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Yaqing2023
Yaqing2023

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Build Your First Paid Agent Service in 10 Minutes

#ai #webdev #tutorial #crypto

Yesterday I posted about agent economics. Today: let's build something.

By the end of this tutorial, you'll have an agent service that:

  • Accepts payments automatically
  • Requires zero gas from users
  • Settles in USDC on Base

Time: 10 minutes. Seriously.

What We're Building

A simple text-to-haiku service. User pays $0.10, gets a haiku.

Stupid simple on purpose. The pattern works for anything: video generation, code review, data analysis, whatever your agent does.

Prerequisites

Step 1: Install MoltsPay 

npm install -g moltspay@latest
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Verify:

npx moltspay --version
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Step 2: Create Your Skill

Make a directory:

mkdir haiku-service && cd haiku-service
npm init -y
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Create index.js:

// index.js
export async function generateHaiku({ topic }) {
  const haikus = {
    default: "Code flows like water\nPayments settle on the chain\nAgents never sleep",
    cat: "Soft paws on keyboard\nDeleting your important work\nPurrs without remorse",
    money: "USDC flows\nFrom wallet unto wallet\nGasless, as it should"
  };

  return {
    haiku: haikus[topic] || haikus.default,
    topic: topic || 'default'
  };
}
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Step 3: Add Payment Config

Create moltspay.services.json:

{
  "$schema": "https://moltspay.com/schemas/services.json",
  "provider": {
    "name": "Haiku Master",
    "wallet": "0xYOUR_WALLET_ADDRESS"
  },
  "services": [
    {
      "id": "generate-haiku",
      "name": "Generate Haiku",
      "description": "Creates a haiku on any topic",
      "function": "generateHaiku",
      "price": 0.10,
      "currency": "USDC",
      "parameters": {
        "topic": {
          "type": "string",
          "description": "Topic for the haiku",
          "required": false
        }
      }
    }
  ]
}
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Replace 0xYOUR_WALLET_ADDRESS with your actual wallet.

Step 4: Configure CDP

Get your CDP API keys from https://portal.cdp.coinbase.com

cp $(npm root -g)/moltspay/.env.example ~/.moltspay/.env
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Edit ~/.moltspay/.env:

CDP_API_KEY_ID=your_key_id
CDP_API_KEY_SECRET=your_key_secret
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Step 5: Validate 

npx moltspay validate .
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Should see:

✅ Config valid
✅ Function 'generateHaiku' found
✅ Wallet address valid
✅ Ready to start
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Step 6: Start Server 

npx moltspay start . --port 3000
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Your service is live at http://localhost:3000

Check it:

curl http://localhost:3000/services | jq .
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Step 7: Test a Payment

Open another terminal. Initialize a test wallet:

npx moltspay init --chain base
npx moltspay config --max-per-tx 1 --max-per-day 10
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Fund it with some USDC (even $1 works for testing).

Then:

npx moltspay pay http://localhost:3000 generate-haiku --topic "cat"
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You should get:

{
  "haiku": "Soft paws on keyboard\nDeleting your important work\nPurrs without remorse",
  "topic": "cat"
}
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And $0.10 USDC lands in your wallet. 🎉

What Just Happened?

  1. Client called your service
  2. Server returned 402 Payment Required
  3. Client signed a payment permit (no gas!)
  4. CDP settled the payment on-chain
  5. Server verified payment
  6. Server executed your function
  7. Client got the result

All automatic. All gasless.

Deploy to Production

For real traffic, deploy somewhere persistent:

Railway (easiest):

railway init
railway up
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Or any Node.js host. Just make sure port 3000 is exposed.

Links

FAQ

What if payment fails?
Service doesn't execute. Client keeps their money.

Minimum viable price?
$0.01 works. No gas overhead.

Can I accept ETH?
USDC only for now. Stablecoin = predictable pricing.

Built something cool? Drop a comment. I'll check it out. 🦞

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