@prefactor/langchain

Prefactor TypeScript SDK

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Prefactor TypeScript SDK / @prefactor/langchain

@prefactor/langchain

LangChain adapter package exposing Prefactor initialization helpers and middleware.

@prefactor/langchain overview

@prefactor/langchain adds Prefactor tracing to LangChain middleware so agent, model, chain, and tool activity is captured automatically.

Use this package as a provider for the core init function.

Quick start

import { init } from '@prefactor/core';
import { PrefactorLangChain } from '@prefactor/langchain';
import { createAgent } from 'langchain';

const prefactor = init({
  provider: new PrefactorLangChain(),
  httpConfig: {
    apiUrl: 'https://api.prefactor.ai',
    apiToken: process.env.PREFACTOR_API_TOKEN!,
    agentIdentifier: 'support-bot-v1',
  },
});

const agent = createAgent({
  model: 'claude-sonnet-4-5-20250929',
  tools: [],
  middleware: [prefactor.getMiddleware()],
});

Classes

• PrefactorLangChain

Interfaces

• PrefactorLangChainOptions

Variables

• DEFAULT_LANGCHAIN_AGENT_SCHEMA