@barzkit/langchain

BarzKit tools for LangChain — give AI agents self-custody wallets with send, swap, lend, freeze, and x402 payments.

Installation

npm install @barzkit/langchain @barzkit/sdk @langchain/core zod

Quick Start

import { createBarzTools } from '@barzkit/langchain'
import { ChatAnthropic } from '@langchain/anthropic'
import { AgentExecutor, createToolCallingAgent } from 'langchain/agents'
import { ChatPromptTemplate } from '@langchain/core/prompts'

// 1. Create all BarzKit tools
const tools = await createBarzTools({
  chain: 'sepolia',
  owner: process.env.BARZ_OWNER_KEY as `0x${string}`,
  pimlico: { apiKey: process.env.PIMLICO_API_KEY! },
})

// 2. Create LangChain agent
const llm = new ChatAnthropic({ model: 'claude-sonnet-4-5-20250514' })
const prompt = ChatPromptTemplate.fromMessages([
  ['system', 'You are a DeFi agent with a self-custody wallet.'],
  ['human', '{input}'],
  ['placeholder', '{agent_scratchpad}'],
])
const agent = createToolCallingAgent({ llm, tools, prompt })
const executor = new AgentExecutor({ agent, tools })

// 3. Use natural language
await executor.invoke({ input: 'Send 0.01 ETH to 0x742d...' })
await executor.invoke({ input: 'Swap 100 USDC for WETH' })
await executor.invoke({ input: 'What is my wallet balance?' })

Tools

| Tool | Parameters | Description | |------|-----------|-------------| | barz_send_transaction | to, amount, token? | Send ETH or tokens | | barz_check_balance | token? | Check wallet balance | | barz_swap | from, to, amount, slippage? | Swap on Uniswap V3 | | barz_lend | token, amount, protocol? | Supply to Aave V3 | | barz_batch_transactions | transactions[] | Atomic multi-call | | barz_freeze_wallet | (none) | Emergency freeze | | barz_unfreeze_wallet | (none) | Unfreeze wallet | | barz_fetch_with_payment | url, method?, headers? | x402 auto-payment fetch |

Usage Patterns

From config (recommended)

import { createBarzTools } from '@barzkit/langchain'

const tools = await createBarzTools({
  chain: 'sepolia',
  owner: '0x...',
  pimlico: { apiKey: 'pim_...' },
})

From existing agent

import { createBarzAgent } from '@barzkit/sdk'
import { createBarzToolkit } from '@barzkit/langchain'

const agent = await createBarzAgent({ ... })
const tools = createBarzToolkit(agent)

Individual tools

import { BarzSwap, BarzCheckBalance } from '@barzkit/langchain'
import { createBarzAgent } from '@barzkit/sdk'

const agent = await createBarzAgent({ ... })
const tools = [new BarzSwap(agent), new BarzCheckBalance(agent)]

Development

npm run build    # tsup build (ESM + DTS)
npm test         # vitest unit tests
npm run lint     # tsc --noEmit type check

License

MIT