diff --git a/app/Domains/Purchase/Services/Checkout/CompleteCheckoutService.php b/app/Domains/Purchase/Services/Checkout/CompleteCheckoutService.php
index 09f7de0..1aae879 100644
--- a/app/Domains/Purchase/Services/Checkout/CompleteCheckoutService.php
+++ b/app/Domains/Purchase/Services/Checkout/CompleteCheckoutService.php
@@ -100,7 +100,7 @@ class CompleteCheckoutService
                 return;
             }
 
-            if ($cart === null || $cart->status !== 'checkout') {
+            if ($cart === null || ! in_array($cart->status, ['active', 'checkout'], true)) {
                 throw ValidationException::withMessages([
                     'items' => __('api.purchase.inconsistent_reservation'),
                 ]);
diff --git a/app/Domains/Purchase/Services/Checkout/ReleaseCheckoutService.php b/app/Domains/Purchase/Services/Checkout/ReleaseCheckoutService.php
index 39f9524..84ab282 100644
--- a/app/Domains/Purchase/Services/Checkout/ReleaseCheckoutService.php
+++ b/app/Domains/Purchase/Services/Checkout/ReleaseCheckoutService.php
@@ -14,22 +14,16 @@ class ReleaseCheckoutService
 {
     public function __construct(
         private readonly StockReservationService $reservations,
-        private readonly SourceCartService $sourceCart,
     ) {}
 
     public function cancel(Purchase $purchase): Purchase
     {
-        return $this->release($purchase, Purchase::STATUS_CANCELLED, restoreCart: true);
-    }
-
-    public function cancelWithoutRestoringCart(Purchase $purchase): Purchase
-    {
-        return $this->release($purchase, Purchase::STATUS_CANCELLED, restoreCart: false);
+        return $this->release($purchase, Purchase::STATUS_CANCELLED);
     }
 
     public function expire(Purchase $purchase): Purchase
     {
-        return $this->release($purchase, Purchase::STATUS_EXPIRED, restoreCart: false);
+        return $this->release($purchase, Purchase::STATUS_EXPIRED);
     }
 
     public function expireOverdue(): int
@@ -66,15 +60,11 @@ class ReleaseCheckoutService
         return $expiredCount;
     }
 
-    private function release(Purchase $purchase, string $targetStatus, bool $restoreCart): Purchase
+    private function release(Purchase $purchase, string $targetStatus): Purchase
     {
-        return DB::transaction(function () use ($purchase, $targetStatus, $restoreCart): Purchase {
+        return DB::transaction(function () use ($purchase, $targetStatus): Purchase {
             $purchase = $this->lockPurchase($purchase);
 
-            if ($targetStatus !== Purchase::STATUS_EXPIRED && ! $restoreCart) {
-                $this->purchaseState->assertNotExpired($purchase);
-            }
-
             if ($purchase->status === Purchase::STATUS_PAID) {
                 if ($targetStatus === Purchase::STATUS_EXPIRED) {
                     return $this->loadPurchase($purchase);
@@ -85,7 +75,7 @@ class ReleaseCheckoutService
                 ]);
             }
 
-            if ($this->isAlreadyReleased($purchase) && ! ($restoreCart && $purchase->status === Purchase::STATUS_EXPIRED)) {
+            if ($this->isAlreadyReleased($purchase)) {
                 return $this->loadPurchase($purchase);
             }
 
@@ -96,8 +86,7 @@ class ReleaseCheckoutService
                 return $this->loadPurchase($purchase);
             }
 
-            $reservationReturnedToCart = $restoreCart && $this->sourceCart->restore($purchase);
-            $this->releaseCartReservations($purchase, $reservationReturnedToCart, $targetStatus);
+            $this->releasePurchaseReservations($purchase, $targetStatus);
 
             $purchase->update(['status' => $targetStatus]);
 
