diff --git a/backend/app/services/task_service.py b/backend/app/services/task_service.py
index eaf2535..06d662b 100644
--- a/backend/app/services/task_service.py
+++ b/backend/app/services/task_service.py
@@ -816,6 +816,13 @@ async def transfer_task(
     # 批量 flush 以生成 ID
     await db.flush()
 
+    # 提前查询产品（通知需要 product_sn）
+    product_result = await db.execute(
+        select(Product).where(Product.id == task.product_id)
+    )
+    product = product_result.scalar_one_or_none()
+    product_sn = product.serial_number if product else ""
+
     for nt in created_tasks:
         await _create_task_log(
             db, nt.id,
@@ -826,12 +833,6 @@ async def transfer_task(
         )
         # 🔔 通知：新任务派发
         if nt.assignee_id:
-            product_sn = ""
-            try:
-                if product:
-                    product_sn = product.serial_number or ""
-            except Exception:
-                pass
             db.add(Notification(
                 user_id=nt.assignee_id,
                 title=f"🟢 新任务派发",
@@ -841,10 +842,6 @@ async def transfer_task(
             ))
 
     # --- 更新 Product 的 current_location_id ---
-    product_result = await db.execute(
-        select(Product).where(Product.id == task.product_id)
-    )
-    product = product_result.scalar_one_or_none()
     if product:
         if has_warehouse and not real_branches:
             product.current_location_id = VIRTUAL_WAREHOUSE