refactor(cart): update CartItemResource to serialize only selected variant and remove unused variant data

app/Domains/Cart/Resources/CartItemResource.php

@@ -4,7 +4,6 @@ namespace App\Domains\Cart\Resources;
 
 use App\Domains\Cart\Models\CartItem;
 use App\Domains\Catalog\Enums\InventoryPolicy;
-use App\Domains\Catalog\Models\Variant;
 use Illuminate\Http\Request;
 use Illuminate\Http\Resources\Json\JsonResource;
 
@@ -38,16 +37,14 @@ class CartItemResource extends JsonResource
             'product' => $selectedItem === null ? null : [
                 'nombre' => $selectedItem->getName(),
                 'imagen' => $imageUrl,
-                'variants' => $this->catalogItem->visibleVariants($this->variant_id)
-                    ->map(fn (Variant $variant): array => [
-                        'id' => $variant->id,
-                        'precio' => $this->formatMoney($variant->getPrice()),
-                        'stock_tecnico' => $this->catalogItem->inventory_policy === InventoryPolicy::Unlimited
-                            ? null
-                            : $variant->inventory->availableStock(),
-                        'values' => $variant->selectorOptions($this->catalogItem->itemAttributes),
-                    ])
-                    ->values(),
+                'variant' => $this->variant === null ? null : [
+                    'id' => $this->variant->id,
+                    'precio' => $this->formatMoney($this->variant->getPrice()),
+                    'stock_tecnico' => $this->catalogItem->inventory_policy === InventoryPolicy::Unlimited
+                        ? null
+                        : $this->variant->inventory->availableStock(),
+                    'values' => $this->variant->selectorOptions($this->catalogItem->itemAttributes),
+                ],
             ],
         ];
     }

app/Domains/Cart/Services/CartService.php

@@ -108,10 +108,6 @@ class CartService
             'items.catalogItem.attachments',
             'items.catalogItem.inventory',
             'items.catalogItem.itemAttributes.attribute',
-            'items.catalogItem.variants.inventory',
-            'items.catalogItem.variants.definitions.itemAttribute.attribute.options',
-            'items.catalogItem.variants.eventDates',
-            'items.catalogItem.variants.eventDate',
             'items.variant.attachments',
             'items.variant.inventory',
             'items.variant.definitions.itemAttribute.attribute.options',

app/Domains/Cart/documentacion/README.md

@@ -25,7 +25,7 @@ Bajo `/tenants/{tenant:codigo}`:
 
 ## Contratos
 
-`AddCartItemRequest` y `UpdateCartItemQuantityRequest` validan selección y cantidad. `CartResource` y `CartItemResource` estabilizan la respuesta pública.
+`AddCartItemRequest` y `UpdateCartItemQuantityRequest` validan selección y cantidad. `CartResource` y `CartItemResource` estabilizan la respuesta pública. Cada ítem serializa únicamente su variante seleccionada en `product.variant`; las variantes alternativas no forman parte de la respuesta del carrito.
 
 ## Dependencias y reglas
 

tests/Feature/Cart/CartControllerTest.php

@@ -276,11 +276,6 @@ class CartControllerTest extends TestCase
             'inventory_id' => $secondInventory->id,
             'precio' => '20.00',
         ]);
-        $unavailableInventory = Inventory::query()->create(['real_stock' => 0]);
-        $unavailableVariant = $item->variants()->create([
-            'inventory_id' => $unavailableInventory->id,
-            'precio' => '25.00',
-        ]);
         $createResponse = $this->postJson('/api/tenants/acme/cart/items', [
             'catalog_item_id' => $item->id,
             'variant_id' => $firstVariant->id,
@@ -301,11 +296,9 @@ class CartControllerTest extends TestCase
             ->assertOk()
             ->assertJsonPath('data.items.0.variant_id', $secondVariant->id)
             ->assertJsonPath('data.items.0.precio_unitario', '20.00')
-            ->assertJsonCount(2, 'data.items.0.product.variants')
-            ->assertJsonPath('data.items.0.product.variants.0.id', $firstVariant->id)
-            ->assertJsonPath('data.items.0.product.variants.1.id', $secondVariant->id)
-            ->assertJsonPath('data.items.0.product.variants.1.stock_tecnico', 0)
-            ->assertJsonMissing(['id' => $unavailableVariant->id, 'stock_tecnico' => 0]);
+            ->assertJsonPath('data.items.0.product.variant.id', $secondVariant->id)
+            ->assertJsonPath('data.items.0.product.variant.stock_tecnico', 0)
+            ->assertJsonMissingPath('data.items.0.product.variants');
 
         $this->assertDatabaseHas('inventories', [
             'id' => $firstVariant->inventory_id,