fix(流转树): 在库设备无在库任务时追加虚拟在库节点

- 设备在库(virtual_warehouse)但无在库任务时，流转树追加虚拟「在库」节点
- 转入人用最后一道主工序负责人兜底(近似)，显示在库归属
- 递归检查任务树避免重复追加(在库任务可能是子任务)

backend/app/services/product_service.py

@@ -154,6 +154,43 @@ async def get_product_by_serial(db: AsyncSession, serial_number: str) -> Product
                 t.created_by = prev[-1].assignee_id
                 assignee_ids.add(t.created_by)
 
+    # 🔧 在库设备若无「在库」任务，追加虚拟「在库」节点（展示谁转入在库）
+    def _has_warehouse_task(tasks):
+        for t in tasks:
+            if t.task_name and ("在库" in t.task_name or "入库" in t.task_name):
+                return True
+            if t.child_tasks and _has_warehouse_task(t.child_tasks):
+                return True
+        return False
+    has_warehouse_task = _has_warehouse_task(task_tree)
+    if product.current_location_id == "virtual_warehouse" and not has_warehouse_task and all_mains:
+        from app.schemas.task import TaskResponse
+        last_main = all_mains[-1]
+        virtual = TaskResponse(
+            id=uuid.uuid4(),
+            product_id=product.id,
+            product_sn=product.serial_number,
+            product_material=product.material_name or product.material_id or "",
+            parent_task_id=None,
+            task_name="在库",
+            assignee_id="virtual_warehouse",
+            status="COMPLETED",
+            notify_parent_on_complete=False,
+            is_rework=False,
+            task_type=None,
+            remark=None,
+            reject_reason=None,
+            received_at=last_main.received_at or last_main.created_at,
+            completed_at=last_main.completed_at,
+            created_at=last_main.created_at,
+            child_tasks=[],
+            records=[],
+            created_by=last_main.assignee_id,  # 最后一道主工序负责人（近似转入人）
+        )
+        task_tree.append(virtual)
+        if virtual.created_by:
+            assignee_ids.add(virtual.created_by)
+
     # 🔧 中文名映射（负责人 + 创建人，供前端显示"谁转入在库"等）
     assignee_names = _lookup_display_names(list(assignee_ids))