# Documenter — F-020 Shipping module

## Summary
Shipping module exposes server-side shipping quotation behind `ShippingService.calculate(cartTotalCents, address)`. Selection uses country plus most specific postal code prefix and the cheapest active method wins.

## Public API notes

| Route | Access | Result |
|---|---|---|
| POST /shipping/zones | admin | Creates a zone with country and optional postal-code prefix |
| POST /shipping/methods | admin | Creates a method under a zone with optional free-shipping threshold |
| POST /shipping/calculate | public | Returns cheapest active method cost with free shipping applied when threshold met |

## Errors
- `SHIPPING_ZONE_NOT_FOUND` — HTTP 422
- `INVALID_SHIPPING_ADDRESS` — HTTP 400

## Evidence
- `work/artifacts/F-020/architect.md`
- `work/artifacts/F-020/implementer.md`
- `work/artifacts/F-020/reviewer.json`
- `work/artifacts/F-020/security.json`
- `work/artifacts/F-020/qa.json`