0.4.3 - 2026-09-05

PR #31 plus the post-merge review in
dev_docs/pull_requests/2026/31-currency-hygiene/CLAUDE_REVIEW.md.

Added

• Carts and cart lines require a currency. Cart.changeset/2 and
  CartItem.changeset/2 validate :currency as required, and Cart,
  CartItem, Product and ShippingMethod drop their default: "USD"
  field default. get_default_currency_code/0 returns nil, not "USD",
  when Billing has no default currency configured, so an empty currency
  table produces a loud changeset error out of create_cart/1 instead of a
  cart silently denominated in dollars. (#31)
• The shop's base currency is substituted once, at creation. A new
  context-level fallback in create_product/1 and
  create_shipping_method/1 fills in the default currency for callers that
  omit it — the admin forms and the CSV/Shopify importer alike — matching
  the incoming attrs map's key style (atom vs string) first, because
  Ecto.Changeset.cast/3 raises on a mixed-key map and the callers
  disagree. A caller that passes :currency is never overridden. (#31)
• Migration chain V2: DROP DEFAULT on the four currency columns.
  Dropping the Elixir-side default: "USD" did not remove the literal —
  core's baseline declares DEFAULT 'USD' on phoenix_kit_shop_carts,
  …_cart_items, …_products and …_shipping_methods, and Ecto omits an
  unchanged field from the INSERT, so Postgres substituted it: the struct
  came back with currency: nil and the row said "USD". V2 drops those
  column defaults, so an insert that names no currency stores NULL.
  Existing rows are untouched and down/1 restores the defaults. This is
  the chain's first deliberate divergence from core's shape. (#31)

Fixed

• The cart page no longer crashes when no default currency is
  configured. create_cart/1 gained a failure mode with the new
  validate_required, but its two storefront callers still hard-matched
  {:ok, cart} — so a shop in that state answered every cart-page request,
  and every add-to-cart, with a MatchError. Both now take the same "The
  shop is currently unavailable" exit the disabled-shop gate takes. (#31)
• The shipping-method form's "USD" literals are gone, in the hidden
  input and in the text beside it; an unconfigured default currency now
  reads "No default currency configured" and submits no currency. The
  comment claiming validate_length(:currency, is: 3) would reject that is
  corrected — validate_length skips nil and the hidden input's "" is
  an Ecto empty value, so the method is simply stored without a currency.
  (#31)

Changed

• The test harness applies the module-owned migration chain on top of
  core's migrations. V1 was purely adoptive so skipping it changed nothing;
  V2 is not, and a test database that never ran it would still hand out
  "USD" behind the schemas' backs. migrations_test.exs's
  destructive-statement scan now matches DROP by the object kind that
  follows it, so DROP DEFAULT passes while every DROP that can lose data
  or structure is still refused. (#31)