feat(cart): price options and richer cart items (both additive)

- shop.cart.prices_as_options (env SHOP_CART_PRICES_AS_OPTIONS, default off):
  adding a ProductPrice of a plain (non-pool, non-booking) product stores the
  product as the line with that price_id, so cart, checkout line and invoice
  show the product and its option. Lines merge only with the same option.
- CartItemResource adds price_id, parameters (what the buyer attached, e.g. a
  brief) and purchasable.virtual (no shipping needed).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

config/shop.php

@@ -240,6 +240,10 @@ return [
 
     // Cart configuration
     'cart' => [
+        // Adding a ProductPrice of a plain product stores the product with that price as the
+        // line (name, photo, checkout, invoice show the product and option). Off by default.
+        'prices_as_options' => env('SHOP_CART_PRICES_AS_OPTIONS', false),
+
         'expire_after_days' => 30,
         'auto_cleanup' => true,
         'merge_on_login' => true,

src/Http/Resources/CartItemResource.php

@@ -33,12 +33,18 @@ class CartItemResource extends JsonResource
             'regular_price' => $this->regular_price === null ? null : (int) $this->regular_price,
             'subtotal' => $this->subtotal === null ? null : (int) $this->subtotal,
             'currency' => $this->currency,
+            // The chosen price (a product sold in several options) and what the buyer
+            // attached to this line (e.g. a brief); both null/empty when unused.
+            'price_id' => $this->price_id,
+            'parameters' => (object) ((array) ($this->parameters ?? [])),
             'purchasable' => $purchasable ? [
                 'id' => $purchasable->getKey(),
                 'name' => $purchasable->name ?? null,
                 'slug' => $purchasable->slug ?? null,
                 'type' => $this->purchasableType($purchasable),
                 'image' => $this->resolveImage($purchasable),
+                // Virtual products (services, downloads) need no shipping.
+                'virtual' => (bool) ($purchasable->virtual ?? false),
             ] : null,
         ];
     }

src/Models/Cart.php

@@ -1034,6 +1034,22 @@ class Cart extends Model
             $is_booking = $cartable->purchasable->isBooking();
         }
 
+        // Price options (shop.cart.prices_as_options): a ProductPrice of a plain Product is
+        // stored as that Product with the chosen price_id, so the cart, the checkout line and
+        // the invoice show the product (and the option), not just the price row.
+        $itemPurchasable = $cartable;
+        $optionPrice = null;
+        if (
+            config('shop.cart.prices_as_options', false)
+            && $cartable instanceof ProductPrice
+            && $cartable->purchasable instanceof Product
+            && ! $is_pool
+            && ! $is_booking
+        ) {
+            $optionPrice = $cartable;
+            $itemPurchasable = $cartable->purchasable;
+        }
+
         if ($is_booking) {
             // Extract dates from parameters if not provided directly
             if (! $from && isset($parameters['from'])) {
@@ -1225,8 +1241,9 @@ class Cart extends Model
 
         // Check if item already exists in cart with same parameters, dates, AND price
         $existingItem = $this->items()
-            ->where('purchasable_id', $cartable->getKey())
-            ->where('purchasable_type', get_class($cartable))
+            ->where('purchasable_id', $itemPurchasable->getKey())
+            ->where('purchasable_type', get_class($itemPurchasable))
+            ->when($optionPrice, fn ($q) => $q->where('price_id', $optionPrice->getKey()))
             ->get()
             ->first(function ($item) use ($parameters, $from, $until, $cartable, $poolPriceId, $is_pool) {
                 $existingParams = is_array($item->parameters)
@@ -1400,8 +1417,8 @@ class Cart extends Model
 
