diff --git a/lang/en/auth.php b/lang/en/auth.php
new file mode 100644
index 0000000..25c2d0e
--- /dev/null
+++ b/lang/en/auth.php
@@ -0,0 +1,6 @@
+<?php
+
+return [
+    'invalid_credentials' => 'Invalid credentials.',
+    'login_ok' => 'Signed in.',
+];
diff --git a/lang/en/cart.php b/lang/en/cart.php
new file mode 100644
index 0000000..5b69740
--- /dev/null
+++ b/lang/en/cart.php
@@ -0,0 +1,15 @@
+<?php
+
+return [
+    'session_updated' => 'Cart updated.',
+    'not_found' => 'That item could not be found.',
+    'item_not_found' => 'That cart item could not be found.',
+    'out_of_stock' => 'Not enough stock available.',
+    'add_failed' => 'Could not add the item to your cart.',
+    'added' => 'Added to cart.',
+    'removed' => 'Removed from cart.',
+    'converted' => 'This cart has already been checked out.',
+    'checkout_failed' => 'Checkout could not be started.',
+    'checkout_unavailable' => 'Checkout is currently unavailable.',
+    'checkout_created' => 'Redirecting to payment.',
+];
diff --git a/phpunit.xml b/phpunit.xml
index 14f79ae..a9acd87 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -22,6 +22,11 @@
         </include>
         <exclude>
             <directory>./src/database</directory>
+            <!-- WebSocket controllers extend blax-software/laravel-websockets, a
+                 soft (suggest) dependency absent from the package's own test env.
+                 Their logic lives in the covered CartService; exclude the thin
+                 glue so coverage runs don't try to reflect the missing base class. -->
+            <directory>./src/Websocket</directory>
         </exclude>
     </source>
     <coverage includeUncoveredFiles="true" />
diff --git a/src/Facades/Cart.php b/src/Facades/Cart.php
index 471c24a..5ac1c32 100644
--- a/src/Facades/Cart.php
+++ b/src/Facades/Cart.php
@@ -11,6 +11,9 @@ use Illuminate\Support\Facades\Facade;
  * @method static \Blax\Shop\Models\Cart guest(string|null $sessionId = null)
  * @method static \Blax\Shop\Models\Cart forUser(\Illuminate\Contracts\Auth\Authenticatable $user)
  * @method static \Blax\Shop\Models\Cart|null find(string $cartId)
+ * @method static \Blax\Shop\Models\Cart adopt(string|null $cartId, string $sessionId)
+ * @method static \Blax\Shop\Models\Cart mergeGuestIntoUser(\Blax\Shop\Models\Cart $guestCart, \Illuminate\Contracts\Auth\Authenticatable $user)
+ * @method static string|null|false checkoutSessionLink(\Blax\Shop\Models\Cart|null $cart = null, array $options = [], string|null $url = null)
  * @method static \Blax\Shop\Models\CartItem add(\Illuminate\Database\Eloquent\Model $product, int $quantity = 1, array $parameters = [])
  * @method static \Blax\Shop\Models\CartItem|true remove(\Illuminate\Database\Eloquent\Model $product, int $quantity = 1, array $parameters = [])
  * @method static \Blax\Shop\Models\CartItem update(\Blax\Shop\Models\CartItem $cartItem, int $quantity)
diff --git a/src/Http/Resources/CartItemResource.php b/src/Http/Resources/CartItemResource.php
new file mode 100644
index 0000000..f8a8cbb
--- /dev/null
+++ b/src/Http/Resources/CartItemResource.php
@@ -0,0 +1,90 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Blax\Shop\Http\Resources;
+
+use Illuminate\Http\Request;
+use Illuminate\Http\Resources\Json\JsonResource;
+
+/**
+ * A single line in {@see CartResource}. Money is integer minor units (cents).
+ *
+ * `purchasable` is a compact summary (id/name/slug/type/image) so a cart drawer
+ * can render without a second round-trip. The image lookup is best-effort: it
+ * only resolves when the purchasable exposes a laravel-files `files()` relation,
+ * and never throws if the file layer is absent.
