收紧媒体导出载荷边界

将图片和音频导出载荷预校验提升到共享 HostBridge 契约
让 H5 facade 按共享媒体导出边界归一化文件名、MIME 和 base64 载荷
保留 Expo 与 Tauri 壳对真实字节和 MIME 的二次校验
增加媒体导出载荷测试和三端壳总门禁反查
同步宿主壳协议文档和共享决策记录

src/services/host-bridge/hostBridge.test.ts

@@ -1053,8 +1053,8 @@ describe('hostBridge', () => {
     ).resolves.toBe(false);
     await expect(
       exportHostImageFile({
-        fileName: '分享卡.png',
-        base64Data: 'c2hhcmUtY2FyZA==',
+        fileName: ' ../分享:卡?.png ',
+        base64Data: ' c2hhcmUtY2FyZA== ',
         mimeType: 'image/png',
       }),
     ).resolves.toBe(true);
@@ -1220,7 +1220,7 @@ describe('hostBridge', () => {
       request: expect.objectContaining({
         method: 'file.exportImage',
         payload: {
-          fileName: '分享卡.png',
+          fileName: '分享-卡-.png',
           base64Data: 'c2hhcmUtY2FyZA==',
           mimeType: 'image/png',
         },
@@ -1536,6 +1536,16 @@ describe('hostBridge', () => {
         timeoutMs: HOST_BRIDGE_USER_INTERACTION_TIMEOUT_MS,
       }),
     });
+
+    invoke.mockClear();
+    await expect(
+      exportHostImageFile({
+        fileName: 'bad.gif',
+        base64Data: 'c2hhcmUtY2FyZA==',
+        mimeType: 'image/gif' as 'image/png',
+      }),
+    ).resolves.toBe(false);
+    expect(invoke).not.toHaveBeenCalled();
   });
 
   test('原生 App 宿主不支持文本导出时回退 H5', async () => {
@@ -1897,6 +1907,16 @@ describe('hostBridge', () => {
         timeoutMs: HOST_BRIDGE_USER_INTERACTION_TIMEOUT_MS,
       }),
     });
+
+    invoke.mockClear();
+    await expect(
+      exportHostAudioFile({
+        fileName: 'empty.wav',
+        base64Data: '   ',
+        mimeType: 'audio/wav',
+      }),
+    ).resolves.toBe(false);
+    expect(invoke).not.toHaveBeenCalled();
   });
 
   test('原生 App 宿主取消导入音频时回退为 false', async () => {

src/services/host-bridge/hostBridge.ts

@@ -43,6 +43,8 @@ import {
   normalizeHostBridgeClipboardText,
   normalizeHostBridgeColorScheme,
   normalizeHostBridgeConnectionType,
+  normalizeHostBridgeExportAudioPayload,
+  normalizeHostBridgeExportImagePayload,
   normalizeHostBridgeExternalUrlPayload,
   normalizeHostBridgeHapticsImpactStyle,
   normalizeHostBridgeLifecycleState,
@@ -854,10 +856,15 @@ export async function exportHostImageFile(
     return false;
   }
 
+  const normalizedPayload = normalizeHostBridgeExportImagePayload(params);
+  if (!normalizedPayload) {
+    return false;
+  }
+
   try {
     return await requestNativeAppHostBridge<FileExportImageResult>(
       'file.exportImage',
-      params,
+      normalizedPayload,
       { timeoutMs: HOST_BRIDGE_USER_INTERACTION_TIMEOUT_MS },
     );
   } catch (error) {
@@ -875,10 +882,15 @@ export async function exportHostAudioFile(
     return false;
   }
 
+  const normalizedPayload = normalizeHostBridgeExportAudioPayload(params);
+  if (!normalizedPayload) {
+    return false;
+  }
+
   try {
     return await requestNativeAppHostBridge<FileExportAudioResult>(
       'file.exportAudio',
-      params,
+      normalizedPayload,
       { timeoutMs: HOST_BRIDGE_USER_INTERACTION_TIMEOUT_MS },
     );
   } catch (error) {