Leash
Give your agent a budget, not your card.
- Type
- AI agent + payments
- Year
- 2026
- Role
- Product idea, agent design, full-stack, visual design, demo video
- Stack
- Next.js 16, React 19, TypeScript, Vercel AI SDK, PayPal APIs, Neon Postgres
An AI agent that shops for you inside rules you sign, pays through PayPal, and asks before anything big. Built for the PayPal AI Hackathon.
AI agents can now find a product, compare it and pay for it. But would you hand one your card? Most people would not, and approving every single step defeats the point of having an agent.
Leash is the middle ground people already use with each other: an allowance with rules. You write them in plain English, the AI drafts them as a mandate, you check every number and sign. The agent then shops inside that mandate and pays through your PayPal wallet.
The limits live in the app's code, not in the AI's instructions, so the agent can only propose. The whole interface is built around financial paper: cheque stock for the rules, receipt tape for the ledger, rubber stamps for decisions and a parcel tag for each purchase.
Details worth a look
- Connect PayPal once with the Vault API, so no card numbers ever touch the app
- Rules written in plain English become a structured mandate you sign
- The agent's reasoning shown as a contact sheet: the pick circled, runner-ups struck through
- Out-of-scope requests are refused before any search, anything above your ask-first line is held for approval
- Even "I pre-approve everything" gets held, because the purchase tool only accepts items the mandate check cleared
- Every move prints on a ledger tape with the real PayPal order, capture and payout IDs, and one click refunds it
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