+ *
+ * @mixin \Blax\Shop\Models\CartItem
+ */
+class CartItemResource extends JsonResource
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function toArray(Request $request): array
+    {
+        $purchasable = $this->purchasable;
+
+        return [
+            'id' => $this->id,
+            'quantity' => (int) $this->quantity,
+            'price' => $this->price === null ? null : (int) $this->price,
+            'regular_price' => $this->regular_price === null ? null : (int) $this->regular_price,
+            'subtotal' => $this->subtotal === null ? null : (int) $this->subtotal,
+            'currency' => $this->currency,
+            'purchasable' => $purchasable ? [
+                'id' => $purchasable->getKey(),
+                'name' => $purchasable->name ?? null,
+                'slug' => $purchasable->slug ?? null,
+                'type' => $this->purchasableType($purchasable),
+                'image' => $this->resolveImage($purchasable),
+            ] : null,
+        ];
+    }
+
+    /**
+     * Stringify a product type enum (or pass through a scalar) without assuming
+     * the purchasable is a Product.
+     */
+    private function purchasableType(mixed $purchasable): ?string
+    {
+        $type = $purchasable->type ?? null;
+
+        if ($type === null) {
+            return null;
+        }
+
+        return $type instanceof \BackedEnum ? (string) $type->value : (string) $type;
+    }
+
+    /**
+     * Best-effort primary image URL via the laravel-files `files()` relation.
+     * Prefers a single-slot image (thumbnail/cover/icon), then the first
+     * gallery/any file. Returns null and swallows errors when files aren't wired.
+     */
+    private function resolveImage(mixed $purchasable): ?string
+    {
+        if (! is_object($purchasable) || ! method_exists($purchasable, 'files')) {
+            return null;
+        }
+
+        try {
+            $files = $purchasable->files()->get();
+
+            if ($files->isEmpty()) {
+                return null;
+            }
+
+            $preferred = $files->first(function ($file) {
+                $as = $file->pivot->as ?? null;
+
+                return in_array($as, ['thumbnail', 'cover', 'icon', 'banner', 'logo'], true);
+            });
+
+            return ($preferred ?? $files->first())->url ?? null;
+        } catch (\Throwable) {
+            return null;
+        }
+    }
+}
diff --git a/src/Http/Resources/CartResource.php b/src/Http/Resources/CartResource.php
new file mode 100644
index 0000000..556d1fe
--- /dev/null
+++ b/src/Http/Resources/CartResource.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Blax\Shop\Http\Resources;
+
+use Illuminate\Http\Request;
+use Illuminate\Http\Resources\Json\JsonResource;
+
+/**
+ * Stable storefront wire shape for a Cart.
+ *
+ * This is the payload the cart-driving controllers (WebSocket or HTTP) hand a
+ * frontend after every mutation. All money is integer MINOR units (cents) plus
+ * an explicit ISO-4217 `currency` — never inferred, never pre-divided — so the
+ * client owns formatting. Kept deliberately flat and presentation-agnostic;
+ * apps that need extra fields extend this resource.
+ *
+ * @mixin \Blax\Shop\Models\Cart
+ */
+class CartResource extends JsonResource
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function toArray(Request $request): array
+    {
+        $items = $this->items()->with('purchasable')->get();
+
+        return [
+            'id' => $this->id,
+            'currency' => $this->currency ?? config('shop.currency'),
+            // Sum of line subtotals in minor units (cents).
+            'total' => (int) $items->sum('subtotal'),
+            'item_count' => (int) $items->sum('quantity'),
+            'is_converted' => $this->isConverted(),
+            'is_ready_to_checkout' => $this->is_ready_to_checkout,
+            'items' => CartItemResource::collection($items),
+        ];
+    }
+}
diff --git a/src/Services/CartService.php b/src/Services/CartService.php
index 4fab22d..3d22e7a 100644
--- a/src/Services/CartService.php
+++ b/src/Services/CartService.php
@@ -112,6 +112,51 @@ class CartService
         return $cart;
     }
 
+    /**
+     * Merge a guest cart into a user's current cart at login.
+     *
+     * laravel-shop had `shop.cart.merge_on_login` in config but no code ever
+     * honoured it: `current()` merely *forgets* a guest session cart when a user
+     * authenticates, it never moves the items over. This closes that gap.
+     *
+     * Items are RE-PARENTED (their cart_id is repointed) rather than re-added,
+     * which preserves each line's already-claimed stock, resolved price and
+     * booking dates instead of re-running add-to-cart side effects (and the
+     * stock claim) a second time. The emptied guest cart is detached from its
+     * session so it can't be re-adopted.