@@ -105,19 +94,20 @@ class ReleaseCheckoutService
         });
     }
 
-    private function releaseCartReservations(
-        Purchase $purchase,
-        bool $reservationReturnedToCart,
-        string $targetStatus,
-    ): void {
-        if ($reservationReturnedToCart) {
+    private function releasePurchaseReservations(Purchase $purchase, string $targetStatus): void
+    {
+        $cart = $purchase->cart()->withTrashed()->lockForUpdate()->first();
+        if ($cart === null) {
+            return;
+        }
+
+        if ($cart->status === 'active') {
             $this->reservations->detachFromPurchase($purchase);
 
             return;
         }
 
-        $cart = $purchase->cart()->withTrashed()->lockForUpdate()->first();
-        if ($cart === null) {
+        if ($cart->status !== 'checkout') {
             return;
         }
 
diff --git a/app/Domains/Purchase/Services/Checkout/SourceCartService.php b/app/Domains/Purchase/Services/Checkout/SourceCartService.php
index 6c75efd..b29a2f3 100644
--- a/app/Domains/Purchase/Services/Checkout/SourceCartService.php
+++ b/app/Domains/Purchase/Services/Checkout/SourceCartService.php
@@ -3,86 +3,10 @@
 namespace App\Domains\Purchase\Services\Checkout;
 
 use App\Domains\Cart\Models\Cart;
-use App\Domains\Cart\Models\CartItem;
-use App\Domains\Catalog\Services\StockReservationService;
 use App\Domains\Purchase\Models\Purchase;
 
 class SourceCartService
 {
-    public function __construct(
-        private readonly StockReservationService $reservations,
-    ) {}
-
-    public function restore(Purchase $purchase): bool
-    {
-        $sourceCart = $this->findSourceCart($purchase);
-
-        if ($sourceCart === null) {
-            return false;
-        }
-
-        if ($sourceCart->origin === Cart::ORIGIN_DIRECT_CHECKOUT) {
-            return false;
-        }
-
-        $this->restoreReservations($sourceCart);
-
-        /** @var Cart|null $activeCart */
-        $activeCart = Cart::query()
-            ->where('tenant_codigo', $purchase->tenant_codigo)
-            ->where('user_id', $purchase->user_id)
-            ->where('status', 'active')
-            ->where('id', '!=', $sourceCart->getKey())
-            ->lockForUpdate()
-            ->first();
-
-        if ($activeCart !== null) {
-            $this->mergeIntoActiveCart($sourceCart, $activeCart);
-
-            $sourceCart->update([
-                'status' => 'converted',
-                'guest_token' => null,
-            ]);
-
-            if (! $sourceCart->trashed()) {
-                $sourceCart->delete();
-            }
-
-            return true;
-        }
-
-        if ($sourceCart->trashed()) {
-            $sourceCart->restore();
-        }
-
-        $sourceCart->update([
-            'status' => 'active',
-            'user_id' => $purchase->user_id,
-            'guest_token' => null,
-        ]);
-
-        return true;
-    }
-
-    private function restoreReservations(Cart $cart): void
-    {
-        $items = $cart->items()->orderBy('id')->lockForUpdate()->get();
-        $items->load([
-            'catalogItem.inventory',
-            'catalogItem.bundleComponents.catalogItem.inventory',
-            'catalogItem.bundleComponents.variant.inventory',
-            'variant.inventory',
-            'variant.catalogItem',
-        ]);
-
-        foreach ($items as $item) {
-            $selection = $item->selectedItem();
-            if ($selection !== null) {
-                $this->reservations->restore($item, $selection);
-            }
-        }
-    }
-
     public function finalize(Purchase $purchase): void
     {
         $sourceCart = $this->findSourceCart($purchase);
@@ -110,30 +34,4 @@ class SourceCartService
             ->lockForUpdate()
             ->first();
     }
-
-    private function mergeIntoActiveCart(Cart $sourceCart, Cart $activeCart): void
-    {
-        $sourceItems = $sourceCart->items()->lockForUpdate()->get();
-
-        foreach ($sourceItems as $sourceItem) {
-            /** @var CartItem|null $activeItem */
-            $activeItem = $activeCart->items()
-                ->where('catalog_item_id', $sourceItem->catalog_item_id)
-                ->where('variant_id', $sourceItem->variant_id)
-                ->lockForUpdate()
-                ->first();
-
-            if ($activeItem === null) {
-                $activeItem = $activeCart->items()->create([
-                    'catalog_item_id' => $sourceItem->catalog_item_id,
-                    'variant_id' => $sourceItem->variant_id,
-                    'cantidad' => $sourceItem->cantidad,
-                ]);
-            } else {
-                $activeItem->increment('cantidad', (int) $sourceItem->cantidad);
-            }
-
-            $this->reservations->transfer($sourceItem, $activeItem);
-        }
-    }
 }
diff --git a/app/Domains/Purchase/Services/Checkout/StartCheckoutService.php b/app/Domains/Purchase/Services/Checkout/StartCheckoutService.php
index c2f723d..3e20932 100644
--- a/app/Domains/Purchase/Services/Checkout/StartCheckoutService.php
+++ b/app/Domains/Purchase/Services/Checkout/StartCheckoutService.php
@@ -274,13 +274,6 @@ class StartCheckoutService
             );
         }
 
