@bursar/langchain

Spend from a Bursar mandate inside LangChain.js. Four tools: inspect, quote, pay and settlements. The mandate's limits are enforced by a contract on Robinhood Chain, so the agent cannot be talked past them.

Install

npm install @bursar/langchain @langchain/core

Node 22 or newer. ESM only. Tested against @langchain/core 1.2.17.

Use

import { bursarTools, createToolset, usdg } from '@bursar/langchain';
import { createAgent } from 'langchain';

const toolset = createToolset({ mandate: MANDATE, account: process.env.BURSAR_AGENT_KEY, spendCap: { total: usdg('5') } });
const agent = createAgent({ model: 'openai:gpt-5', tools: bursarTools(toolset) });

const result = await agent.invoke({
  messages: [{ role: 'user', content: 'Check what I can spend, then pay 0.25 USDG to 0x5210…fca374 for gpu.render:1.' }],
});

Each tool answers with a sentence the model can act on: what is allowed, what was paid and its settlement id, or which limit refused and when it resets. Amounts are USDG in six-decimal units, "250000" for 0.25 USDG.

Example

examples/pay.ts pays 0.25 USDG to the demo provider from the example mandate on mainnet, with no model in the loop: each tool is invoked the way an agent invokes it.

BURSAR_AGENT_KEY=0x… npx tsx examples/pay.ts            # inspect, quote, pay, settlements
BURSAR_AGENT_KEY=0x… npx tsx examples/pay.ts --quote    # inspect and quote only

The toolset, its options and the environment variables are documented in @bursar/toolset.