diff --git a/apps/mobile-shell/scripts/check-config.mjs b/apps/mobile-shell/scripts/check-config.mjs
index 7b17c9cdd..22798d81d 100644
--- a/apps/mobile-shell/scripts/check-config.mjs
+++ b/apps/mobile-shell/scripts/check-config.mjs
@@ -42,6 +42,11 @@ const capabilitiesTestPath = new URL(
 const capabilitiesTestSource = fs.readFileSync(capabilitiesTestPath, 'utf8');
 const clipboardPath = new URL('../src/host-bridge/clipboard.ts', import.meta.url);
 const clipboardSource = fs.readFileSync(clipboardPath, 'utf8');
+const clipboardTestPath = new URL(
+  '../src/host-bridge/clipboard.test.ts',
+  import.meta.url,
+);
+const clipboardTestSource = fs.readFileSync(clipboardTestPath, 'utf8');
 const dispatchPath = new URL('../src/host-bridge/dispatch.ts', import.meta.url);
 const dispatchSource = fs.readFileSync(dispatchPath, 'utf8');
 const dispatchTestPath = new URL(
@@ -2156,9 +2161,19 @@ for (const snippet of [
     throw new Error(`mobile shell clipboard module is missing ${snippet}`);
   }
 }
-if (!bridgeTestSource.includes("'猫'.repeat(100000)")) {
+if (!clipboardTestSource.includes("'猫'.repeat(100000)")) {
   throw new Error('mobile shell clipboard tests must cover Unicode truncation');
 }
+for (const snippet of [
+  'rejects unavailable clipboard text without reporting a successful empty value',
+  'Clipboard.getStringAsync).mockResolvedValue(undefined as never)',
+  "code: 'host_error'",
+  "message: 'clipboard text unavailable'",
+]) {
+  if (!clipboardTestSource.includes(snippet)) {
+    throw new Error(`mobile shell clipboard tests must cover unavailable reads: ${snippet}`);
+  }
+}
 
 if (
   !hapticsSource.includes('normalizeHostBridgeHapticsImpactStyle(rawStyle)') ||
diff --git a/apps/mobile-shell/src/host-bridge/clipboard.test.ts b/apps/mobile-shell/src/host-bridge/clipboard.test.ts
index d7f08ad5a..1f1d49da4 100644
--- a/apps/mobile-shell/src/host-bridge/clipboard.test.ts
+++ b/apps/mobile-shell/src/host-bridge/clipboard.test.ts
@@ -119,6 +119,15 @@ describe('mobile clipboard helpers', () => {
     });
   });
 
+  test('rejects unavailable clipboard text without reporting a successful empty value', async () => {
+    vi.mocked(Clipboard.getStringAsync).mockResolvedValue(undefined as never);
+
+    await expect(readMobileClipboardText()).rejects.toMatchObject({
+      code: 'host_error',
+      message: 'clipboard text unavailable',
+    });
+  });
+
   test('wraps HostBridge clipboard read responses', async () => {
     vi.mocked(Clipboard.getStringAsync).mockResolvedValue('作品号 PZ-1');
 
