diff --git a/track-uniapp/src/pages/scan/components/TreeCanvas.vue b/track-uniapp/src/pages/scan/components/TreeCanvas.vue
index e83b9bd..caedfd5 100644
--- a/track-uniapp/src/pages/scan/components/TreeCanvas.vue
+++ b/track-uniapp/src/pages/scan/components/TreeCanvas.vue
@@ -66,12 +66,10 @@ export default {
       const layout = (tasks, parentRowIdx, parentX) => {
         if (!tasks || !tasks.length) return;
         tasks.forEach(t => {
-          // 时间戳判定：子任务创建于父任务完成之后 → 串行(下一行)；否则 → 并行(同Y偏右)
-          const parentNode = this.taskDataMap[t.parent_task_id];
-          const isSerial = !t.parent_task_id || (
-            parentNode && parentNode.completed_at &&
-            new Date(t.created_at) > new Date(parentNode.completed_at)
-          );
+          // 工业拓扑：父WIP→并行(同Y)；父COMPLETED→串行(换行)
+          // 后端保证 COMPLETED 后不可 spawn，故 COMPLETED 的子任务必为转交产物
+          const parent = this.taskDataMap[t.parent_task_id];
+          const isSerial = !t.parent_task_id || (parent && parent.status === 'COMPLETED');
           const rowIdx = isSerial ? (parentRowIdx >= 0 ? parentRowIdx + 1 : rows.length) : parentRowIdx;
           while (rows.length <= rowIdx) rows.push({ y: 0, tasks: [] });