         // Create new cart item
         $cartItem = $this->items()->create([
-            'purchasable_id' => $cartable->getKey(),
-            'purchasable_type' => get_class($cartable),
+            'purchasable_id' => $itemPurchasable->getKey(),
+            'purchasable_type' => get_class($itemPurchasable),
             'product_id' => ($cartable instanceof Product && $cartable->isPool() && $poolSingleItem) ? $poolSingleItem->id : null,
             'price_id' => $priceId,
             'quantity' => $quantity,

tests/Unit/Resources/CartItemResourceTest.php

@@ -0,0 +1,78 @@
+<?php
+
+namespace Blax\Shop\Tests\Unit\Resources;
+
+use Blax\Shop\Http\Resources\CartResource;
+use Blax\Shop\Models\Cart;
+use Blax\Shop\Models\Product;
+use Blax\Shop\Models\ProductPrice;
+use Blax\Shop\Tests\TestCase;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Http\Request;
+use PHPUnit\Framework\Attributes\Test;
+
+class CartItemResourceTest extends TestCase
+{
+    use RefreshDatabase;
+
+    #[Test]
+    public function items_carry_the_chosen_price_their_parameters_and_the_virtual_flag()
+    {
+        config(['shop.cart.prices_as_options' => true]);
+
+        $service = Product::factory()->create(['name' => 'Portrait', 'manage_stock' => false, 'virtual' => true]);
+        ProductPrice::factory()->create(['purchasable_id' => $service->id, 'purchasable_type' => Product::class, 'unit_amount' => 5000, 'is_default' => true, 'name' => 'A5']);
+        $a4 = ProductPrice::factory()->create(['purchasable_id' => $service->id, 'purchasable_type' => Product::class, 'unit_amount' => 7000, 'is_default' => false, 'name' => 'A4']);
+
+        $physical = Product::factory()->withPrices(unit_amount: 1000)->create(['name' => 'Keychain', 'manage_stock' => false]);
+
+        $cart = Cart::create(['currency' => 'EUR']);
+        $cart->addToCart($a4, 1, ['brief' => 'Two cats in space']);
+        $cart->addToCart($physical, 1);
+
+        $items = collect(CartResource::make($cart->fresh())->toArray(new Request)['items']->toArray(new Request))->keyBy(fn ($i) => $i['purchasable']['name']);
+
+        $this->assertSame($a4->id, $items['Portrait']['price_id']);
+        $this->assertSame('Two cats in space', ((array) $items['Portrait']['parameters'])['brief']);
+        $this->assertTrue($items['Portrait']['purchasable']['virtual']);
+        $this->assertSame(7000, $items['Portrait']['price']);
+
+        $this->assertSame([], (array) $items['Keychain']['parameters']);
+        $this->assertFalse($items['Keychain']['purchasable']['virtual']);
+    }
+
+    #[Test]
+    public function without_price_options_a_price_stays_the_purchasable()
+    {
+        $service = Product::factory()->create(['name' => 'Portrait', 'manage_stock' => false]);
+        $a4 = ProductPrice::factory()->create(['purchasable_id' => $service->id, 'purchasable_type' => Product::class, 'unit_amount' => 7000, 'is_default' => true, 'name' => 'A4']);
+
+        $cart = Cart::create(['currency' => 'EUR']);
+        $item = $cart->addToCart($a4, 1);
+
+        $this->assertSame(ProductPrice::class, $item->purchasable_type);
+        $this->assertSame($a4->id, $item->purchasable_id);
+    }
+
+    #[Test]
+    public function price_options_merge_only_with_the_same_option()
+    {
+        config(['shop.cart.prices_as_options' => true]);
+
+        $service = Product::factory()->create(['name' => 'Portrait', 'manage_stock' => false]);
+        $a5 = ProductPrice::factory()->create(['purchasable_id' => $service->id, 'purchasable_type' => Product::class, 'unit_amount' => 5000, 'is_default' => true, 'name' => 'A5']);
+        $a4 = ProductPrice::factory()->create(['purchasable_id' => $service->id, 'purchasable_type' => Product::class, 'unit_amount' => 7000, 'is_default' => false, 'name' => 'A4']);
+
+        $cart = Cart::create(['currency' => 'EUR']);
+        $cart->addToCart($a4, 1);
+        $cart->addToCart($a4, 1);
+        $cart->addToCart($a5, 1);
+
+        $items = $cart->fresh()->items;
+        $this->assertCount(2, $items);
+        $this->assertSame(2, (int) $items->firstWhere('price_id', $a4->id)->quantity);
+        $this->assertSame(14000, (int) $items->firstWhere('price_id', $a4->id)->subtotal);
+        $this->assertSame(5000, (int) $items->firstWhere('price_id', $a5->id)->price);
+        $this->assertTrue($items->every(fn ($i) => $i->purchasable_type === Product::class));
+    }
+}