prevent checkout with unavailable product variants

- Include is_available flag in hydrated cart items
- Show unavailable message on cart items and product page
- Block add-to-cart for unavailable variants
- Redirect back to cart with error if checkout has unavailable items

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

assets/css/shop/components.css

@@ -781,6 +781,15 @@
     font-weight: 600;
   }
 
+  /* ── Unavailable message ── */
+
+  .variant-unavailable-msg {
+    color: var(--t-sale-color);
+    font-size: var(--t-text-small);
+    font-weight: 500;
+    margin-bottom: 1rem;
+  }
+
   /* ── Add to cart ── */
 
   .atc-wrap {
@@ -1709,6 +1718,13 @@
     margin: 0;
   }
 
+  .cart-item-unavailable {
+    font-size: var(--t-text-caption);
+    color: var(--t-sale-color);
+    font-weight: 500;
+    margin: 0.25rem 0 0;
+  }
+
   .cart-item-actions {
     display: flex;
     justify-content: space-between;

lib/berrypod/cart.ex

@@ -132,7 +132,8 @@ defmodule Berrypod.Cart do
               variant: format_variant_options(variant.options),
               price: variant.price,
               quantity: quantity,
-              image: variant_image_url(variant.product)
+              image: variant_image_url(variant.product),
+              is_available: variant.is_available
             }
         end
       end)

lib/berrypod_web/components/shop_components/cart.ex

@@ -212,6 +212,10 @@ defmodule BerrypodWeb.ShopComponents.Cart do
           </p>
         <% end %>
 
+        <p :if={Map.get(@item, :is_available) == false} class="cart-item-unavailable">
+          This item is currently unavailable
+        </p>
+
         <div class="cart-item-actions">
           <%= if @show_quantity_controls do %>
             <form

lib/berrypod_web/controllers/checkout_controller.ex

@@ -16,11 +16,18 @@ defmodule BerrypodWeb.CheckoutController do
       cart_items = Cart.get_from_session(get_session(conn))
       hydrated = Cart.hydrate(cart_items)
 
-      if hydrated == [] do
+      cond do
+        hydrated == [] ->
           conn
           |> put_flash(:error, "Your basket is empty")
           |> redirect(to: ~p"/cart")
-      else
+
+        Enum.any?(hydrated, &(&1.is_available == false)) ->
+          conn
+          |> put_flash(:error, "Some items in your basket are no longer available")
+          |> redirect(to: ~p"/cart")
+
+        true ->
           track_checkout_start(conn)
           create_checkout(conn, hydrated)
       end

lib/berrypod_web/live/shop/pages/product.ex

@@ -90,7 +90,7 @@ defmodule BerrypodWeb.Shop.Pages.Product do
   def handle_event("add_to_cart", _params, socket) do
     variant = socket.assigns.selected_variant
 
-    if variant do
+    if variant && variant.is_available do
       cart = Cart.add_item(socket.assigns.raw_cart, variant.id, socket.assigns.quantity)
 
       if socket.assigns[:analytics_visitor_hash] do

lib/berrypod_web/page_renderer.ex

@@ -553,7 +553,18 @@ defmodule BerrypodWeb.PageRenderer do
             </div>
 
             <.quantity_selector quantity={assigns[:quantity] || 1} in_stock={@product.in_stock} />
-            <.add_to_cart_button mode={@mode} />
+
+            <p
+              :if={assigns[:selected_variant] && !assigns[:selected_variant].is_available}
+              class="variant-unavailable-msg"
+            >
+              This option is currently unavailable
+            </p>
+
+            <.add_to_cart_button
+              mode={@mode}
+              disabled={assigns[:selected_variant] && !assigns[:selected_variant].is_available}
+            />
           </form>
         </div>
       </div>