@leash/buyer-kit

import { createBuyer } from '@leash/buyer-kit';
import { createKeyPairSignerFromBytes } from '@solana/kit';
import fs from 'node:fs';

const signer = await createKeyPairSignerFromBytes(
  new Uint8Array(JSON.parse(fs.readFileSync(process.env.LEASH_BUYER_SECRET_KEY!, 'utf8'))),
);

const buyer = createBuyer({
  agent: '<Core asset mint of your buyer agent>',
  rules: {
    v: '0.1',
    budget: { daily: '10', perCall: '0.01', currency: 'USDC' },
    hosts: { allow: ['api.example.com'] },
    triggers: [{ type: 'interval', seconds: 30 }],
  },
  signer, // Solana Kit TransactionPartialSigner
  networks: ['solana-devnet'], // CAIP-2 alias; mainnet works the same
  rpcUrl: 'https://api.devnet.solana.com',
  /**
   * When the seller advertises multiple `accepts[]` mints (e.g. USDC + USDG),
   * pick which one to pay with. Under the hood this becomes `preferredAsset`
   * on `createSvmBuyerFetch` — **strict**: if the seller does not offer this
   * mint, the fetch throws before settling (receipt `reason` begins with
   * `preferred_asset_unavailable`). There is no silent fallback to another
   * stablecoin.
   */
  preferredCurrency: 'USDC',
  onReceipt: async (r) => {
    await fetch(`http://localhost:8787/a/${r.agent}/receipts`, {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(r),
    });
  },
});

const { response, receipt } = await buyer.fetch('https://api.example.com/quote', {
  method: 'POST',
  body: JSON.stringify({ pair: 'SOL/USD' }),
  headers: { 'content-type': 'application/json' },
});

type ReceiptForwardConfig = {
  runnerUrl?: string;
  apiUrl?: string;
  apiKey?: string;
  fetch?: typeof globalThis.fetch;
};

type BuyerConfig = {
  agent: string;
  rules: RulesV1;
  signer: ClientSvmSigner;
  networks?: ('solana-mainnet' | 'solana-devnet' | string)[];
  rpcUrl?: string;
  /** Override or disable the default receipt fan-out. */
  receipts?: ReceiptForwardConfig;
  /**
   * Optional. The agent treasury **SPL token account** (ATA) to spend from,
   * returned by `setSpendDelegation` from `@leash/registry-utils`. Its mint
   * must match the asset the seller will demand **and** the stable you intend
   * to pay with (e.g. pass the treasury's USDG ATA when
   * `preferredCurrency: 'USDG'`). When set, every settled call signs as the
   * SPL **delegate** of this account. Recommended for production — see
   * [Fund an agent](/guides/fund-an-agent).
   */
  sourceTokenAccount?: string;
  /**
   * Preferred settlement stable: `'USDC' | 'USDT' | 'USDG'`. Resolved to a
   * mint on the first entry in `networks` and passed to the x402 client
   * selector. Omitted = default selector (first compatible `accepts[]`).
   */
  preferredCurrency?: 'USDC' | 'USDT' | 'USDG';
  /**
   * Override the default x402 facilitator URL. Defaults to
   * `devnet-facilitator.leash.market` on devnet and `facilitator.leash.market` on
   * mainnet; the env var `LEASH_FACILITATOR_URL` overrides both. Other
   * facilitators (svmacc.tech, payai.network, self-hosted) are fully supported.
   */
  facilitator?: string;
  fetch?: typeof globalThis.fetch; // injection point for tests
  /**
   * Receipt sink. Function = explicit handler. `false` = opt out of all
   * forwarding (including environment defaults). Omitted = use the
   * default fan-out resolved from `receipts` / env vars.
   */
  onReceipt?: ((r: ReceiptV1) => void | Promise<void>) | false;
};

type BuyerCallResult = {
  response: Response;
  receipt: ReceiptV1;
  /** Price the seller demanded (parsed from PAYMENT-REQUIRED on a 402). */
  quotedPrice?: ReceiptV1['price'];
  /** Reason the call did not settle (e.g. "insufficient_funds"). */
  failureReason?: string;
};