-        // The purchase owns the reservation until checkout finishes. The cart is
-        // retained so it can be restored if the purchase is cancelled or expires.
-        $cart->update([
-            'status' => 'checkout',
-            'guest_token' => null,
-        ]);
-
         return $this->loadPurchase($purchase);
     }
 
@@ -299,6 +292,14 @@ class StartCheckoutService
             ]);
         }
 
+        if ($cart->purchases()
+            ->whereIn('status', [Purchase::STATUS_CREATED, Purchase::STATUS_PENDING_PAYMENT])
+            ->exists()) {
+            throw ValidationException::withMessages([
+                'cart_id' => __('api.purchase.checkout_in_progress'),
+            ]);
+        }
+
         return $cart;
     }
 
diff --git a/app/Domains/Purchase/Services/CheckoutService.php b/app/Domains/Purchase/Services/CheckoutService.php
index 411f1b2..90ad1bc 100644
--- a/app/Domains/Purchase/Services/CheckoutService.php
+++ b/app/Domains/Purchase/Services/CheckoutService.php
@@ -68,11 +68,6 @@ class CheckoutService
         return $this->releaser->cancel($purchase);
     }
 
-    public function cancelPurchaseWithoutRestoringCart(Purchase $purchase): Purchase
-    {
-        return $this->releaser->cancelWithoutRestoringCart($purchase);
-    }
-
     public function expirePurchase(Purchase $purchase): Purchase
     {
         return $this->releaser->expire($purchase);
diff --git a/app/Domains/Purchase/Services/UserPurchaseLimitService.php b/app/Domains/Purchase/Services/UserPurchaseLimitService.php
index 6baa6fb..1e2b5ec 100644
--- a/app/Domains/Purchase/Services/UserPurchaseLimitService.php
+++ b/app/Domains/Purchase/Services/UserPurchaseLimitService.php
@@ -86,7 +86,9 @@ class UserPurchaseLimitService
                         $excludedCartId !== null,
                         fn ($query) => $query->whereKeyNot($excludedCartId),
                     ))
-                ->whereHas('stockReservations', fn ($query) => $query->where('status', 'active'))
+                ->whereHas('stockReservations', fn ($query) => $query
+                    ->where('status', 'active')
+                    ->whereNull('purchase_id'))
                 ->sum('cantidad');
 
             if ($purchasedQuantity + $checkoutQuantity + $reservedCartQuantity + $requestedQuantity > $limit) {
@@ -152,7 +154,9 @@ class UserPurchaseLimitService
             ->whereHas('cart', fn ($query) => $query
                 ->where('user_id', $userId)
                 ->where('status', 'active'))
-            ->whereHas('stockReservations', fn ($query) => $query->where('status', 'active'))
+            ->whereHas('stockReservations', fn ($query) => $query
+                ->where('status', 'active')
+                ->whereNull('purchase_id'))
             ->groupBy('catalog_item_id')
             ->pluck('quantity', 'catalog_item_id');
 
