fix: avoid duplicate wechat share descriptions

@@ -148,6 +148,27 @@ describe('useShare', () => {
     )
   })
 
+  it('resolver 显式返回空 desc 时不回退为标题或 description', async () => {
+    const router = createRouterMock({
+      meta: { title: '课程详情' },
+    })
+
+    installWxShareSync(router, {
+      isEnabled: true,
+      resolver: vi.fn(() =>
+        Promise.resolve({
+          description: '课程详情',
+          desc: '',
+        })
+      ),
+    })
+
+    await flushMutationObserver()
+
+    expect(wxMocks.updateAppMessageShareData.mock.lastCall[0].title).toBe('美乐爱觉')
+    expect(wxMocks.updateAppMessageShareData.mock.lastCall[0].desc).toBe('')
+  })
+
   it('非 cdn 图片地址保持不变', () => {
     expect(normalizeShareImageUrl('https://example.com/image.png')).toBe(
       'https://example.com/image.png'

@@ -170,15 +170,15 @@ const mergeResolvedShareData = (
     ...(resolvedShareData || {}),
   }
 
-  if (resolvedShareData?.description && !resolvedShareData?.desc) {
+  if (resolvedShareData && 'description' in resolvedShareData && !('desc' in resolvedShareData)) {
     mergedShareData.desc = resolvedShareData.description
   }
 
-  if (resolvedShareData?.image && !resolvedShareData?.imgUrl) {
+  if (resolvedShareData && 'image' in resolvedShareData && !('imgUrl' in resolvedShareData)) {
     mergedShareData.imgUrl = resolvedShareData.image
   }
 
-  if (resolvedShareData?.url && !resolvedShareData?.link) {
+  if (resolvedShareData && 'url' in resolvedShareData && !('link' in resolvedShareData)) {
     mergedShareData.link = resolvedShareData.url
   }
 

@@ -219,15 +219,15 @@ const mergeResolvedOgMeta = (
     ...(resolvedPayload || {}),
   }
 
-  if (resolvedPayload?.desc && !resolvedPayload?.description) {
+  if (resolvedPayload && 'desc' in resolvedPayload && !('description' in resolvedPayload)) {
     mergedPayload.description = resolvedPayload.desc
   }
 
-  if (resolvedPayload?.imgUrl && !resolvedPayload?.image) {
+  if (resolvedPayload && 'imgUrl' in resolvedPayload && !('image' in resolvedPayload)) {
     mergedPayload.image = resolvedPayload.imgUrl
   }
 
-  if (resolvedPayload?.link && !resolvedPayload?.url) {
+  if (resolvedPayload && 'link' in resolvedPayload && !('url' in resolvedPayload)) {
     mergedPayload.url = resolvedPayload.link
   }