MPP Payment Proxy

Before writing code

Fetch live docs:

1. Fetch https://www.npmjs.com/package/mppx for the proxy handler API and configuration
2. Web-search mppx proxy payment 402 existing API monetize for proxy implementation patterns
3. Web-search site:github.com stripe-samples machine-payments proxy for official proxy sample code
4. Fetch https://developers.cloudflare.com/agents/agentic-payments/mpp/ for Cloudflare Workers proxy patterns

Conceptual Architecture

What the Proxy Does

The MPP proxy wraps an existing upstream API with a payment gate, requiring clients to pay before their requests are forwarded. The upstream API is unmodified — it never sees the payment flow.