How to monetize an API endpoint with Leash seller-kit

1. Open /creator/monetize.
2. Paste your existing endpoint URL.
3. Choose GET or POST as the request type buyers should use.
4. For POST, add an expected request body JSON object such as {"prompt":"string"}.
5. Choose x402 or MPP and USDC, USDT, or USDG pricing.
6. Select the seller identity and active marketplace API key.
7. Click Create payable endpoint.
8. Optional: click Add to marketplace discovery, or paste the hosted URL into /creator/list later.
9. In /creator/list, Leash reads the payable endpoint metadata and uses the endpoint owner identity for trust checks.

Existing endpoint:
GET https://jsonplaceholder.typicode.com/posts

Creator → Monetize endpoint stores:
method: GET
metadata.upstream_url: https://jsonplaceholder.typicode.com/posts
price: 0.001 USDC
rail: x402

Hosted payable endpoint:
GET https://api.leash.market/x/jsonplaceholder-posts?network=solana-devnet

What happens at runtime:
1. A buyer calls the hosted Leash URL.
2. The unpaid request receives HTTP 402 payment instructions.
3. The buyer-kit paid retry settles the payment.
4. After settlement, Leash forwards the request to metadata.upstream_url.
5. The buyer receives the live upstream JSON response, not a template body.

Existing endpoint:
POST https://api.example.com/design

Creator → Monetize endpoint stores:
method: POST
metadata.upstream_url: https://api.example.com/design
metadata.expected_request_body: {"prompt":"string","style":"string","format":"string"}

Buyer runtime request:
POST https://api.leash.market/x/design-agent?network=solana-devnet
{"prompt":"Design a hero section","style":"premium dark mode","format":"html"}

After settlement, Leash forwards that buyer body to the upstream design endpoint.

import { Hono } from 'hono';
import { createUmi } from '@metaplex-foundation/umi-bundle-defaults';
import { mplCore } from '@metaplex-foundation/mpl-core';
import { mplToolbox } from '@metaplex-foundation/mpl-toolbox';
import { createSeller } from '@leashmarket/seller-kit';

const app = new Hono();
const umi = createUmi(process.env.SOLANA_RPC)
  .use(mplCore())
  .use(mplToolbox());

process.env.LEASH_API_URL = 'https://api.leash.market';
process.env.LEASH_API_KEY = '<your-leash-api-key>';

createSeller(app, {
  umi,
  sellerAgent: { asset: '<your-leash-agent-address>' },
  network: 'solana-devnet',
  facilitator: 'https://facilitator-devnet.leash.market',
  routes: {
    'GET /paid/quote': {
      description: 'Paid quote endpoint',
      price: '0.001 USDC',
      currency: 'USDC',
      acceptsCurrencies: ['USDT', 'USDG'],
    },
  },
});

app.post('/paid/quote', async (c) => {
  const { query } = await c.req.json();
  const upstream = await fetch('https://api.example-search.com/v1/search', {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify({ query, limit: 5 }),
  });
  if (!upstream.ok) return c.json({ error: 'search_failed' }, 502);
  const data = await upstream.json();
  return c.json({ ok: true, results: data.results });
});

# Starts a local seller route, confirms the unpaid 402, then pays with buyer-kit.
pnpm --filter @leashmarket/api exec tsx \
  --env-file-if-exists=.env.e2e \
  scripts/seller-kit-local-smoke.ts

createSeller(app, {
  umi,
  sellerAgent: { asset: process.env.LEASH_SELLER_AGENT! },
  network,
  routes,
  onReceipt: async (receipt) => {
    await fetch(`${process.env.LEASH_API_URL}/v1/receipts/${receipt.agent}`, {
      method: 'POST',
      headers: {
        'content-type': 'application/json',
        authorization: `Bearer ${process.env.LEASH_API_KEY}`
      },
      body: JSON.stringify(receipt),
    });
  },
});