Shopping cart

The Aurex cart lives entirely in the browser via zustand+persist (key: aurex-cart-v1). No account, no login, no server cookie — refresh the page or reopen the browser, the cart is still there. Two pricing rules apply automatically at the cart layer: - **Stack-tier discount** — when 3+ unique non-accessory peptide vials are present, every line drops to its pricing.stackFloor. Surfaces as a "Stack pricing" line in the summary plus a 1–2 vial "Add N more to unlock" nudge. - **Free shipping threshold** — subtotal of $200+ unlocks free tracked US shipping. Below the threshold, $18 flat. Both the cart page and the slide-out drawer render a progress bar. The same lib/pricing.ts and lib/shipping.ts modules drive both the cart UI and the /api/preorder server-side total — so what the customer sees in the cart is what the order record stores. Crypto checkout discounts (-8%) apply at the rail step in /checkout, not at the cart level. Stack-tier and crypto discounts compound.