diff --git a/app/Domains/Sale/Services/AdminAppSaleService.php b/app/Domains/Sale/Services/AdminAppSaleService.php
index 75ae593..5a008d3 100644
--- a/app/Domains/Sale/Services/AdminAppSaleService.php
+++ b/app/Domains/Sale/Services/AdminAppSaleService.php
@@ -79,7 +79,7 @@ class AdminAppSaleService
         $sale = $this->findForTenant($tenant, $saleId);
 
         return $this->saleForResponse(
-            $this->checkoutService->cancelPurchaseWithoutRestoringCart($sale)
+            $this->checkoutService->cancelPurchase($sale)
         );
     }
 
diff --git a/lang/en/api.php b/lang/en/api.php
index f0356ed..e4780e6 100644
--- a/lang/en/api.php
+++ b/lang/en/api.php
@@ -55,6 +55,7 @@ return [
         'catalog_item_missing' => 'One or more catalog items could not be loaded.',
         'catalog_item_wrong_tenant' => 'One or more catalog items do not belong to the tenant.',
         'inactive_cart' => 'The selected cart is no longer active.',
+        'checkout_in_progress' => 'The cart already has a purchase in progress.',
         'not_available_for_payment' => 'The purchase is no longer available for payment.',
         'not_available_for_review' => 'The purchase is no longer available for review.',
     ],
diff --git a/lang/es/api.php b/lang/es/api.php
index bfa17c4..bbf2cd9 100644
--- a/lang/es/api.php
+++ b/lang/es/api.php
@@ -55,6 +55,7 @@ return [
         'catalog_item_missing' => 'No se pudieron cargar uno o más productos del catálogo.',
         'catalog_item_wrong_tenant' => 'Uno o más productos no pertenecen al tenant.',
         'inactive_cart' => 'El carrito seleccionado ya no está activo.',
+        'checkout_in_progress' => 'El carrito ya tiene una compra en curso.',
         'not_available_for_payment' => 'La compra ya no está disponible para el pago.',
         'not_available_for_review' => "La compra ya no est\u{00E1} disponible para revisi\u{00F3}n.",
     ],
diff --git a/tests/Feature/Purchase/StorePurchaseTest.php b/tests/Feature/Purchase/StorePurchaseTest.php
index 12901e4..5048121 100644
--- a/tests/Feature/Purchase/StorePurchaseTest.php
+++ b/tests/Feature/Purchase/StorePurchaseTest.php
@@ -126,7 +126,8 @@ class StorePurchaseTest extends TestCase
         $this->assertDatabaseHas('carritos', [
             'id' => $cartId,
             'user_id' => $user->id,
-            'status' => 'checkout',
+            'status' => 'active',
+            'origin' => Cart::ORIGIN_USER,
             'deleted_at' => null,
         ]);
         $this->assertDatabaseHas('carrito_items', [
@@ -141,6 +142,21 @@ class StorePurchaseTest extends TestCase
             'reserved_stock' => 2,
         ]);
 
+        $this->actingAs($user, 'sanctum')
+            ->getJson('/api/tenants/sonder/cart')
+            ->assertOk()
+            ->assertJsonPath('data.id', $cartId)
+            ->assertJsonPath('data.status', 'active')
+            ->assertJsonCount(1, 'data.items')
+            ->assertJsonPath('data.items.0.cantidad', 2);
+
+        $this->actingAs($user, 'sanctum')
+            ->postJson('/api/tenants/sonder/compras/start-checkout', [
+                'cart_id' => $cartId,
+            ])
+            ->assertUnprocessable()
+            ->assertJsonValidationErrors('cart_id');
+
         $catalogItem->update([
             'nombre' => 'Updated Product',
             'precio' => '75.00',
@@ -423,18 +439,26 @@ class StorePurchaseTest extends TestCase
         ]);
     }
 
-    public function test_it_restores_the_source_cart_when_checkout_is_cancelled(): void
+    public function test_it_keeps_the_source_cart_active_and_only_cancels_the_purchase(): void
     {
         $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
         $user = User::factory()->create();
         $variant = $this->createVariantForTenant('sonder', 10, '50.00');
         $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 3);
+        $activeCart = Cart::query()
+            ->where('user_id', $user->id)
+            ->where('status', 'active')
+            ->firstOrFail();
+        $cartItemId = $purchase->cart->items()->firstOrFail()->id;
 