+     *
+     * Guarded: a cart that is the user's own cart, already owned by a customer,
+     * or already converted, is returned untouched.
+     *
+     * @param Cart            $guestCart Guest cart to drain.
+     * @param Authenticatable $user      User to receive the items (needs HasCart).
+     * @return Cart The user's current cart.
+     */
+    public function mergeGuestIntoUser(Cart $guestCart, Authenticatable $user): Cart
+    {
+        if (!method_exists($user, 'currentCart')) {
+            throw new \InvalidArgumentException('User model must have shopping capabilities (use the HasCart / HasShoppingCapabilities trait).');
+        }
+
+        $userCart = $user->currentCart();
+
+        // Nothing to do: same cart, or the source isn't a drainable guest cart.
+        if ($guestCart->is($userCart) || $guestCart->customer_id || $guestCart->isConverted()) {
+            return $userCart;
+        }
+
+        $moved = $guestCart->items()->update(['cart_id' => $userCart->getKey()]);
+
+        if ($moved > 0) {
+            $userCart->touchActivity();
+        }
+
+        // Detach the emptied guest cart so adopt()/guest() can't resurrect it.
+        $guestCart->update(['session_id' => 'merged_' . $guestCart->getKey()]);
+
+        return $userCart->fresh();
+    }
+
     /**
      * Find cart by ID
      *
@@ -123,6 +168,55 @@ class CartService
         return Cart::find($cartId);
     }
 
+    /**
+     * Resolve the guest cart for a connection, optionally adopting a cart the
+     * client already holds an id for, and re-bind it to this connection so the
+     * cart "follows" the socket across reconnects.
+     *
+     * This is the server-side counterpart to a stateless client (e.g. a
+     * WebSocket connection) that persists its cart id locally and re-sends it
+     * on every message: pass that id as $cartId and the connection's stable id
+     * (socket id / session id) as $sessionId.
+     *
+     *  - Unknown / missing id, or a cart already converted to an order → a fresh
+     *    guest cart bound to $sessionId.
+     *  - A guest cart bound to a different session → re-bound to $sessionId
+     *    (and any stale guest cart already on $sessionId is removed first, so a
+     *    connection never accumulates orphan guest carts).
+     *  - A cart already owned by a customer is never stolen — it is returned as-is.
+     *
+     * @param string|null $cartId    Cart id the client claims to hold, if any.
+     * @param string      $sessionId Stable connection identifier to bind to.
+     * @return Cart
+     */
+    public function adopt(?string $cartId, string $sessionId): Cart
+    {
+        /** @var class-string<Cart> $cartModel */
+        $cartModel = config('shop.models.cart', Cart::class);
+
+        $cart = ($cartId !== null && $cartId !== '')
+            ? $cartModel::find($cartId)
+            : null;
+
+        // Unknown id, or a cart that's already an order: start fresh.
+        if (! $cart || $cart->isConverted()) {
+            return $this->guest($sessionId);
+        }
+
+        // Re-bind a guest cart to this connection. Never steal a customer's cart.
+        if (! $cart->customer_id && $cart->session_id !== $sessionId) {
+            $cartModel::query()
+                ->where('session_id', $sessionId)
+                ->whereNull('customer_id')
+                ->whereKeyNot($cart->getKey())
+                ->delete();
+
+            $cart->update(['session_id' => $sessionId]);
+        }
+
+        return $cart;
+    }
+
     /**
      * Add item to current cart (from session or authenticated user)
      * For guests without session, use guest() first: Cart::guest()->add($product)
@@ -230,6 +324,27 @@ class CartService
         return $cart->checkout();
     }
 
+    /**
+     * Create (or reuse) a Stripe Checkout Session for a cart and return its
+     * hosted-payment URL. Facade passthrough to Cart::checkoutSessionLink() so
+     * callers can drive Stripe checkout straight off the facade without reaching
+     * into the model — the shape a WS/HTTP controller wants (`{ redirect: url }`).
+     *
+     * Unlike checkout(), this works for GUEST carts (Stripe collects the buyer),
+     * so no authenticated user is required.
+     *
+     * @param Cart|null   $cart    Cart to check out; defaults to current().
+     * @param array       $options Extra Stripe Checkout Session options.
+     * @param string|null $url     Return/success base URL.
+     * @return string|null|false URL string, null if Stripe disabled / no session, false on error.
