// crubal.com/commerce: the machinery of selling. It attaches to items and services; it is never part of
// the core (chapter 1, "the engine is universal at the kind level").
package: commerce /2026-10-14
  owner: crubal.com
  label: Commerce
  crubal: 2
  licence: CC-BY-4.0
  extends: crubal.com/product /2026-10-14, crubal.com/service /2026-10-14
  prefixes:
    schema: https://schema.org/
    product: crubal.com/product
    service: crubal.com/service

price#currency =schema:price
compareAt#currency
cost#currency
sku$80 unique =schema:sku
stock#
offerStatus{draft|listed|reserved|sold|withdrawn}
shippingWeight#kg accepts: g, lb, oz
shipsFrom$
taxCode$

rule: listedNeedsPrice
  when: offerStatus is listed
  then: price has
  strength: must
  because: a listed offer needs a price

rule: costIsStaff
  then: cost shown to staff
  strength: must

rule: soldHasNoStock
  when: offerStatus is sold
  then: stock in 0..0
  strength: should
  because: a sold one-off has none left

class: Offer
  label: Offer
  for: item, service
  facets:
    unit::price
    unit::compareAt
    unit::cost
    unit::sku
    unit::stock
    !unit::offerStatus
    section: Shipping
    shippingWeight
    shipsFrom
    taxCode