優化門市叫貨流程：實作庫存預扣機制、鎖定自動產生的調撥單明細、修復自動販賣機貨道數量連動 Bug 及狀態同步問題

app/Modules/Inventory/Models/Inventory.php

@@ -17,6 +17,7 @@ class Inventory extends Model
         'warehouse_id',
         'product_id',
         'quantity',
+        'reserved_quantity',
         'location',
         'unit_cost',
         'total_value',
@@ -34,6 +35,8 @@ class Inventory extends Model
     protected $casts = [
         'arrival_date' => 'date:Y-m-d',
         'expiry_date' => 'date:Y-m-d',
+        'quantity' => 'decimal:4',
+        'reserved_quantity' => 'decimal:4',
         'unit_cost' => 'decimal:4',
         'total_value' => 'decimal:4',
     ];
@@ -109,7 +112,33 @@ class Inventory extends Model
         });
     }
 
+    /**
+     * 可用庫存（實體庫存 - 預留庫存）
+     */
+    public function getAvailableQuantityAttribute()
+    {
+        return max(0, $this->quantity - $this->reserved_quantity);
+    }
 
+    /**
+     * 增加預留庫存（鎖定）
+     */
+    public function reserveQuantity(float|int $amount)
+    {
+        if ($amount <= 0) return;
+        $this->reserved_quantity += $amount;
+        $this->save();
+    }
+
+    /**
+     * 釋放預留庫存（解鎖）
+     */
+    public function releaseReservedQuantity(float|int $amount)
+    {
+        if ($amount <= 0) return;
+        $this->reserved_quantity = max(0, $this->reserved_quantity - $amount);
+        $this->save();
+    }
 
     /**
      * 產生批號