feat(ecommerce): migrate Ari Shopping to Next.js 15 headless storefront v4

workloads/ecommerce/store/cart-store.ts

@@ -0,0 +1,52 @@
+"use client";
+
+import { create } from "zustand";
+import { createJSONStorage, persist } from "zustand/middleware";
+import type { Product } from "@/lib/headless/types";
+
+export interface CartItem {
+  product: Product;
+  quantity: number;
+  variantId?: string;
+}
+
+interface CartState {
+  items: CartItem[];
+  isOpen: boolean;
+  openCart: () => void;
+  closeCart: () => void;
+  addItem: (product: Product, variantId?: string) => void;
+  removeItem: (productId: string) => void;
+  updateQuantity: (productId: string, quantity: number) => void;
+  clearCart: () => void;
+}
+
+export const useCartStore = create<CartState>()(
+  persist(
+    (set) => ({
+      items: [],
+      isOpen: false,
+      openCart: () => set({ isOpen: true }),
+      closeCart: () => set({ isOpen: false }),
+      addItem: (product, variantId) => set((state) => {
+        const existing = state.items.find((item) => item.product.id === product.id && item.variantId === variantId);
+        const items = existing
+          ? state.items.map((item) => item === existing ? { ...item, quantity: item.quantity + 1 } : item)
+          : [...state.items, { product, quantity: 1, variantId }];
+        return { items, isOpen: true };
+      }),
+      removeItem: (productId) => set((state) => ({ items: state.items.filter((item) => item.product.id !== productId) })),
+      updateQuantity: (productId, quantity) => set((state) => ({
+        items: quantity <= 0
+          ? state.items.filter((item) => item.product.id !== productId)
+          : state.items.map((item) => item.product.id === productId ? { ...item, quantity } : item),
+      })),
+      clearCart: () => set({ items: [] }),
+    }),
+    {
+      name: "ari-shopping-cart-v4",
+      storage: createJSONStorage(() => localStorage),
+      partialize: (state) => ({ items: state.items }),
+    },
+  ),
+);