fix(cover): keep a cover staged in a slot that is locked again before save

A cover staged after unlocking a locked slot, then re-locked before saving,
was silently dropped. The save now leaves that slot open, writes the cover,
then locks it again, and holds the page refetch until the locks are final.

Closes #1915

client/src/features/book/components/detail/tabs/EditMetadataTab.vue

@@ -177,6 +177,7 @@ const {
   isLocked,
   isUpdating: isUpdatingLock,
   replace: replaceLocks,
+  persist: persistLocks,
   toggle,
   lockAll,
   unlockAll,
@@ -343,30 +344,54 @@ const communityRatingLines = computed(() =>
   form.communityRatings.map((rating) => formatCommunityRatingLine(rating, availableMetadataProviders.value ?? [])),
 )
 
+// Held while a save runs, so the parent's refetch reads the book after every write, locks included.
+let heldCoverChanges: (CoverMedium | null)[] | null = null
+
+async function submit() {
+  if (submitDisabled.value) return
+  heldCoverChanges = []
+  try {
+    await saveFormAndCovers()
+  } finally {
+    const held = new Set(heldCoverChanges)
+    heldCoverChanges = null
+    for (const medium of held) emit('coverChanged', medium)
+  }
+}
+
 /**
  * Locks here save with the form, so a pending cover whose slot is locked on the server can only be
  * written after the form has unlocked it. Every other pending cover is written first, and a failure
- * there stops the form save.
+ * there stops the form save. A cover staged while its slot was unlocked here, then locked again, is
+ * still written: the form save leaves that slot open, and it is locked again once the write ends.
  */
-async function submit() {
-  if (submitDisabled.value) return
+async function saveFormAndCovers() {
   const panel = coverPanel.value
   const pendingMedia = panel?.pendingMedia ?? []
   const lockedOnServer = (medium: CoverMedium | null) => props.book.lockedFields.includes(coverLockField(medium))
   if (panel && !(await panel.confirm(pendingMedia.filter((medium) => !lockedOnServer(medium))))) return
 
+  const writeAfterSave = pendingMedia.filter(lockedOnServer)
+  const relockFields: BookMetadataLockField[] = writeAfterSave.map(coverLockField).filter((field) => isLocked(field))
   const locksChanged = locksDirty.value
-  const result = await save(props.book.id, lockedFields.value)
+  const result = await save(
+    props.book.id,
+    lockedFields.value.filter((field) => !relockFields.includes(field)),
+  )
   if (!result) return
   markLocksPersisted(result.book.lockedFields)
+  if (relockFields.length > 0) await replaceLocks(props.book.id, [...result.book.lockedFields, ...relockFields], 'all')
   emit('saved', result.book)
-  if (locksChanged) emit('locksChanged', result.book.lockedFields)
   showSaveResultToast(result.write, result.libraryAutoWriteEnabled)
 
-  const unlockedBySave = pendingMedia.filter((medium) => lockedOnServer(medium) && !result.book.lockedFields.includes(coverLockField(medium)))
-  if (!panel || unlockedBySave.length === 0) return
-  await nextTick()
-  await panel.confirm(unlockedBySave)
+  const unlockedBySave = writeAfterSave.filter((medium) => !result.book.lockedFields.includes(coverLockField(medium)))
+  if (panel && unlockedBySave.length > 0) {
+    await nextTick()
+    await panel.confirm(unlockedBySave)
+  }
+  const relocked = relockFields.length > 0 ? await persistLocks(props.book.id) : null
+  if (relocked) emit('saved', relocked)
+  if (locksChanged) emit('locksChanged', (relocked ?? result.book).lockedFields)
 }
 
 function handleReset() {
@@ -874,7 +899,8 @@ async function handleUnlockAll() {
 }
 
 function handleCoverChanged(medium: CoverMedium | null) {
-  emit('coverChanged', medium)
+  if (heldCoverChanges) heldCoverChanges.push(medium)
+  else emit('coverChanged', medium)
 }
 </script>
 

client/src/features/book/components/detail/tabs/__tests__/EditMetadataTab.spec.ts

@@ -412,6 +412,68 @@ describe('EditMetadataTab cover tiles', () => {
     expect(JSON.parse(String(patchCalls()[0]![1]!.body)).lockedFields).toEqual([])
   })
 