+     */
+    public function checkoutSessionLink(?Cart $cart = null, array $options = [], ?string $url = null): string|null|false
+    {
+        $cart = $cart ?? $this->current();
+
+        return $cart->checkoutSessionLink($options, $url);
+    }
+
     /**
      * Get total for a cart
      * If no cart provided, gets current user's cart total
diff --git a/src/ShopServiceProvider.php b/src/ShopServiceProvider.php
index 39e51bd..86aa85d 100644
--- a/src/ShopServiceProvider.php
+++ b/src/ShopServiceProvider.php
@@ -43,6 +43,8 @@ class ShopServiceProvider extends ServiceProvider
     {
         $this->offerPublishing();
 
+        $this->loadTranslationsFrom(__DIR__ . '/../lang', 'shop');
+
         $this->registerMigrations();
 
         $this->registerSubscriptionModels();
diff --git a/src/Websocket/Controllers/AuthController.php b/src/Websocket/Controllers/AuthController.php
new file mode 100644
index 0000000..0ce8914
--- /dev/null
+++ b/src/Websocket/Controllers/AuthController.php
@@ -0,0 +1,135 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Blax\Shop\Websocket\Controllers;
+
+use Blax\Shop\Facades\Cart as CartFacade;
+use Illuminate\Support\Facades\Auth;
+
+/**
+ * Reusable storefront auth over the Blax WebSocket bridge (Sanctum PAT).
+ *
+ * Expose in a consuming app with a one-line stub:
+ *
+ *     class AuthController extends \Blax\Shop\Websocket\Controllers\AuthController {}
+ *
+ * `login` authenticates by email+password OR by an existing bearer token, issues
+ * a Sanctum personal access token the client stores and re-sends as `authtoken`,
+ * and MERGES the connection's guest cart into the user's cart (closing the
+ * shop.cart.merge_on_login gap via CartService::mergeGuestIntoUser). `me`
+ * self-heals the connection from a bearer token and seeds the per-socket auth
+ * cache so subsequent need_auth controllers resolve the user.
+ *
+ * Requires Sanctum on the consuming app (guarded) + a User model using
+ * HasApiTokens and the shop HasCart/HasShoppingCapabilities trait.
+ */
+class AuthController extends \BlaxSoftware\LaravelWebSockets\Websocket\Controller
+{
+    public $need_auth = false;
+
+    public function login()
+    {
+        $requestData = request()->all();
+
+        if (! empty($requestData['token'])) {
+            $data = request()->validate([
+                'token' => 'required|string',
+                'email' => 'sometimes',
+                'password' => 'sometimes',
+            ]);
+        } else {
+            $data = request()->validate([
+                'email' => 'required|email',
+                'password' => 'required|string',
+            ]);
+        }
+
+        $token = null;
+
+        // Path 1: validate an existing bearer token.
+        if (! empty($data['token']) && $this->sanctumAvailable()) {
+            $tokenable = optional(\Laravel\Sanctum\PersonalAccessToken::findToken($data['token']))->tokenable;
+
+            if ($tokenable) {
+                Auth::login($tokenable);
+                $token = $data['token'];
+            }
+        }
+
+        // Path 2: email + password → new token.
+        if (! Auth::check() && isset($data['email'], $data['password']) && Auth::attempt($data)) {
+            $user = Auth::user();
+
+            if (method_exists($user, 'createToken')) {
+                $token = explode('|', $user->createToken('authtoken')->plainTextToken)[1] ?? null;
+            }
+        }
+
+        if (! Auth::check()) {
+            return $this->error(__('shop::auth.invalid_credentials'));
+        }
+
+        $user = Auth::user();
+
+        $this->seedSocketAuthCache();
+        $this->mergeGuestCart($user);
+
+        return $this->success([
+            'message' => __('shop::auth.login_ok'),
+            'user' => $user,
+            'token' => $token,
+        ]);
+    }
+
+    public function me()
+    {
+        $token = request('authtoken') ?? request('token');
+
+        if ($token && ! Auth::check() && $this->sanctumAvailable()) {
+            $tokenable = optional(\Laravel\Sanctum\PersonalAccessToken::findToken($token))->tokenable;
+
+            if ($tokenable) {
+                Auth::login($tokenable);
+            }
+        }
+
+        if (Auth::check()) {
+            $this->seedSocketAuthCache();
+        }
+
+        return $this->success(['user' => Auth::user()]);
+    }
+
+    /**
+     * Merge this connection's guest cart into the just-authenticated user's cart.
