Billing

@caisson/billing wires Stripe and Stripe Tax, with the operator as the merchant of record — Stripe Tax computes and collects tax on the sale. Stripe sits behind a BillingProvider port, so the rest of the base depends on the port, not the vendor.

The contract

Webhooks are verified against the raw request body with a timing-safe HMAC compare. A body that has been parsed and re-serialized fails verification — the signature is over the exact bytes Stripe sent, not the JSON your framework reconstructed.

import { verifyWebhook } from "@caisson/billing";

// Raw body — never the parsed JSON. HMAC compared with timingSafeEqual.
const event = verifyWebhook(rawBody, req.headers["stripe-signature"]);

Because billing rides a port, a test driver stands in for Stripe under the standards gate — suites assert on charge and webhook behavior without a network call.

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