# Proxy Checkout developer documentation

Proxy adds a shareable payer handoff to an existing Stripe or Shopify checkout.
The merchant keeps payment, cart, fulfillment, and entitlement ownership.

## Start here
- Provider-first start: /guides/quickstart/
- Stripe decision guide: /guides/stripe-integration-paths/
- Shopify fit, current availability, and setup: /guides/shopify/
- Coding-agent handoff: /guides/agent-integration/

## Machine-readable routing and canonical facts
- Integration routing index: /integration-paths.json
- Canonical Stripe capability manifest: /stripe-integration-capabilities.json
- OpenAPI: /openapi/proxy-api.json

## Agent rules
1. Identify Stripe versus Shopify from the provider that owns final checkout.
2. For Stripe, identify one-time payments, subscriptions, or both.
3. Determine whether Checkout creates the Stripe object or the application creates it directly.
4. Ask hosted, embedded, or custom presentation only for Checkout.
5. Select a human path before using its technical ID.
6. Use Node.js 22 or newer. Install the public CLI if the proxy command is unavailable:
   npm install --global @proxy-checkout/cli
7. Follow the linked terminal guide and validate Stripe facts with:
   proxy stripe doctor --path <id> --format json
8. Install stripe at the exact server_sdk version reported by stripe doctor before copying backend code.
9. For embedded or custom Checkout, install @stripe/stripe-js and @stripe/react-stripe-js at the exact browser_sdk and react_sdk versions reported by stripe doctor.
10. Do not infer Shopify availability. Read the routing index and stop for approved access when required.
11. Do not fulfill from browser navigation; use signed evidence and idempotent merchant logic.

## CLI schemas
- proxy commands schema --format json
- proxy --llms-full