+     */
+    protected function mergeGuestCart($user): void
+    {
+        try {
+            $guest = CartFacade::guest($this->connection->socketId);
+            CartFacade::mergeGuestIntoUser($guest, $user);
+        } catch (\Throwable) {
+            // A cart merge must never block login.
+        }
+    }
+
+    /**
+     * Cache {id,type} under socket_<id> so subsequent need_auth controllers on
+     * this connection can resolve the user without another token round-trip.
+     */
+    protected function seedSocketAuthCache(): void
+    {
+        $key = 'socket_' . $this->connection->socketId;
+        cache()->forget($key);
+        cache()->remember($key, 60 * 15, fn () => [
+            'id' => Auth::id(),
+            'type' => Auth::user() ? get_class(Auth::user()) : null,
+        ]);
+    }
+
+    protected function sanctumAvailable(): bool
+    {
+        return class_exists(\Laravel\Sanctum\PersonalAccessToken::class);
+    }
+}
diff --git a/src/Websocket/Controllers/CartController.php b/src/Websocket/Controllers/CartController.php
new file mode 100644
index 0000000..f734d91
--- /dev/null
+++ b/src/Websocket/Controllers/CartController.php
@@ -0,0 +1,212 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Blax\Shop\Websocket\Controllers;
+
+use Blax\Shop\Enums\CartStatus;
+use Blax\Shop\Exceptions\NotEnoughStockException;
+use Blax\Shop\Facades\Cart as CartFacade;
+use Blax\Shop\Http\Resources\CartResource;
+
+/**
+ * Reusable storefront cart controller over the Blax WebSocket bridge.
+ *
+ * Ship-once, use-everywhere: a consuming app exposes it with a one-line stub in
+ * app/Websocket/Controllers/ (the resolver only scans that namespace + this
+ * package's, and resolves INHERITED methods):
+ *
+ *     class CartController extends \Blax\Shop\Websocket\Controllers\CartController {}
+ *
+ * The cart "follows" the socket: booted() adopts the client-held cart id and
+ * re-binds it to this connection (see CartService::adopt), so every cart.*
+ * method operates on the right guest cart without an account. All handlers reply
+ * with the {@see CartResource} wire shape.
+ *
+ * Requires blax-software/laravel-websockets (soft dependency — this class is only
+ * ever loaded inside a WS runtime, so the package installs fine without it).
+ */
+class CartController extends \BlaxSoftware\LaravelWebSockets\Websocket\Controller
+{
+    /** Guest storefront: no account required. */
+    public $need_auth = false;
+
+    /** @var \Blax\Shop\Models\Cart */
+    protected $cart = null;
+
+    /**
+     * Resolve + re-bind this connection's cart before every cart.* method.
+     */
+    public function booted()
+    {
+        $cartId = request('cart_id');
+        $cartId = is_string($cartId) && $cartId !== '' ? $cartId : null;
+
+        $this->cart = CartFacade::adopt($cartId, $this->connection->socketId);
+    }
+
+    /**
+     * Echo the (already-adopted) cart back to the client. The frontend persists
+     * `cart.id` locally and re-sends it as `cart_id` on subsequent calls.
+     */
+    public function setCart()
+    {
+        return $this->success([
+            'message' => __('shop::cart.session_updated'),
+            'cart' => CartResource::make($this->cart),
+        ]);
+    }
+
+    /**
+     * Add a purchasable to the cart. `cart_item_id` is overloaded (frontend
+     * contract): it may be a CartItem id, a ProductPrice id, or a Product id.
+     */
+    public function add()
+    {
+        $data = request()->validate([
+            'cart_item_id' => 'sometimes|string',
+            'quantity' => 'required|integer|min:1',
+        ]);
+
+        $addable = $this->resolveAddable($data['cart_item_id'] ?? null);
+
+        if (! $addable) {
+            return $this->error(['message' => __('shop::cart.not_found')]);
+        }
+
+        $this->alignCartCurrency($addable);
+
+        try {
+            $this->cart->addToCart(cartable: $addable, quantity: $data['quantity']);
+        } catch (NotEnoughStockException) {
+            return $this->error(['message' => __('shop::cart.out_of_stock')]);
+        } catch (\Throwable $e) {
+            return $this->error([
+                'message' => __('shop::cart.add_failed'),
+                'detail' => $e->getMessage(),
+            ]);
+        }
+
+        return $this->success([
+            'message' => __('shop::cart.added'),
+            'cart' => CartResource::make($this->cart->fresh()),
+        ]);
+    }
+
+    /**
+     * Remove (or decrement) a line by cart item id.
