Completes the frontend half of the Payload backend's variant/inventory/
tracking work (see that repo's own commit):
- **Cart**: CartItem gained an optional `variant?: string` field — every
function that used to match a line by `id` alone (addToCart/
removeFromCart/setQuantity) now matches by `(id, variant)` together via
a shared sameLine() helper, so two lines for the same product with
different variants stay separate entries. `variant` undefined on both
sides (the no-variants case) still matches by simple equality, so every
pre-existing call site keeps working unchanged.
- **Selection UI**: AddToCartInlineButton renders a <select> above the
button when given a non-empty `variants` prop (ProductGrid/
RelatedProducts pass product.variants straight through); defaults to
the first variant.
- **Pricing**: cartTotals.ts's new effectivePrice(entry, product) — a
variant's priceOverride wins over the base product price. Every cart/
checkout/order-confirmation total and per-line price display now goes
through this instead of reading product.price directly (fixes both a
wrong-price bug and a duplicate-React-key bug the old `key={product.id}`
pattern would have had the moment two variants of one product were both
in the cart).
- **Checkout**: re-validates the requested variant server-side (same
"never trust the client" reasoning as price re-derivation) — a variant
name that doesn't exist on that product fails the whole checkout.
variantName snapshots onto orders.items, shown as a parenthetical next
to the product name on the confirmation email, both invoice PDF types,
and the order-detail page.
- **Cross-device cart**: Customers.cart[].variantName (synced via
/api/account/cart) carries the selection through a login/logout cycle,
not just the current session.
Also adds tracking-number display: /konto/bestellungen/[orderNumber]
shows a clickable link when orders.trackingNumber is set, built by a new
app/lib/tracking.ts that mirrors the Payload backend's own copy
byte-for-byte close (same carrier set/URL patterns) so what a customer
sees here matches exactly what the order-shipped email already links to.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Discount codes:
- New shared lib/cartTotals.ts (computeSubtotal/computeCartTotals) factored
out of the previously-triplicated subtotal/totalSavings/total math in
CartContent/CheckoutContent/BestellbestaetigungContent, extended to also
fold in a discount amount (percent or fixed, clamped so total can't go
negative).
- lib/discount.ts mirrors lib/cart.ts's exact localStorage pattern so an
applied code survives the /cart -> /checkout transition without a second
input field — Checkout only displays it.
- New /api/discount/validate (read-only check) and /api/discount/redeem
(re-validates + increments the redemption counter, called once from
checkout's handlePurchase right before the OrderSnapshot is written).
Both talk to Payload's new discount-codes collection through
lib/discountServer.ts, a server-only module kept separate from
lib/payload.ts on purpose (that file is also imported by "use client"
components; the RSC-boundary break hit earlier this session was exactly
this mistake with next/headers).
- OrderSnapshot gains discountCode/discountAmount so /bestellbestaetigung
displays what was actually applied instead of losing it on recompute.
RelatedProducts: no longer falls back to re-suggesting a product already
in the cart just to pad the grid out to 3 cards — shows only the
genuinely available remainder (down to 1 card), centered in the 12-column
grid instead of left-aligned.
Marco