         $this->assertDatabaseHas('carritos', [
             'id' => $purchase->cart_id,
-            'status' => 'checkout',
+            'status' => 'active',
+            'origin' => Cart::ORIGIN_USER,
             'deleted_at' => null,
         ]);
+        $this->assertDatabaseCount('carrito_items', 1);
+        $this->assertSame(1, $activeCart->items()->count());
 
         $this->actingAs($user, 'sanctum')
             ->postJson("/api/tenants/sonder/compras/{$purchase->id}/cancel")
@@ -442,29 +466,35 @@ class StorePurchaseTest extends TestCase
             ->assertJsonPath('data.status', Purchase::STATUS_CANCELLED);
 
         $this->assertDatabaseHas('carritos', [
-            'id' => $purchase->cart_id,
+            'id' => $activeCart->id,
             'user_id' => $user->id,
             'status' => 'active',
             'deleted_at' => null,
         ]);
-        $this->assertDatabaseHas('carrito_items', [
-            'cart_id' => $purchase->cart_id,
-            'catalog_item_id' => $variant->catalog_item_id,
-            'variant_id' => $variant->id,
-            'cantidad' => 3,
-        ]);
         $this->assertDatabaseHas('inventories', [
             'id' => $variant->inventory_id,
             'reserved_stock' => 3,
         ]);
+        $this->assertDatabaseHas('stock_reservations', [
+            'cart_item_id' => $cartItemId,
+            'purchase_id' => null,
+            'quantity' => 3,
+            'status' => 'active',
+        ]);
+        $this->assertSame(1, $activeCart->items()->count());
     }
 
-    public function test_it_restores_and_reserves_the_source_cart_when_an_expired_checkout_is_modified(): void
+    public function test_it_expires_the_purchase_without_mutating_the_active_cart(): void
     {
         $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
         $user = User::factory()->create();
         $variant = $this->createVariantForTenant('sonder', 10, '50.00');
         $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 3);
+        $activeCart = Cart::query()
+            ->where('user_id', $user->id)
+            ->where('status', 'active')
+            ->firstOrFail();
+        $cartItemId = $purchase->cart->items()->firstOrFail()->id;
         $purchase->update(['expires_at' => now()->subMinute()]);
 
         $this->artisan('reservations:expire')->assertSuccessful();
@@ -475,64 +505,21 @@ class StorePurchaseTest extends TestCase
         ]);
         $this->assertDatabaseHas('inventories', [
             'id' => $variant->inventory_id,
-            'reserved_stock' => 0,
+            'reserved_stock' => 3,
         ]);
-
-        $this->actingAs($user, 'sanctum')
-            ->postJson("/api/tenants/sonder/compras/{$purchase->id}/cancel")
-            ->assertOk()
-            ->assertJsonPath('data.status', Purchase::STATUS_CANCELLED);
-
         $this->assertDatabaseHas('carritos', [
-            'id' => $purchase->cart_id,
+            'id' => $activeCart->id,
             'user_id' => $user->id,
             'status' => 'active',
             'deleted_at' => null,
         ]);
-        $this->assertDatabaseHas('inventories', [
-            'id' => $variant->inventory_id,
-            'reserved_stock' => 3,
-        ]);
-    }
-
-    public function test_it_merges_the_checkout_cart_when_the_user_created_another_active_cart(): void
-    {
-        $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
-        $user = User::factory()->create();
-        $variant = $this->createVariantForTenant('sonder', 10, '50.00');
-        $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 2);
-
-        $activeCartId = $this->actingAs($user, 'sanctum')
-            ->postJson('/api/tenants/sonder/cart/items', [
-                'catalog_item_id' => $variant->catalog_item_id,
-                'variant_id' => $variant->id,
-                'cantidad' => 1,
-            ])
-            ->assertOk()
-            ->json('data.id');
-
-        $this->assertNotSame($purchase->cart_id, $activeCartId);
-
-        $this->actingAs($user, 'sanctum')
-            ->postJson("/api/tenants/sonder/compras/{$purchase->id}/cancel")
-            ->assertOk();
-
-        $this->assertDatabaseHas('carritos', [
-            'id' => $activeCartId,
-            'user_id' => $user->id,
+        $this->assertDatabaseHas('stock_reservations', [
+            'cart_item_id' => $cartItemId,
+            'purchase_id' => null,
+            'quantity' => 3,
             'status' => 'active',
-            'deleted_at' => null,
-        ]);
-        $this->assertDatabaseHas('carrito_items', [
-            'cart_id' => $activeCartId,
-            'catalog_item_id' => $variant->catalog_item_id,
-            'variant_id' => $variant->id,
-            'cantidad' => 3,
-        ]);
-        $this->assertDatabaseHas('inventories', [
-            'id' => $variant->inventory_id,
-            'reserved_stock' => 3,
         ]);
+        $this->assertSame(1, $activeCart->items()->count());
     }
 