+     */
+    public function remove()
+    {
+        $cartItemModel = config('shop.models.cart_item');
+
+        $data = request()->validate([
+            'cart_item_id' => 'required|string',
+            'quantity' => 'required|integer|min:1',
+        ]);
+
+        $item = $cartItemModel::find($data['cart_item_id']);
+
+        if (! $item) {
+            return $this->error(['message' => __('shop::cart.item_not_found')]);
+        }
+
+        $this->cart->removeFromCart(cartable: $item, quantity: $data['quantity']);
+
+        return $this->success([
+            'message' => __('shop::cart.removed'),
+            'cart' => CartResource::make($this->cart->fresh()),
+        ]);
+    }
+
+    /**
+     * Return the current cart.
+     */
+    public function show()
+    {
+        return $this->success(CartResource::make($this->cart));
+    }
+
+    /**
+     * Return the cart, streaming a conversion frame if it has already become an
+     * order (e.g. the client is polling after a Stripe redirect-back).
+     */
+    public function checkoutDetails()
+    {
+        if ($this->cart->isConverted()) {
+            $this->progress([
+                'message' => __('shop::cart.converted'),
+                'status' => CartStatus::CONVERTED,
+                'order' => $this->cart->order,
+            ]);
+        }
+
+        return $this->success(CartResource::make($this->cart));
+    }
+
+    /**
+     * Create a Stripe Checkout Session and hand back its hosted-payment URL.
+     */
+    public function checkout()
+    {
+        $data = request()->validate([
+            'url' => 'sometimes|url',
+        ]);
+
+        try {
+            $url = CartFacade::checkoutSessionLink($this->cart, [], $data['url'] ?? null);
+        } catch (\Throwable $e) {
+            return $this->error([
+                'message' => __('shop::cart.checkout_failed'),
+                'detail' => $e->getMessage(),
+            ]);
+        }
+
+        if (! $url) {
+            return $this->error(['message' => __('shop::cart.checkout_unavailable')]);
+        }
+
+        return $this->success([
+            'message' => __('shop::cart.checkout_created'),
+            'redirect' => $url,
+        ]);
+    }
+
+    /**
+     * Resolve the overloaded `cart_item_id` into a purchasable (CartItem's
+     * purchasable, else a ProductPrice, else a Product).
+     */
+    protected function resolveAddable(?string $id)
+    {
+        if (! $id) {
+            return null;
+        }
+
+        $cartItemModel = config('shop.models.cart_item');
+        $productPriceModel = config('shop.models.product_price');
+        $productModel = config('shop.models.product');
+
+        $addable = $cartItemModel::find($id)?->purchasable;
+        $addable ??= $productPriceModel::find($id);
+        $addable ??= $productModel::find($id);
+
+        return $addable;
+    }
+
+    /**
+     * Keep the cart's currency in step with the purchasable being added so a
+     * mixed-currency cart can't form.
+     */
+    protected function alignCartCurrency($addable): void
+    {
+        $productPriceModel = config('shop.models.product_price');
+
+        $currency = $addable instanceof $productPriceModel
+            ? $addable->currency
+            : $addable->defaultPrice()->first()?->currency;
+
+        if ($currency && $currency !== $this->cart->currency) {
+            $this->cart->update(['currency' => $currency]);
+        }
+    }
+}
diff --git a/tests/Unit/Cart/CartAdoptMergeTest.php b/tests/Unit/Cart/CartAdoptMergeTest.php
new file mode 100644
index 0000000..46098fa
--- /dev/null
+++ b/tests/Unit/Cart/CartAdoptMergeTest.php
@@ -0,0 +1,123 @@
+<?php
+
+namespace Blax\Shop\Tests\Unit\Cart;
+
+use Blax\Shop\Facades\Cart as CartFacade;
+use Blax\Shop\Models\Cart;
+use Blax\Shop\Models\Product;
+use Blax\Shop\Tests\TestCase;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use PHPUnit\Framework\Attributes\Test;
+use Workbench\App\Models\User;
+
+/**
+ * Covers the storefront primitives added for WS-first shops:
+ * CartService::adopt() (connection cart binding) and
+ * CartService::mergeGuestIntoUser() (the previously-dead merge_on_login gap).
