CONTROL MODEL
Make the purchase request a clear system object.
An agent should act on a bounded request, not a vague goal. A good request names the item, allowed alternatives, price limit, delivery need, and the person who can approve payment. This structure lets the agent work while people keep control of the important decisions.
SHOPSTACK SCOPE // Shopstack is a checkout execution layer for AI agents. It starts a checkout with a product URL and purchase constraints, runs the merchant checkout, reports canonical progress, and pauses at typed user boundaries.
Purchase request
Item, limits, delivery, and allowed changes.
Checkout process
Find, compare, prepare, and report progress.
Protected approval
Review the final payment decision in a trusted flow.
A checkout record should show what the agent did and where it needs help. It is not permission for the agent to spend money.
A protocol moves structured requests between systems. Browser execution works on a merchant site. Checkout execution tracks the work and moves the process to help or approval when needed. These roles can work together. They do not remove the protected payment boundary.
CONSENT AND PAYMENT
Keep conversation, consent, and payment apart.
The user or service defines the purchase scope before the agent starts work.
A message can explain a problem or collect missing details. It cannot approve payment.
Payment approval happens only at the dedicated trusted boundary, after the final terms are ready for review.
IMPLEMENTATION PATH
Build the control path before you add agent work.
- 01
Define the purchase scope
Give the agent a clear item request, budget limit, delivery details, and rules for substitutions.
- 02
Create a controlled checkout
Use a checkout record to hold the request, progress, and requests for help. Keep the record separate from payment approval.
- 03
Show the decision point
When the total or merchant state needs review, show a clear request for help or approval to the authorized person.
- 04
Approve at a trusted boundary
Accept payment approval only through the dedicated protected flow. Then submit the purchase and return the result.
READY TO BUILD?
Read the setup guideFURTHER READING
Use primary sources for risk and payment design.
These sources describe general risk and payment-security work. Review the rules that apply to your product, payment method, and location.
LIMITS // This guide describes general controls. Merchant flows, payment methods, and local rules can vary.
- NIST AI Risk Management Framework
Risk-management guidance for AI systems.
- PCI Data Security Standard
Security requirements for payment account data.
- W3C Payment Request API
A web standard for payment request interfaces.