     public function test_it_keeps_cart_items_during_checkout_and_updates_customer_data(): void
@@ -783,12 +770,16 @@ class StorePurchaseTest extends TestCase
         ]);
     }
 
-    public function test_it_expires_an_abandoned_purchase_and_releases_its_checkout_cart(): void
+    public function test_it_expires_an_abandoned_purchase_without_mutating_its_active_cart(): void
     {
         $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
         $user = User::factory()->create();
         $variant = $this->createVariantForTenant('sonder', 10, '50.00');
         $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 3);
+        $activeCart = Cart::query()
+            ->where('user_id', $user->id)
+            ->where('status', 'active')
+            ->firstOrFail();
 
         $this->assertNotNull($purchase->expires_at);
         $this->assertDatabaseHas('inventories', [
@@ -812,21 +803,23 @@ class StorePurchaseTest extends TestCase
             'cantidad' => 3,
         ]);
         $this->assertDatabaseHas('stock_reservations', [
-            'purchase_id' => $purchase->id,
-            'quantity' => 0,
-            'status' => 'expired',
+            'purchase_id' => null,
+            'quantity' => 3,
+            'status' => 'active',
         ]);
         $this->assertDatabaseHas('inventories', [
             'id' => $variant->inventory_id,
             'real_stock' => 10,
-            'reserved_stock' => 0,
+            'reserved_stock' => 3,
             'sold_units' => 0,
         ]);
-        $this->assertSoftDeleted('carritos', [
-            'id' => $purchase->cart_id,
+        $this->assertDatabaseHas('carritos', [
+            'id' => $activeCart->id,
             'user_id' => $user->id,
-            'status' => 'converted',
+            'status' => 'active',
+            'deleted_at' => null,
         ]);
+        $this->assertSame(1, $activeCart->items()->count());
 
         $this->artisan('reservations:expire')
             ->expectsOutput('Expired purchases: 0')
@@ -838,9 +831,10 @@ class StorePurchaseTest extends TestCase
     {
         $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
         $user = User::factory()->create();
+        $secondUser = User::factory()->create();
         $variant = $this->createVariantForTenant('sonder', 10, '50.00');
         $inconsistentPurchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 1);
-        $validPurchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 1);
+        $validPurchase = $this->createCheckoutPurchase($secondUser, 'sonder', $variant, 1);
 
         $inconsistentPurchase->items()->create([
             'source_catalog_item_id' => $variant->catalog_item_id,
@@ -956,12 +950,10 @@ class StorePurchaseTest extends TestCase
     public function test_created_and_pending_payment_purchase_details_ignore_later_cart_changes(): void
     {
         $this->createTenant('sonder', 'Sonder', 'sonder.com.ar');
-        $user = User::factory()->create([
-            'email' => 'buyer@example.com',
-        ]);
         $variant = $this->createVariantForTenant('sonder', 10, '50.00');
 
         foreach ([Purchase::STATUS_CREATED, Purchase::STATUS_PENDING_PAYMENT] as $status) {
+            $user = User::factory()->create();
             $purchase = $this->createCheckoutPurchase($user, 'sonder', $variant, 2);
             $purchase->cart->items()->update(['cantidad' => 3]);
             $purchase->update(['status' => $status]);