fix sync missing articles

vue/src/composables/__tests__/useFeeds.spec.js

@@ -12,7 +12,7 @@ class FakeIntersectionObserver {
 vi.stubGlobal('IntersectionObserver', FakeIntersectionObserver)
 
 describe('useFeeds', () => {
-  const { feeds, showMessage, message, showModal, fetchData, sync, getReadable } = useFeeds()
+  const { feeds, showMessage, message, showModal, fetchData, sync, getReadable, setInitialLoad, handleIntersection } = useFeeds()
 
   beforeEach(() => {
     localStorage.setItem('user-token', 'test-token')
@@ -91,6 +91,31 @@ describe('useFeeds', () => {
     expect(axios.get).toHaveBeenCalledWith('/api/v1/article/get/7', expect.anything())
   })
 
+  it('marks the correct articles read when several scroll out of view in one batch', async () => {
+    feeds.value = [
+      { id: 101, title: 'First' },
+      { id: 102, title: 'Second' },
+      { id: 103, title: 'Third' },
+    ]
+    setInitialLoad(true)
+    axios.put.mockResolvedValue({ status: 200 })
+
+    // Both the first and second articles scrolled above the viewport in the
+    // same IntersectionObserver callback — their `target.id` reflects their
+    // original render-time indices (0 and 1).
+    await handleIntersection([
+      { isIntersecting: false, boundingClientRect: { y: -10 }, target: { id: '0' } },
+      { isIntersecting: false, boundingClientRect: { y: -5 }, target: { id: '1' } },
+    ])
+
+    expect(axios.put).toHaveBeenCalledWith('/api/v1/article/read/101', null, expect.anything())
+    expect(axios.put).toHaveBeenCalledWith('/api/v1/article/read/102', null, expect.anything())
+    expect(axios.put).not.toHaveBeenCalledWith('/api/v1/article/read/103', null, expect.anything())
+    expect(feeds.value).toEqual([{ id: 103, title: 'Third' }])
+
+    setInitialLoad(false)
+  })
+
   it('resolves Deutsche-Welle-style templated image URLs from data-format/data-url', async () => {
     feeds.value = [{
       id: 1,