Pip Buy

Tell Pip what you need. It asks merchants' agents for a one-time offer, checks every term in code, and you pay through PayPal. No mailing list, no subscription.

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Inspiration

Developers have pip install. I wanted pip buy.

I drink one or two cups of coffee a day and I wait for sales before I restock. To hear about a roaster's sale I have to join its mailing list or start a subscription. I want neither. I want the right coffee, at a fair price, before I run out.

What it does

You set the terms. Merchants make offers.

  • Tell Pip what you need in plain words. AI reads it and suggests products and quantity. You confirm a target price and a hard maximum.
  • Pip asks merchant agents for a one-time offer. They never see your name, email, target or maximum.
  • Code checks every term. Above your target? Wait, and request fresh offers later.
  • A merchant dashboard shows the other side: the request it received and the offer rule it controls.
  • You approve in PayPal. The merchant is paid directly. Pip reads the order back from PayPal and verifies amount, payee and capture before showing a receipt. One purchase, task closed.

How I built it

TypeScript and Express. PayPal Orders API v2 in the sandbox for order, approval, capture and read-back, with request IDs so a retry can't charge twice. The Claude API reads the request; code sets every amount, in integer cents.

Honest labels

  • Real: the PayPal sandbox payment and the Claude call.
  • Simulated: both roasters and their offers. No coffee ships and there are no real customers.
  • Not claimed: buying while you're away. That needs PayPal's saved payment methods across merchants.

Challenges

My first design held the buyer's money and paid merchants later through Payouts. That made the platform the seller, so I rebuilt it around paying the merchant directly. Payment failures were the other focus: a declined capture, a mismatched amount and a double return are all tested, and none can cause a second charge.

What I learned

Stating a need is not permission to pay. AI interprets; code enforces.

What's next

A merchant doesn't have to give everyone the same discount. It can answer one specific buying request within its own margins. Could that become a new customer-acquisition channel, with PayPal powering the payment? That's the hypothesis I want to test with real roasters.

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