diff --git a/apps/ai-game-creator-shell/tests/gameDistributionPublish.test.ts b/apps/ai-game-creator-shell/tests/gameDistributionPublish.test.ts
index ca3a01b6c..9b2e3ed78 100644
--- a/apps/ai-game-creator-shell/tests/gameDistributionPublish.test.ts
+++ b/apps/ai-game-creator-shell/tests/gameDistributionPublish.test.ts
@@ -45,28 +45,7 @@ function installNativeInvoke(
 }
 
 beforeEach(() => {
-  // Node 26 + jsdom 下 `window.localStorage` 可能没被注入（getter 返回 undefined）。
-  // 测试只需要「清空」这一动作，缺失时补一个内存实现，别让环境差异把整文件打红。
-  if (!window.localStorage) {
-    const store = new Map<string, string>();
-    Object.defineProperty(window, 'localStorage', {
-      configurable: true,
-      value: {
-        get length() {
-          return store.size;
-        },
-        clear: () => store.clear(),
-        getItem: (key: string) => store.get(key) ?? null,
-        key: (index: number) => Array.from(store.keys())[index] ?? null,
-        removeItem: (key: string) => {
-          store.delete(key);
-        },
-        setItem: (key: string, value: string) => {
-          store.set(key, String(value));
-        },
-      },
-    });
-  }
+  // `window.localStorage` 由 vitest setupFiles（`tests/jsdomLocalStorageSetup.ts`）兜底。
   window.localStorage.clear();
 });
 
diff --git a/apps/ai-game-creator-shell/tests/jsdomLocalStorageSetup.ts b/apps/ai-game-creator-shell/tests/jsdomLocalStorageSetup.ts
new file mode 100644
index 000000000..72e01a11b
--- /dev/null
+++ b/apps/ai-game-creator-shell/tests/jsdomLocalStorageSetup.ts
@@ -0,0 +1,37 @@
+// Node 26 + jsdom 组合下 `window.localStorage` 可能未被注入（getter 返回 undefined）。
+// 仓库里的 jsdom 用例只依赖内存语义（clear/getItem/setItem/removeItem/length/key），
+// 缺失时补一个同形实现，避免环境差异把整份用例打红。
+//
+// 这是 vitest `setupFiles` 的副作用文件，不是测试文件：它必须在每个 jsdom 用例文件
+// 自己的顶层代码之前跑完，所以不能靠某个用例文件里的 `beforeEach` 来兜底。
+
+function installInMemoryLocalStorage(): void {
+  if (typeof window === 'undefined') return;
+  let existing: unknown;
+  try {
+    existing = window.localStorage;
+  } catch {
+    existing = undefined;
+  }
+  if (existing) return;
+  const store = new Map<string, string>();
+  Object.defineProperty(window, 'localStorage', {
+    configurable: true,
+    value: {
+      get length() {
+        return store.size;
+      },
+      clear: () => store.clear(),
+      getItem: (key: string) => store.get(key) ?? null,
+      key: (index: number) => Array.from(store.keys())[index] ?? null,
+      removeItem: (key: string) => {
+        store.delete(key);
+      },
+      setItem: (key: string, value: string) => {
+        store.set(key, String(value));
+      },
+    },
+  });
+}
+
+installInMemoryLocalStorage();
diff --git a/vitest.config.ts b/vitest.config.ts
index d5187097f..93386e122 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -94,6 +94,10 @@ export default defineConfig({
   test: {
     environment: 'node',
     globals: true,
+    // Node 26 + jsdom 下 `window.localStorage` 可能未注入；这里在每个用例文件前补内存实现。
+    setupFiles: [
+      './apps/ai-game-creator-shell/tests/jsdomLocalStorageSetup.ts',
+    ],
     // 成功用例不回放被测代码写进 stdout / stderr 的内容：CI 日志里只保留每个
     // 失败用例的断言摘要，避免 React act 警告、dev 调度日志这类噪音刷屏。
     // 需要在本机排查时用 `vitest run --silent=false` 覆盖本次配置。