diff --git a/docs/project-memory/shared-memory/decision-log.md b/docs/project-memory/shared-memory/decision-log.md
index c65e6c9e9..cd5d2ca56 100644
--- a/docs/project-memory/shared-memory/decision-log.md
+++ b/docs/project-memory/shared-memory/decision-log.md
@@ -114,7 +114,7 @@
 - 2026-06-19 草稿生成 HostBridge 消费门禁：`PlatformEntryFlowShellImpl` 只负责派生草稿通知和未读数量，实际宿主同步经 `platformHostBridgeSync.ts` 调用 `showHostLocalNotification` / `setHostAppBadgeCount`；`npm run check:native-shells` 必须运行该同步层的真实 Tauri transport 测试，并继续覆盖通知模型、未读计数模型、音频导入和文档导入等 H5 HostBridge 消费测试。
 - 2026-06-18 剪贴板读取能力：新增 `clipboard.readText` HostBridge capability，H5 只能读取纯文本结果，契约限制返回文本最多 100000 字符；Expo 壳通过 `expo-clipboard` 读取系统剪贴板文本，Tauri 壳通过 Rust 侧 `tauri-plugin-clipboard-manager` 读取文本且不开放插件 JS guest API。该能力不读取图片、HTML、文件列表或剪贴板监听事件，宿主未声明或读取失败时由 H5 视作失败并保留原流程。
 - 2026-06-19 移动壳剪贴板边界：Expo `clipboard.writeText` / `clipboard.readText` 的系统剪贴板读写、共享 100000 字符归一、payload 校验和 HostBridge 成功 / 失败响应边界统一收口在 `apps/mobile-shell/src/host-bridge/clipboard.ts`；`dispatch.ts` 只负责把 HostBridge request 委托给 `writeMobileHostBridgeClipboardText(request)` / `readMobileHostBridgeClipboardText(request)`，不得直接导入 `expo-clipboard`、调用 `Clipboard.setStringAsync` / `Clipboard.getStringAsync` 或包装剪贴板成功响应。移动壳配置检查会覆盖该模块结构、共享文本边界和 dispatch 委托关系，避免剪贴板能力散落到分发层。
-- 2026-06-20 移动剪贴板单测边界：`apps/mobile-shell/src/host-bridge/clipboard.test.ts` 直接覆盖 Expo `clipboard.writeText` / `clipboard.readText` 的共享文本归一、100000 字符截断、非字符串写入拒绝、空字符串纯文本读写、系统剪贴板读写调用和 HostBridge 成功 / 失败响应包装；根级 `npm run check:native-shells` 会把该测试文件列入移动桥接层结构清单，避免移动剪贴板边界只靠完整 HostBridge bridge 流程间接覆盖。
+- 2026-06-20 移动剪贴板单测边界：`apps/mobile-shell/src/host-bridge/clipboard.test.ts` 直接覆盖 Expo `clipboard.writeText` / `clipboard.readText` 的共享文本归一、100000 字符截断、非字符串写入拒绝、空字符串纯文本读写、不可用读取返回 `host_error`、系统剪贴板读写调用和 HostBridge 成功 / 失败响应包装；根级 `npm run check:native-shells` 会把该测试文件列入移动桥接层结构清单，移动壳配置检查会反查不可用读取失败语义，避免移动剪贴板边界只靠完整 HostBridge bridge 流程间接覆盖或把底层不可用值伪装成成功空文本。
 - 2026-06-19 桌面壳剪贴板边界：Tauri `clipboard.writeText` / `clipboard.readText` 的系统剪贴板读写、共享 100000 字符归一、payload 校验和响应边界统一收口在 `apps/desktop-shell/src-tauri/src/host_bridge/clipboard.rs`；`dispatch.rs` 只负责把 HostBridge request 委托给 `write_desktop_host_bridge_clipboard_text(...)` / `read_desktop_host_bridge_clipboard_text(...)`，不得直接承接剪贴板文本截断、payload 解析或插件读写细节；桌面 share fallback 仍可调用底层写剪贴板函数复制分享文本。桌面壳配置检查会覆盖该模块结构、共享文本边界和 dispatch 委托关系，避免剪贴板能力散落到分发层。
 - 2026-06-19 桌面壳本地通知边界：Tauri `notification.showLocal` 的 payload 清洗、权限状态检查、prompt 权限请求和系统通知发送统一收口在 `apps/desktop-shell/src-tauri/src/host_bridge/notifications.rs`；`dispatch.rs` 只负责把 HostBridge request 委托给 `show_desktop_local_notification(...)` 并映射响应，不得直接调用 `app.notification()`、`NotificationExt` 或 `PermissionState`。桌面壳配置检查会覆盖该模块结构、权限语义和 dispatch 委托关系，避免本地通知能力散落到分发层。
 - 2026-06-18 文本文件导入能力：新增 `file.importText` HostBridge capability，H5 统一通过 `importHostTextFile()` 读取宿主返回的纯文本内容；Expo 壳通过 `expo-document-picker` 打开系统文档选择器，Tauri 壳通过系统文件选择框读取真实文本文件。两端只接受 `text/plain`、`text/markdown`、`text/csv`、`application/json` 或对应扩展名，单次不超过 5 MiB，成功只返回清洗后的文件名、MIME、UTF-8 文本内容和字节数，不暴露设备 URI / 本机绝对路径，也不开放通用文件系统。Expo 文本导入的 DocumentPicker 调用、大小校验、文本读取和 HostBridge 成功响应包装统一收口在 `apps/mobile-shell/src/host-bridge/files.ts`，`dispatch.ts` 只委托文件模块。