diff --git a/admin-frontend-vue/src/pages/asin/product-category-model.ts b/admin-frontend-vue/src/pages/asin/product-category-model.ts
index 5749607a..dba5635d 100644
--- a/admin-frontend-vue/src/pages/asin/product-category-model.ts
+++ b/admin-frontend-vue/src/pages/asin/product-category-model.ts
@@ -165,7 +165,9 @@ export function makeCategoryLoadMoreNode(
   loadedCount: number,
   totalCount: number,
 ): CategoryLoadMoreNode {
-  const syntheticId = parentId ? -parentId : -1
+  // 合成 id 独立负数域(-2_000_000 以下)：父级 id=1 时 -parentId=-1 会与根级(-1)撞 key，
+  // el-tree node-key 重复会致节点状态错位(子级挂错父级)。placeholder 域(-1_000_000)与此错开。
+  const syntheticId = -(parentId ?? 0) - 2_000_000
   return {
     id: syntheticId,
     parentId,
diff --git a/admin-frontend-vue/tests/align-category-tree.test.ts b/admin-frontend-vue/tests/align-category-tree.test.ts
index 194b0d31..e971acb9 100644
--- a/admin-frontend-vue/tests/align-category-tree.test.ts
+++ b/admin-frontend-vue/tests/align-category-tree.test.ts
@@ -1,7 +1,7 @@
 import test from 'node:test'
 import assert from 'node:assert/strict'
 import { readSource } from './helpers.ts'
-import { isCategoryPlaceholderNode, toProductCategoryNode, makeCategoryPlaceholderNode } from '../src/pages/asin/product-category-model.ts'
+import { isCategoryPlaceholderNode, toProductCategoryNode, makeCategoryPlaceholderNode, makeCategoryLoadMoreNode } from '../src/pages/asin/product-category-model.ts'
 
 // 验收反馈：类目树太紧凑、没有折叠展开、父子级效果对齐旧版（旧版为缩进树形表格带 +/- 展开）。
 // 不变式：childCount>0 的未加载节点带占位子级(children 非空)，el-tree 因此显示展开箭头；
@@ -42,3 +42,19 @@ test('align_category_tree_dependency_failure_returns_actionable_message', () =>
   assert.match(page, /\.node-row\s*\{[^}]*padding/, '节点行有 padding')
   assert.match(page, /el-tree-node__expand-icon|expand-icon/, '展开图标样式定制')
 })
+
+test('align_category_tree_synthetic_ids_are_unique', () => {
+  // 修复回归：合成节点 id 唯一——根级 loadMore 与父级1的 loadMore 不得同 key（曾因 -1 撞 key 致子级挂错父级）。
+  const ids = new Set<number>()
+  const samples = [
+    makeCategoryLoadMoreNode(null, 1, 2).id,
+    makeCategoryLoadMoreNode(1, 1, 2).id,
+    makeCategoryLoadMoreNode(2, 1, 2).id,
+    makeCategoryPlaceholderNode(null).id,
+    makeCategoryPlaceholderNode(1).id,
+    makeCategoryPlaceholderNode(2).id,
+  ]
+  for (const id of samples) ids.add(id)
+  assert.equal(ids.size, samples.length, '合成节点 id 两两唯一')
+  assert.ok(makeCategoryLoadMoreNode(null, 1, 2).id !== -1, '根级 loadMore 不得使用 -1（与父级1的旧式 -parentId 撞 key）')
+})