+  it('writes a cover staged while its locked slot was opened here, then locks the slot again', async () => {
+    const wrapper = mountTab(makeBook({ lockedFields: ['title', 'audioCover'] }))
+    await flushPromises()
+    const coverPanelStub = wrapper.getComponent(CoverEditorPanelStub)
+    coverPanelStub.vm.$emit('toggleLock', 'audioCover')
+    await flushPromises()
+    panel.hasPending.value = true
+    panel.pendingMedia.value = ['audio']
+    coverPanelStub.vm.$emit('toggleLock', 'audioCover')
+    await flushPromises()
+
+    const order: string[] = []
+    panel.confirm.mockImplementation(async (media) => {
+      if (!media?.length) return true
+      order.push(`covers:${media.join(',')}`)
+      coverPanelStub.vm.$emit('coverChanged', 'audio')
+      return true
+    })
+    const relockedBook = makeBook({ lockedFields: ['title', 'audioCover'] })
+    vi.mocked(api).mockImplementation(async (url, init) => {
+      if (init?.method !== 'PATCH') return json([])
+      const lockedFields = JSON.parse(String(init.body)).lockedFields
+      if (String(url).endsWith('/metadata-locks')) {
+        order.push(`locks:${lockedFields.join(',')}`)
+        return json(relockedBook)
+      }
+      order.push(`form:${lockedFields.join(',')}`)
+      return json({ book: makeBook({ lockedFields: ['title'] }), write: null, libraryAutoWriteEnabled: false })
+    })
+
+    await saveButton(wrapper).trigger('click')
+    await flushPromises()
+
+    expect(order).toEqual(['form:title', 'covers:audio', 'locks:title,audioCover'])
+    expect(wrapper.emitted('saved')!.at(-1)).toEqual([relockedBook])
+    expect(wrapper.emitted('coverChanged')).toEqual([['audio']])
+    expect(coverPanelStub.props('lockedFields')).toEqual(['title', 'audioCover'])
+  })
+
+  it('locks the slot again when the cover staged in it fails to save', async () => {
+    const wrapper = mountTab(makeBook({ lockedFields: ['audioCover'] }))
+    await flushPromises()
+    const coverPanelStub = wrapper.getComponent(CoverEditorPanelStub)
+    coverPanelStub.vm.$emit('toggleLock', 'audioCover')
+    await flushPromises()
+    panel.hasPending.value = true
+    panel.pendingMedia.value = ['audio']
+    coverPanelStub.vm.$emit('toggleLock', 'audioCover')
+    await flushPromises()
+    panel.confirm.mockImplementation(async (media) => !media?.length)
+    savedBook = makeBook({ lockedFields: [] })
+
+    await saveButton(wrapper).trigger('click')
+    await flushPromises()
+
+    expect(panel.confirm).toHaveBeenLastCalledWith(['audio'])
+    expect(patchCalls().map(([url, init]) => [String(url).split('/').at(-1), JSON.parse(String(init!.body)).lockedFields])).toEqual([
+      ['metadata-and-locks', []],
+      ['metadata-locks', ['audioCover']],
+    ])
+  })
+
   it('clears the unsaved covers with the rest of the form', async () => {
     const wrapper = mountTab(makeBook())
     await flushPromises()

client/src/features/book/composables/__tests__/useMetadataLocks.spec.ts

@@ -174,6 +174,36 @@ describe('useMetadataLocks', () => {
     expect(locksDirty.value).toBe(false)
   })
 
+  it('writes staged lock changes at once when asked, even in deferred mode', async () => {
+    const { load, toggle, persist, lockedFields, locksDirty } = useMetadataLocks({ deferred: true })
+    load(makeBook())
+    await toggle(1, 'cover')
+    apiMock.mockResolvedValueOnce({ ok: true, json: async () => makeBook({ lockedFields: ['cover'] }) })
+
+    const result = await persist(1)
+
+    expect(apiMock).toHaveBeenCalledWith(
+      '/api/v1/books/1/metadata-locks',
+      expect.objectContaining({ method: 'PATCH', body: JSON.stringify({ lockedFields: ['cover'] }) }),
+    )
+    expect(result?.lockedFields).toEqual(['cover'])
+    expect(lockedFields.value).toEqual(['cover'])
+    expect(locksDirty.value).toBe(false)
+  })
+
+  it('keeps staged lock changes when writing them at once fails', async () => {
+    const { load, toggle, persist, lockedFields, locksDirty, error } = useMetadataLocks({ deferred: true })
+    load(makeBook())
+    await toggle(1, 'cover')
+    apiMock.mockResolvedValueOnce({ ok: false, status: 500 })
+
+    expect(await persist(1)).toBeNull()
+
+    expect(error.value).toBe('HTTP 500')
+    expect(lockedFields.value).toEqual(['cover'])
+    expect(locksDirty.value).toBe(true)
+  })
+
   it('marks deferred lock changes as persisted after a successful combined save', async () => {
     const { load, toggle, markPersisted, lockedFields, locksDirty } = useMetadataLocks({ deferred: true })
     load(makeBook())

client/src/features/book/composables/useMetadataLocks.ts

@@ -53,19 +53,30 @@ export function useMetadataLocks(options: UseMetadataLocksOptions = {}) {
     bookId: number,
     nextLockedFields: readonly BookMetadataLockField[],
     scope: BookMetadataLockField | 'all',
+  ): Promise<BookDetail | null> {
+    if (!options.deferred) return send(bookId, nextLockedFields, scope)
+    lockedFields.value = normalizeLockedFields(nextLockedFields)
+    error.value = null
+    return null
+  }
+
+  /** Writes the staged locks now, for a caller whose locks otherwise wait for its form save. */
+  function persist(bookId: number): Promise<BookDetail | null> {
+    return send(bookId, lockedFields.value, 'all')
+  }
+
+  async function send(
+    bookId: number,
+    nextLockedFields: readonly BookMetadataLockField[],
+    scope: BookMetadataLockField | 'all',
   ): Promise<BookDetail | null> {
     updatingField.value = scope
     error.value = null
     try {
-      const normalized = normalizeLockedFields(nextLockedFields)
-      if (options.deferred) {
-        lockedFields.value = normalized
-        return null
-      }
       const res = await api(`/api/v1/books/${bookId}/metadata-locks`, {
         method: 'PATCH',
         headers: { 'Content-Type': 'application/json' },
-        body: JSON.stringify({ lockedFields: normalized }),
+        body: JSON.stringify({ lockedFields: normalizeLockedFields(nextLockedFields) }),
       })
       if (!res.ok) throw new Error(`HTTP ${res.status}`)
       const updated: BookDetail = await res.json()
@@ -108,6 +119,7 @@ export function useMetadataLocks(options: UseMetadataLocksOptions = {}) {
     isLocked,
     isUpdating,
     replace,
+    persist,
     toggle,
     lockAll,
     unlockAll,