+ */
+class CartAdoptMergeTest extends TestCase
+{
+    use RefreshDatabase;
+
+    #[Test]
+    public function adopt_without_id_returns_a_guest_cart_bound_to_the_session()
+    {
+        $cart = CartFacade::adopt(null, 'socket-A');
+
+        $this->assertInstanceOf(Cart::class, $cart);
+        $this->assertSame('socket-A', $cart->session_id);
+        $this->assertNull($cart->customer_id);
+    }
+
+    #[Test]
+    public function adopt_with_unknown_id_falls_back_to_a_fresh_guest_cart()
+    {
+        $cart = CartFacade::adopt('00000000-0000-0000-0000-000000000000', 'socket-A');
+
+        $this->assertSame('socket-A', $cart->session_id);
+    }
+
+    #[Test]
+    public function adopt_rebinds_a_guest_cart_to_the_new_session_and_clears_stale_ones()
+    {
+        $held = Cart::factory()->create(['session_id' => 'socket-old', 'customer_id' => null]);
+        $stale = Cart::factory()->create(['session_id' => 'socket-B', 'customer_id' => null]);
+
+        $adopted = CartFacade::adopt($held->id, 'socket-B');
+
+        $this->assertTrue($held->is($adopted));
+        $this->assertSame('socket-B', $adopted->fresh()->session_id);
+        // The stale guest cart already sitting on socket-B is removed.
+        $this->assertNull(Cart::find($stale->id));
+    }
+
+    #[Test]
+    public function adopt_never_steals_a_customer_owned_cart()
+    {
+        $user = User::factory()->create();
+        $owned = Cart::factory()->create([
+            'session_id' => 'socket-old',
+            'customer_id' => $user->id,
+            'customer_type' => get_class($user),
+        ]);
+
+        $adopted = CartFacade::adopt($owned->id, 'socket-Z');
+
+        $this->assertTrue($owned->is($adopted));
+        // Untouched: still owned, session not rebound.
+        $this->assertSame('socket-old', $adopted->fresh()->session_id);
+    }
+
+    #[Test]
+    public function merge_moves_guest_items_onto_the_user_cart_and_retires_the_guest()
+    {
+        $user = User::factory()->create();
+        $product = Product::factory()->withPrices()->create(['manage_stock' => false]);
+
+        $guest = Cart::factory()->create(['session_id' => 'socket-A', 'customer_id' => null]);
+        $guest->addToCart($product, 2);
+
+        $userCart = CartFacade::mergeGuestIntoUser($guest, $user);
+
+        $this->assertSame(2, $userCart->items()->sum('quantity'));
+        $this->assertSame(0, $guest->fresh()->items()->count());
+        $this->assertStringStartsWith('merged_', $guest->fresh()->session_id);
+    }
+
+    #[Test]
+    public function merge_is_a_noop_for_a_converted_or_owned_source_cart()
+    {
+        $user = User::factory()->create();
+        $product = Product::factory()->withPrices()->create(['manage_stock' => false]);
+
+        // A cart already owned by (another) customer must not be drained.
+        $owned = Cart::factory()->create([
+            'session_id' => 'socket-A',
+            'customer_id' => $user->id,
+            'customer_type' => get_class($user),
+        ]);
+        $owned->addToCart($product, 1);
+
+        $userCart = CartFacade::mergeGuestIntoUser($owned, $user);
+
+        // Items stayed on the owned cart; nothing moved.
+        $this->assertSame(1, $owned->fresh()->items()->count());
+        $this->assertInstanceOf(Cart::class, $userCart);
+    }
+
+    #[Test]
+    public function checkout_session_link_delegates_to_the_cart_model()
+    {
+        config()->set('shop.stripe.enabled', false);
+
+        $product = Product::factory()->withPrices()->create(['manage_stock' => false]);
+        $guest = Cart::factory()->create(['session_id' => 'socket-A', 'customer_id' => null]);
+        $guest->addToCart($product, 1);
+
+        // The facade passthrough reaches Cart::checkoutSessionLink(), which hits
+        // the Stripe gate — proving delegation is wired (a no-op wrapper would
+        // never surface this error).
+        $this->expectExceptionMessage('Stripe is not enabled');
+        CartFacade::checkoutSessionLink($guest);
+    }
+}