraph

ChatDoubleword and ChatDoublewordBatch are standard BaseChatModel implementations, so they slot into any LangGraph node:

from langgraph.graph import StateGraph, END
from langchain_doubleword import ChatDoublewordBatch

llm = ChatDoublewordBatch(model="your-model")

async def call_model(state):
    response = await llm.ainvoke(state["messages"])
    return {"messages": [response]}

graph = StateGraph(dict)
graph.add_node("model", call_model)
graph.set_entry_point("model")
graph.add_edge("model", END)
app = graph.compile()

When several model nodes execute in parallel (e.g. via Send or fan-out edges), autobatcher collects their requests into a single batch.

Configuration

Argument	Env var	Default
api_key	DOUBLEWORD_API_KEY	required
base_url	DOUBLEWORD_API_BASE	https://api.doubleword.ai/v1
model	—	required

All other arguments accepted by langchain_openai.ChatOpenAI are forwarded unchanged (temperature, max_tokens, model_kwargs, timeout, etc.).

License

MIT