stock check, variants in cart, variant buttons in product page

resources/views/checkout/partials/cart-error.blade.php

@@ -0,0 +1,9 @@
+{{--
+    Shared error slot for any host wrapping cart-body in a bbk-cart controller
+    instance (the drawer, and the checkout page's own order summary) —
+    bbk-cart-controller.js#showError() writes into whichever one is present.
+    Without this element in a given host, a rejected quantity update (e.g.
+    over stock) still gets rejected server-side, but the shopper never sees
+    why.
+--}}
+<p class="bbk-cart-error" data-bbk-cart-target="error" hidden role="alert"></p>

resources/views/checkout/partials/cart-line.blade.php

@@ -7,7 +7,11 @@
     $variant = $line->purchasable;
     $product = $variant?->product;
     $name = $product?->translateAttribute('name') ?? $variant?->sku ?? '—';
-    $thumb = $product?->getThumbnailImage() ?: null;
+    // The variant's own image (falls back to the product's thumbnail
+    // internally — see ProductVariant::getThumbnail()) — the specific option
+    // the shopper picked, not just the product in general.
+    $thumb = $variant?->getThumbnailImage() ?: null;
+    $variantLabel = $variant?->getOption();
 @endphp
 
 <li class="bbk-cart-item" data-bbk-line-id="{{ $line->id }}">
@@ -19,6 +23,9 @@
 
     <div class="bbk-cart-item-detail">
         <p class="bbk-cart-item-title">{{ $name }}</p>
+        @if ($variantLabel)
+            <p class="bbk-cart-item-variant">{{ $variantLabel }}</p>
+        @endif
         <p class="bbk-cart-item-unit">{{ $line->unitPrice?->formatted() }}</p>
 
         <form
@@ -44,6 +51,7 @@ class="bbk-cart-qty-btn"
                 inputmode="numeric"
                 class="bbk-cart-qty-input"
                 data-action="change->bbk-cart#submit"
+                data-bbk-cart-confirmed-quantity="{{ $line->quantity }}"
                 aria-label="{{ __('checkout.cart.quantity') }}"
             >