💧 Give Your LangChain Agent a Smart Wallet on Base

#langchain #web3 #ai #blockchain

Your AI agent can write emails, search the web, and query databases. But can it deploy a smart wallet?

Now it can.

I just published @spraay/langchain-agent-wallet — 5 LangChain StructuredTool classes that let your agent provision smart wallets, manage session keys, and predict wallet addresses on Base. Every call is paid with USDC micropayments via the x402 protocol. No API keys. No subscriptions. Just pay-per-call.

The Problem

AI agents are getting good at planning and reasoning. But when it comes to actually holding money and executing transactions, most frameworks punt. You end up with the agent's private key embedded in code, full access to everything, zero permission scoping.

That's not how you'd let a human employee operate. Why let your agent?

The Solution: Agent Wallets with Session Keys

Spraay's Agent Wallet infrastructure deploys a smart contract wallet for each agent on Base. The wallet is owned by you, but the agent gets a session key — a scoped, time-limited permission to act on behalf of the wallet.

Think of it like giving an employee a corporate card with a spending limit instead of handing them the company bank login.

The 5 Tools

npm install @spraay/langchain-agent-wallet @langchain/core

Tool	What it does	Cost
`spraay_provision_wallet`	Deploy a new smart wallet on Base	$0.05
`spraay_add_session_key`	Grant scoped permissions to an address	$0.02
`spraay_get_wallet_info`	Query wallet details and balance	$0.005
`spraay_revoke_session_key`	Remove a session key	$0.02
`spraay_predict_address`	Pre-compute CREATE2 wallet address	$0.001

Quick Start

import { ChatOpenAI } from "@langchain/openai";
import { createToolCallingAgent, AgentExecutor } from "langchain/agents";
import { ChatPromptTemplate } from "@langchain/core/prompts";
import { createSpraayWalletTools } from "@spraay/langchain-agent-wallet";

// Create all 5 tools with one function
const tools = createSpraayWalletTools({
  privateKey: process.env.EVM_PRIVATE_KEY!,
});

const llm = new ChatOpenAI({ model: "gpt-4o" });

const prompt = ChatPromptTemplate.fromMessages([
  ["system", "You are a Web3 agent that manages smart wallets on Base."],
  ["human", "{input}"],
  ["placeholder", "{agent_scratchpad}"],
]);

const agent = createToolCallingAgent({ llm, tools, prompt });
const executor = new AgentExecutor({ agent, tools });

// The agent decides which tool to call based on natural language
const result = await executor.invoke({
  input: "Deploy a new wallet for 0x1234...abcd labeled 'treasury'",
});

The LLM reads the tool descriptions and zod schemas to figure out which tool to call and what parameters to pass. You don't write any routing logic.

How x402 Payments Work

Every tool call hits the Spraay gateway at gateway.spraay.app. Instead of an API key, the request includes a signed payment header — your agent's private key authorizes a USDC micropayment on Base.

The gateway verifies the signature, settles the payment, and executes the operation. It's like HTTP 402 (Payment Required) actually working the way it was supposed to.

This means: