From e767358443419253eeed782518d6fc4f675d69fd Mon Sep 17 00:00:00 2001
From: neon <18559658+neonsolstice@users.noreply.github.com>
Date: Wed, 7 Oct 2026 04:56:44 +0000
Subject: [PATCH] feat(library): auto-select sole upload destinations

Remove redundant destination choices when only one book library or folder is available.
Preserve existing Dock targets and cover loading, selection, and failure states with unit tests.

Closes #1362
---
 .../components/BookDockFileSheet.vue          |  73 +-----
 .../components/BookDockFinalizeDialog.vue     |  73 ++----
 .../BookDockSetDestinationDialog.vue          |  65 +-----
 .../__tests__/BookDockFileSheet.spec.ts       | 104 ++++++++-
 .../__tests__/BookDockFinalizeDialog.spec.ts  | 132 ++++++++++-
 .../BookDockSetDestinationDialog.spec.ts      | 103 +++++++++
 .../components/BookDestinationFields.vue      |  77 +++++++
 .../library/components/BookUploadModal.vue    |  76 ++----
 .../__tests__/BookDestinationFields.spec.ts   | 113 +++++++++
 .../__tests__/BookUploadModal.spec.ts         | 158 +++++++++++++
 .../__tests__/useBookDestination.spec.ts      | 217 ++++++++++++++++++
 .../library/composables/useBookDestination.ts |  68 ++++++
 client/src/features/library/test/fixtures.ts  |  42 ++++
 client/src/locales/en.json                    |   7 +
 14 files changed, 1065 insertions(+), 243 deletions(-)
 create mode 100644 client/src/features/book-dock/components/__tests__/BookDockSetDestinationDialog.spec.ts
 create mode 100644 client/src/features/library/components/BookDestinationFields.vue
 create mode 100644 client/src/features/library/components/__tests__/BookDestinationFields.spec.ts
 create mode 100644 client/src/features/library/components/__tests__/BookUploadModal.spec.ts
 create mode 100644 client/src/features/library/composables/__tests__/useBookDestination.spec.ts
 create mode 100644 client/src/features/library/composables/useBookDestination.ts
 create mode 100644 client/src/features/library/test/fixtures.ts

diff --git a/client/src/features/book-dock/components/BookDockFileSheet.vue b/client/src/features/book-dock/components/BookDockFileSheet.vue
index 3e679363c..8e00ece91 100644
--- a/client/src/features/book-dock/components/BookDockFileSheet.vue
+++ b/client/src/features/book-dock/components/BookDockFileSheet.vue
@@ -20,7 +20,8 @@ import BookDockStatusBadge from './BookDockStatusBadge.vue'
 import MetadataMatchWorkspace from '@/features/book/components/metadata-match/MetadataMatchWorkspace.vue'
 import type { MetadataQuery } from '@/features/book/components/metadata-match/MetadataMatchQuery.vue'
 import { useBookDockDetail } from '../composables/useBookDockDetail'
-import { useLibraries } from '@/features/library/composables/useLibraries'
+import { useBookDestination } from '@/features/library/composables/useBookDestination'
+import BookDestinationFields from '@/features/library/components/BookDestinationFields.vue'
 import { useMetadataSearch } from '@/features/book/composables/useMetadataSearch'
 import type { MetadataDiffApply } from '@/features/book/composables/useMetadataDiff'
 import { formatBytes } from '@/lib/formatting'
@@ -37,7 +38,8 @@ const emit = defineEmits<{
 }>()
 
 const { saved, saveError, saveMetadata, setTarget, coverUrl } = useBookDockDetail()
-const { libraries, fetchLibraries: fetchLibs } = useLibraries()
+const destination = useBookDestination({ defaultToFirstLibrary: true })
+const { libraryId: targetLibraryId, folderId: targetFolderId, hasDestination, fetchLibraries: fetchLibs } = destination
 
 const meta = computed(() => props.file.selectedMetadata ?? props.file.embeddedMetadata ?? ({} as BookDockMetadata))
 
@@ -47,15 +49,10 @@ const fetchedCandidate = ref<MetadataCandidate | null>(null)
 
 const sheetWidthClass = computed(() => (metaView.value === 'editor' ? 'sm:w-md lg:w-lg' : 'sm:w-[min(100vw-3rem,80rem)] sm:max-w-none'))
 
-const targetLibraryId = ref<number | null>(null)
-const targetFolderId = ref<number | null>(null)
 const persistedTargetLibraryId = ref<number | null>(null)
 const persistedTargetFolderId = ref<number | null>(null)
 const finishing = ref(false)
 
-const selectedLibrary = computed(() => libraries.value.find((l) => l.id === targetLibraryId.value))
-const folders = computed(() => selectedLibrary.value?.folders ?? [])
-
 const form = reactive({
   title: '',
   subtitle: '',
@@ -101,29 +98,13 @@ watch(
     selectedCoverUrl.value = m.coverUrl ?? ''
     metaView.value = 'editor'
 
-    targetLibraryId.value = props.file.targetLibraryId ?? libraries.value[0]?.id ?? null
-    const lib = libraries.value.find((l) => l.id === targetLibraryId.value)
-    targetFolderId.value = props.file.targetFolderId ?? lib?.folders?.[0]?.id ?? null
+    destination.reset(props.file.targetLibraryId, props.file.targetFolderId)
     persistedTargetLibraryId.value = props.file.targetLibraryId
     persistedTargetFolderId.value = props.file.targetFolderId
   },
   { immediate: true },
 )
 
-watch(
-  () => libraries.value,
-  (libs) => {
-    if (!libs.length) return
-    if (targetLibraryId.value === null) {
-      targetLibraryId.value = props.file.targetLibraryId ?? libs[0]?.id ?? null
-    }
-    if (targetFolderId.value === null) {
-      const lib = libs.find((l) => l.id === targetLibraryId.value)
-      targetFolderId.value = props.file.targetFolderId ?? lib?.folders?.[0]?.id ?? null
-    }
-  },
-)
-
 let debounceTimer: ReturnType<typeof setTimeout> | null = null
 let pendingTargetSave: Promise<BookDockFile | null> | null = null
 
@@ -182,22 +163,8 @@ function onPublishedYearChange() {
   onFieldChange()
 }
 
-async function onLibraryChange(event: Event) {
-  const raw = Number((event.target as HTMLSelectElement).value)
-  const id = Number.isFinite(raw) && raw > 0 ? raw : null
-  targetLibraryId.value = id
-  const lib = libraries.value.find((l) => l.id === targetLibraryId.value)
-  targetFolderId.value = lib?.folders?.[0]?.id ?? null
-  await persistTarget()
-}
-
-async function onFolderChange(event: Event) {
-  const raw = Number((event.target as HTMLSelectElement).value)
-  targetFolderId.value = Number.isFinite(raw) && raw > 0 ? raw : null
-  await persistTarget()
-}
-
 async function persistTarget(): Promise<BookDockFile | null> {
+  if (!hasDestination.value) return null
   const libraryId = targetLibraryId.value
   const folderId = targetFolderId.value
   const previousSave = pendingTargetSave
@@ -627,28 +594,12 @@ onMounted(() => {
             </label>
           </div>
 
-          <div class="space-y-3 pt-1">
-            <label class="block">
-              <span class="text-xs font-medium text-muted-foreground">{{ t('bookDock.destinationLibrary') }}</span>
-              <select
-                class="mt-1 w-full h-8 rounded-lg border border-input bg-background px-3 text-sm outline-none focus:ring-1 focus:ring-ring"
-                :value="targetLibraryId ?? ''"
-                @change="onLibraryChange"
-              >
-                <option v-for="lib in libraries" :key="lib.id" :value="lib.id">{{ lib.name }}</option>
-              </select>
-            </label>
-            <label class="block">
-              <span class="text-xs font-medium text-muted-foreground">{{ t('bookDock.destinationFolder') }}</span>
-              <select
-                class="mt-1 w-full h-8 rounded-lg border border-input bg-background px-3 text-sm outline-none focus:ring-1 focus:ring-ring"
-                :value="targetFolderId ?? ''"
-                @change="onFolderChange"
-              >
-                <option v-for="folder in folders" :key="folder.id" :value="folder.id">{{ folder.path }}</option>
-              </select>
-            </label>
-          </div>
+          <BookDestinationFields
+            :destination="destination"
+            :library-label="t('bookDock.destinationLibrary')"
+            :folder-label="t('bookDock.destinationFolder')"
+            @change="persistTarget"
+          />
 
           <p class="text-xs text-muted-foreground">{{ t('bookDock.sheet.added', { date: formatDate(file.createdAt) }) }}</p>
         </div>
diff --git a/client/src/features/book-dock/components/BookDockFinalizeDialog.vue b/client/src/features/book-dock/components/BookDockFinalizeDialog.vue
index 4b25e3800..1fcbec04a 100644
--- a/client/src/features/book-dock/components/BookDockFinalizeDialog.vue
+++ b/client/src/features/book-dock/components/BookDockFinalizeDialog.vue
@@ -6,7 +6,8 @@ import { X, Check, AlertCircle, Copy, Loader2, ExternalLink, ChevronDown, FileTe
 import type { BookDockDiscardDuplicatesResult, BookDockFinalizePreviewResult } from '@bookorbit/types'
 
 import { api } from '@/lib/api'
-import { useLibraries } from '@/features/library/composables/useLibraries'
+import { useBookDestination } from '@/features/library/composables/useBookDestination'
+import BookDestinationFields from '@/features/library/components/BookDestinationFields.vue'
 import { useBookDockFinalize } from '../composables/useBookDockFinalize'
 
 const { t } = useI18n()
@@ -42,11 +43,10 @@ const emit = defineEmits<{
 }>()
 
 const router = useRouter()
-const { libraries, fetchLibraries, refreshLibraries } = useLibraries()
+const destination = useBookDestination({ defaultToFirstLibrary: true })
+const { libraryId: defaultLibraryId, folderId: defaultFolderId, hasDestination, fetchLibraries, refreshLibraries } = destination
 const { result, loading, error, finalize, reset } = useBookDockFinalize()
 
-const defaultLibraryId = ref<number | null>(null)
-const defaultFolderId = ref<number | null>(null)
 const expandedErrors = ref<Set<number>>(new Set())
 const reimportingIds = reactive(new Set<number>())
 const renameInputs = ref<Map<number, string>>(new Map())
@@ -109,7 +109,7 @@ function effectiveSelectionPayload(): {
 function finalizePayload(): FinalizePayload {
   return {
     ...effectiveSelectionPayload(),
-    ...(requiresDefaultDestination.value && defaultLibraryId.value !== null && defaultFolderId.value !== null
+    ...(requiresDefaultDestination.value && hasDestination.value && defaultLibraryId.value !== null && defaultFolderId.value !== null
       ? {
           defaultLibraryId: defaultLibraryId.value,
           defaultFolderId: defaultFolderId.value,
@@ -157,53 +157,27 @@ const namePreview = ref<{ fileId: number; fileName: string; newName: string }[]>
 const previewLoading = ref(false)
 let previewReqSeq = 0
 
-const selectedLibrary = computed(() => libraries.value.find((l) => l.id === defaultLibraryId.value))
-const folders = computed(() => selectedLibrary.value?.folders ?? [])
-
 const requiresDefaultDestination = computed(() => (selectionSummary.value?.withoutDestination ?? props.selectionCount) > 0)
 const canStart = computed(() => {
   if (effectiveSelectionCount.value <= 0) return false
   if (!selectionSummary.value) return false
   if (!requiresDefaultDestination.value) return true
-  return defaultLibraryId.value !== null && defaultFolderId.value !== null
+  return hasDestination.value
 })
 
 onMounted(async () => {
   await Promise.all([fetchLibraries(), fetchSelectionSummary()])
-  const first = libraries.value[0]
-  if (requiresDefaultDestination.value && first) {
-    defaultLibraryId.value = first.id
-    const firstFolder = first.folders?.[0]
-    if (firstFolder) defaultFolderId.value = firstFolder.id
-  }
   void fetchFinalizePreview()
 })
 
-function onLibraryChange(event: Event) {
-  const raw = Number((event.target as HTMLSelectElement).value)
-  const id = Number.isFinite(raw) && raw > 0 ? raw : null
-  if (id === null) {
-    defaultLibraryId.value = null
-    defaultFolderId.value = null
-    return
-  }
-  defaultLibraryId.value = id
-  const lib = libraries.value.find((l) => l.id === id)
-  defaultFolderId.value = lib?.folders?.[0]?.id ?? null
-}
-
-function onFolderChange(event: Event) {
-  const raw = Number((event.target as HTMLSelectElement).value)
-  defaultFolderId.value = Number.isFinite(raw) && raw > 0 ? raw : null
-}
-
 function syncNamePreviewFromFinalizePreview(preview: BookDockFinalizePreviewResult | null) {
   namePreview.value =
     preview?.items.filter((item) => !!item.newName).map((item) => ({ fileId: item.fileId, fileName: item.fileName, newName: item.newName! })) ?? []
 }
 
 async function fetchFinalizePreview() {
-  if (requiresDefaultDestination.value && (defaultLibraryId.value === null || defaultFolderId.value === null)) {
+  if (!selectionSummary.value || (requiresDefaultDestination.value && !hasDestination.value)) {
+    ++previewReqSeq
     finalizePreview.value = null
     namePreview.value = []
     previewLoading.value = false
@@ -264,7 +238,7 @@ async function fetchSelectionSummary() {
   selectionSummary.value = { total: props.selectionCount, withDestination: 0, withoutDestination: props.selectionCount }
 }
 
-watch([defaultLibraryId, defaultFolderId, requiresDefaultDestination], () => {
+watch([defaultLibraryId, defaultFolderId, requiresDefaultDestination, hasDestination], () => {
   void fetchFinalizePreview()
 })
 
@@ -433,29 +407,12 @@ async function handleDiscardResultDuplicates() {
 
           <p v-if="finalizePreviewError" class="text-xs text-red-500 bg-red-500/10 rounded-lg p-2">{{ finalizePreviewError }}</p>
 
-          <div v-if="requiresDefaultDestination" class="space-y-3">
-            <label class="block">
-              <span class="text-xs font-medium text-muted-foreground">{{ t('bookDock.finalizeDialog.defaultDestinationLibrary') }}</span>
-              <select
-                class="mt-1 w-full h-9 rounded-lg border border-input bg-background px-3 text-sm outline-none focus:ring-1 focus:ring-ring"
-                :value="defaultLibraryId ?? ''"
-                @change="onLibraryChange"
-              >
-                <option v-for="lib in libraries" :key="lib.id" :value="lib.id">{{ lib.name }}</option>
-              </select>
-            </label>
-
-            <label class="block">
-              <span class="text-xs font-medium text-muted-foreground">{{ t('bookDock.finalizeDialog.defaultDestinationFolder') }}</span>
-              <select
-                class="mt-1 w-full h-9 rounded-lg border border-input bg-background px-3 text-sm outline-none focus:ring-1 focus:ring-ring"
-                :value="defaultFolderId ?? ''"
-                @change="onFolderChange"
-              >
-                <option v-for="folder in folders" :key="folder.id" :value="folder.id">{{ folder.path }}</option>
-              </select>
-            </label>
-          </div>
+          <BookDestinationFields
+            v-if="requiresDefaultDestination"
+            :destination="destination"
+            :library-label="t('bookDock.finalizeDialog.defaultDestinationLibrary')"
+            :folder-label="t('bookDock.finalizeDialog.defaultDestinationFolder')"
+          />
 
           <div v-if="namePreview.length || previewLoading" class="space-y-1.5">
             <div class="flex items-center gap-1.5">
diff --git a/client/src/features/book-dock/components/BookDockSetDestinationDialog.vue b/client/src/features/book-dock/components/BookDockSetDestinationDialog.vue
index 33f5a3674..f0235d626 100644
--- a/client/src/features/book-dock/components/BookDockSetDestinationDialog.vue
+++ b/client/src/features/book-dock/components/BookDockSetDestinationDialog.vue
@@ -3,7 +3,8 @@ import { computed, onMounted, ref } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { X, Loader2, FolderPlus } from '@lucide/vue'
 import { api } from '@/lib/api'
-import { useLibraries } from '@/features/library/composables/useLibraries'
+import { useBookDestination } from '@/features/library/composables/useBookDestination'
+import BookDestinationFields from '@/features/library/components/BookDestinationFields.vue'
 
 const { t } = useI18n()
 
@@ -25,44 +26,18 @@ const emit = defineEmits<{
   updated: []
 }>()
 
-const { libraries, fetchLibraries } = useLibraries()
+const destination = useBookDestination({ defaultToFirstLibrary: true })
+const { libraryId: targetLibraryId, folderId: targetFolderId, hasDestination, fetchLibraries } = destination
 const loading = ref(false)
 const error = ref<string | null>(null)
 const result = ref<{ total: number; updated: number; failed: number } | null>(null)
 
-const targetLibraryId = ref<number | null>(null)
-const targetFolderId = ref<number | null>(null)
+const canApply = computed(() => hasDestination.value && !loading.value)
 
-const selectedLibrary = computed(() => libraries.value.find((l) => l.id === targetLibraryId.value))
-const folders = computed(() => selectedLibrary.value?.folders ?? [])
-const canApply = computed(() => targetLibraryId.value !== null && targetFolderId.value !== null && !loading.value)
-
-onMounted(async () => {
-  await fetchLibraries()
-  const first = libraries.value[0]
-  if (!first) return
-  targetLibraryId.value = first.id
-  targetFolderId.value = first.folders?.[0]?.id ?? null
+onMounted(() => {
+  void fetchLibraries()
 })
 
-function onLibraryChange(event: Event) {
-  const raw = Number((event.target as HTMLSelectElement).value)
-  const id = Number.isFinite(raw) && raw > 0 ? raw : null
-  if (id === null) {
-    targetLibraryId.value = null
-    targetFolderId.value = null
-    return
-  }
-  targetLibraryId.value = id
-  const lib = libraries.value.find((l) => l.id === id)
-  targetFolderId.value = lib?.folders?.[0]?.id ?? null
-}
-
-function onFolderChange(event: Event) {
-  const raw = Number((event.target as HTMLSelectElement).value)
-  targetFolderId.value = Number.isFinite(raw) && raw > 0 ? raw : null
-}
-
 async function applyDestination() {
   if (!canApply.value) return
   loading.value = true
@@ -114,27 +89,11 @@ function handleClose() {
         </div>
 
         <div v-if="!result" class="px-5 py-4 space-y-4">
-          <label class="block">
-            <span class="text-xs font-medium text-muted-foreground">{{ t('bookDock.destinationLibrary') }}</span>
-            <select
-              class="mt-1 w-full h-9 rounded-lg border border-input bg-background px-3 text-sm outline-none focus:ring-1 focus:ring-ring"
-              :value="targetLibraryId ?? ''"
-              @change="onLibraryChange"
-            >
-              <option v-for="lib in libraries" :key="lib.id" :value="lib.id">{{ lib.name }}</option>
-            </select>
-          </label>
-
-          <label class="block">
-            <span class="text-xs font-medium text-muted-foreground">{{ t('bookDock.destinationFolder') }}</span>
-            <select
-              class="mt-1 w-full h-9 rounded-lg border border-input bg-background px-3 text-sm outline-none focus:ring-1 focus:ring-ring"
-              :value="targetFolderId ?? ''"
-              @change="onFolderChange"
-            >
-              <option v-for="folder in folders" :key="folder.id" :value="folder.id">{{ folder.path }}</option>
-            </select>
-          </label>
+          <BookDestinationFields
+            :destination="destination"
+            :library-label="t('bookDock.destinationLibrary')"
+            :folder-label="t('bookDock.destinationFolder')"
+          />
 
           <p v-if="error" class="text-xs text-red-500 bg-red-500/10 rounded-lg p-2">{{ error }}</p>
 
diff --git a/client/src/features/book-dock/components/__tests__/BookDockFileSheet.spec.ts b/client/src/features/book-dock/components/__tests__/BookDockFileSheet.spec.ts
index 994431cf7..f34b5798b 100644
--- a/client/src/features/book-dock/components/__tests__/BookDockFileSheet.spec.ts
+++ b/client/src/features/book-dock/components/__tests__/BookDockFileSheet.spec.ts
@@ -1,10 +1,11 @@
 import { flushPromises, shallowMount } from '@vue/test-utils'
 import { defineComponent, reactive, ref } from 'vue'
-import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import type { BookDockFile, Library, MetadataCandidate } from '@bookorbit/types'
+import { i18n } from '@/i18n'
 import BookDockFileSheet from '../BookDockFileSheet.vue'
 
-type LibraryOption = Pick<Library, 'id' | 'name'> & {
+type LibraryOption = Pick<Library, 'id' | 'name' | 'type'> & {
   folders: Array<Pick<Library['folders'][number], 'id' | 'path'>>
 }
 
@@ -18,6 +19,8 @@ const mocks = vi.hoisted(() => ({
   libraries: [] as LibraryOption[],
 }))
 
+const libraryOptions = ref<LibraryOption[]>([])
+
 vi.mock('../../composables/useBookDockDetail', () => ({
   useBookDockDetail: () => ({
     saved: ref(false),
@@ -30,8 +33,11 @@ vi.mock('../../composables/useBookDockDetail', () => ({
 
 vi.mock('@/features/library/composables/useLibraries', () => ({
   useLibraries: () => ({
-    libraries: ref(mocks.libraries),
+    libraries: libraryOptions,
     fetchLibraries: mocks.fetchLibraries,
+    loaded: ref(true),
+    loading: ref(false),
+    error: ref(null),
   }),
 }))
 
@@ -92,16 +98,22 @@ function makeFile(overrides: Partial<BookDockFile> = {}): BookDockFile {
   }
 }
 
+const wrappers: ReturnType<typeof shallowMount>[] = []
+afterEach(() => wrappers.splice(0).forEach((wrapper) => wrapper.unmount()))
+
 function mountSheet(file: BookDockFile) {
-  return shallowMount(BookDockFileSheet, {
+  const wrapper = shallowMount(BookDockFileSheet, {
     props: { file },
     global: {
       stubs: {
         MetadataMatchWorkspace: WorkspaceStub,
         BookDockStatusBadge: true,
+        BookDestinationFields: false,
       },
     },
   })
+  wrappers.push(wrapper)
+  return wrapper
 }
 
 async function openSearchAndReadDefaults(file: BookDockFile): Promise<Record<string, string | undefined>> {
@@ -114,6 +126,7 @@ async function openSearchAndReadDefaults(file: BookDockFile): Promise<Record<str
 
 describe('BookDockFileSheet', () => {
   beforeEach(() => {
+    i18n.global.locale.value = 'en'
     vi.clearAllMocks()
     mocks.fetchLibraries.mockResolvedValue(undefined)
     mocks.loadProviders.mockResolvedValue(undefined)
@@ -121,6 +134,7 @@ describe('BookDockFileSheet', () => {
     mocks.setTarget.mockResolvedValue(null)
     mocks.filteredResults.length = 0
     mocks.libraries.length = 0
+    libraryOptions.value = mocks.libraries
   })
 
   it.each([
@@ -303,16 +317,17 @@ describe('BookDockFileSheet', () => {
   it('persists the visible default destination when finishing metadata edits', async () => {
     mocks.libraries.push({
       id: 7,
+      type: 'books',
       name: 'Novels',
       folders: [{ id: 70, path: '/library/novels' }],
     })
     const updatedFile = makeFile({ targetLibraryId: 7, targetFolderId: 70 })
     mocks.setTarget.mockResolvedValue(updatedFile)
     const wrapper = mountSheet(makeFile())
-    const [librarySelect, folderSelect] = wrapper.findAll<HTMLSelectElement>('select')
-
-    expect(librarySelect!.element.value).toBe('7')
-    expect(folderSelect!.element.value).toBe('70')
+    await flushPromises()
+    expect(wrapper.findAll('select')).toHaveLength(0)
+    expect(wrapper.text()).toContain('Novels')
+    expect(wrapper.text()).toContain('/library/novels')
 
     const doneButton = wrapper.findAll('button').find((button) => button.text().trim() === 'Done')
     await doneButton!.trigger('click')
@@ -326,6 +341,7 @@ describe('BookDockFileSheet', () => {
   it('does not save an unchanged destination again when finishing', async () => {
     mocks.libraries.push({
       id: 7,
+      type: 'books',
       name: 'Novels',
       folders: [{ id: 70, path: '/library/novels' }],
     })
@@ -343,11 +359,13 @@ describe('BookDockFileSheet', () => {
     mocks.libraries.push(
       {
         id: 7,
+        type: 'books',
         name: 'Novels',
         folders: [{ id: 70, path: '/library/novels' }],
       },
       {
         id: 8,
+        type: 'books',
         name: 'Comics',
         folders: [{ id: 80, path: '/library/comics' }],
       },
@@ -375,6 +393,7 @@ describe('BookDockFileSheet', () => {
   it('keeps the sheet open when the visible destination cannot be saved', async () => {
     mocks.libraries.push({
       id: 7,
+      type: 'books',
       name: 'Novels',
       folders: [{ id: 70, path: '/library/novels' }],
     })
@@ -389,4 +408,73 @@ describe('BookDockFileSheet', () => {
     expect(wrapper.emitted('updated')).toBeUndefined()
     expect(wrapper.emitted('close')).toBeUndefined()
   })
+  it('selects a delayed sole library and persists it only when Done is clicked', async () => {
+    mocks.fetchLibraries.mockImplementation(async () => {
+      libraryOptions.value = [{ id: 7, type: 'books', name: 'Novels', folders: [{ id: 70, path: '/books/novels' }] }]
+    })
+    mocks.setTarget.mockResolvedValue(makeFile({ targetLibraryId: 7, targetFolderId: 70 }))
+    const wrapper = mountSheet(makeFile())
+    await flushPromises()
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).toContain('Novels')
+    expect(mocks.setTarget).not.toHaveBeenCalled()
+    await wrapper
+      .findAll('button')
+      .find((button) => button.text().trim() === 'Done')!
+      .trigger('click')
+    await flushPromises()
+    expect(mocks.setTarget).toHaveBeenCalledExactlyOnceWith(1, 7, 70)
+  })
+
+  it('preserves a saved non-first folder and offers the other folders', async () => {
+    mocks.libraries.push({
+      id: 7,
+      type: 'books',
+      name: 'Novels',
+      folders: [
+        { id: 70, path: '/books/first' },
+        { id: 71, path: '/books/second' },
+      ],
+    })
+    const wrapper = mountSheet(makeFile({ targetLibraryId: 7, targetFolderId: 71 }))
+    await flushPromises()
+    expect(wrapper.findAll('select')).toHaveLength(1)
+    expect(wrapper.get<HTMLSelectElement>('select').element.value).toBe('71')
+    await wrapper.get('select').setValue('70')
+    await flushPromises()
+    expect(mocks.setTarget).toHaveBeenCalledWith(1, 7, 70)
+  })
+
+  it('uses the next file destination when switching files in an open sheet', async () => {
+    mocks.libraries.push(
+      { id: 7, type: 'books', name: 'Novels', folders: [{ id: 70, path: '/books/novels' }] },
+      { id: 8, type: 'books', name: 'Comics', folders: [{ id: 80, path: '/books/comics' }] },
+    )
+    const wrapper = mountSheet(makeFile({ targetLibraryId: 7, targetFolderId: 70 }))
+    await wrapper.setProps({ file: makeFile({ id: 2, targetLibraryId: 8, targetFolderId: 80 }) })
+    await flushPromises()
+    expect(wrapper.get<HTMLSelectElement>('select').element.value).toBe('8')
+    expect(wrapper.text()).toContain('/books/comics')
+    await wrapper
+      .findAll('button')
+      .find((button) => button.text().trim() === 'Done')!
+      .trigger('click')
+    await flushPromises()
+    expect(mocks.setTarget).not.toHaveBeenCalled()
+    expect(wrapper.emitted('close')).toEqual([[]])
+  })
+
+  it('does not overwrite an unavailable saved destination with the sole library', async () => {
+    mocks.libraries.push({ id: 7, type: 'books', name: 'Novels', folders: [{ id: 70, path: '/books/novels' }] })
+    const wrapper = mountSheet(makeFile({ targetLibraryId: 99, targetFolderId: 990 }))
+    await flushPromises()
+    expect(wrapper.get<HTMLSelectElement>('select').element.value).toBe('')
+    await wrapper
+      .findAll('button')
+      .find((button) => button.text().trim() === 'Done')!
+      .trigger('click')
+    await flushPromises()
+    expect(mocks.setTarget).not.toHaveBeenCalled()
+    expect(wrapper.emitted('close')).toEqual([[]])
+  })
 })
diff --git a/client/src/features/book-dock/components/__tests__/BookDockFinalizeDialog.spec.ts b/client/src/features/book-dock/components/__tests__/BookDockFinalizeDialog.spec.ts
index 1ce1ee293..a8f060377 100644
--- a/client/src/features/book-dock/components/__tests__/BookDockFinalizeDialog.spec.ts
+++ b/client/src/features/book-dock/components/__tests__/BookDockFinalizeDialog.spec.ts
@@ -1,9 +1,12 @@
 import { flushPromises, mount } from '@vue/test-utils'
-import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { ref } from 'vue'
 import type { BookDockFinalizeResult } from '@bookorbit/types'
 import BookDockFinalizeDialog from '../BookDockFinalizeDialog.vue'
+import { i18n } from '@/i18n'
+import { makeLibrary } from '@/features/library/test/fixtures'
 
+const selectionSummary = ref({ total: 2, withDestination: 0, withoutDestination: 2 })
 const apiMock = vi.fn<(...args: unknown[]) => Promise<Response>>()
 const finalizeResult = ref<BookDockFinalizeResult | null>(null)
 const finalizeLoading = ref(false)
@@ -11,6 +14,12 @@ const finalizeError = ref<string | null>(null)
 const finalizeMock = vi.fn<(...args: unknown[]) => Promise<void>>()
 const resetMock = vi.fn<() => void>()
 const fetchLibrariesMock = vi.fn<() => Promise<void>>()
+const libraryOptions = ref([
+  makeLibrary({ id: 2, name: 'Main', folders: [{ id: 3, path: '/books', role: 'downloads', createdAt: '2026-01-01T00:00:00.000Z' }] }),
+])
+const librariesLoaded = ref(true)
+const librariesLoading = ref(false)
+const librariesError = ref<string | null>(null)
 const refreshLibrariesMock = vi.fn<() => void>()
 
 vi.mock('vue-router', () => ({
@@ -25,7 +34,10 @@ vi.mock('@/lib/api', () => ({
 
 vi.mock('@/features/library/composables/useLibraries', () => ({
   useLibraries: () => ({
-    libraries: ref([{ id: 2, name: 'Main', folders: [{ id: 3, path: '/books' }] }]),
+    libraries: libraryOptions,
+    loaded: librariesLoaded,
+    loading: librariesLoading,
+    error: librariesError,
     fetchLibraries: fetchLibrariesMock,
     refreshLibraries: refreshLibrariesMock,
   }),
@@ -49,8 +61,11 @@ function jsonResponse(body: unknown, status = 200): Response {
   } as unknown as Response
 }
 
+const wrappers: ReturnType<typeof mount>[] = []
+afterEach(() => wrappers.splice(0).forEach((wrapper) => wrapper.unmount()))
+
 function mountDialog() {
-  return mount(BookDockFinalizeDialog, {
+  const wrapper = mount(BookDockFinalizeDialog, {
     props: {
       selectionPayload: { fileIds: [10, 11] },
       selectionCount: 2,
@@ -61,10 +76,20 @@ function mountDialog() {
       },
     },
   })
+  wrappers.push(wrapper)
+  return wrapper
 }
 
 describe('BookDockFinalizeDialog', () => {
   beforeEach(() => {
+    i18n.global.locale.value = 'en'
+    libraryOptions.value = [
+      makeLibrary({ id: 2, name: 'Main', folders: [{ id: 3, path: '/books', role: 'downloads', createdAt: '2026-01-01T00:00:00.000Z' }] }),
+    ]
+    selectionSummary.value = { total: 2, withDestination: 0, withoutDestination: 2 }
+    librariesLoaded.value = true
+    librariesLoading.value = false
+    librariesError.value = null
     apiMock.mockReset()
     finalizeResult.value = null
     finalizeLoading.value = false
@@ -77,7 +102,7 @@ describe('BookDockFinalizeDialog', () => {
 
     apiMock.mockImplementation(async (url) => {
       if (url === '/api/v1/book-dock/files/selection-summary') {
-        return jsonResponse({ total: 2, withDestination: 0, withoutDestination: 2 })
+        return jsonResponse(selectionSummary.value)
       }
 
       if (url === '/api/v1/book-dock/finalize/preview') {
@@ -177,4 +202,103 @@ describe('BookDockFinalizeDialog', () => {
     expect(wrapper.text()).not.toContain('Import anyway')
     expect(wrapper.find('input[type="text"]').exists()).toBe(true)
   })
+  function startButton(wrapper: ReturnType<typeof mountDialog>) {
+    return wrapper.findAll('button').find((button) => button.text().trim() === 'Start')!
+  }
+
+  it('shows a sole destination as text and files only after explicit confirmation', async () => {
+    const wrapper = mountDialog()
+    await flushPromises()
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).toContain('Main')
+    expect(wrapper.text()).toContain('/books')
+    expect(finalizeMock).not.toHaveBeenCalled()
+    await startButton(wrapper).trigger('click')
+    expect(finalizeMock).toHaveBeenCalledExactlyOnceWith({ fileIds: [10, 11], defaultLibraryId: 2, defaultFolderId: 3 })
+  })
+
+  it('keeps multiple folders selectable and uses the chosen folder in preview and finalization', async () => {
+    libraryOptions.value[0]!.folders.push({ ...libraryOptions.value[0]!.folders[0]!, id: 4, path: '/books/second' })
+    const wrapper = mountDialog()
+    await flushPromises()
+    expect(wrapper.findAll('select')).toHaveLength(1)
+    await wrapper.get('select').setValue('4')
+    await flushPromises()
+    const previewCalls = apiMock.mock.calls.filter(([url]) => url === '/api/v1/book-dock/finalize/preview')
+    const body = JSON.parse((previewCalls.at(-1)![1] as RequestInit).body as string)
+    expect(body.defaultFolderId).toBe(4)
+    await startButton(wrapper).trigger('click')
+    expect(finalizeMock).toHaveBeenCalledWith({ fileIds: [10, 11], defaultLibraryId: 2, defaultFolderId: 4 })
+  })
+
+  it('preserves the first-library default with multiple choices and excludes podcasts', async () => {
+    libraryOptions.value.unshift(makeLibrary({ id: 1, type: 'podcasts', name: 'Podcasts' }))
+    libraryOptions.value.push(makeLibrary({ id: 5, name: 'Comics' }))
+    const wrapper = mountDialog()
+    await flushPromises()
+    expect(wrapper.get<HTMLSelectElement>('select').element.value).toBe('2')
+    expect(wrapper.text()).not.toContain('Podcasts')
+    await wrapper.get('select').setValue('5')
+    await flushPromises()
+    await startButton(wrapper).trigger('click')
+    expect(finalizeMock).toHaveBeenCalledWith({ fileIds: [10, 11], defaultLibraryId: 5, defaultFolderId: 30 })
+  })
+
+  it.each(['empty', 'folderless', 'failed', 'loading'])('blocks filing and preview for a %s fallback destination', async (scenario) => {
+    if (scenario === 'empty') libraryOptions.value = []
+    if (scenario === 'folderless') libraryOptions.value[0]!.folders = []
+    if (scenario === 'failed') librariesError.value = 'HTTP 503'
+    if (scenario === 'loading') librariesLoading.value = true
+    const wrapper = mountDialog()
+    await flushPromises()
+    expect(startButton(wrapper).attributes('disabled')).toBeDefined()
+    await startButton(wrapper).trigger('click')
+    expect(finalizeMock).not.toHaveBeenCalled()
+    expect(apiMock.mock.calls.some(([url]) => url === '/api/v1/book-dock/finalize/preview')).toBe(false)
+  })
+
+  it('does not send a fallback when all files already carry destinations', async () => {
+    selectionSummary.value = { total: 2, withDestination: 2, withoutDestination: 0 }
+    const wrapper = mountDialog()
+    await flushPromises()
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).not.toContain('/books')
+    await startButton(wrapper).trigger('click')
+    expect(finalizeMock).toHaveBeenCalledExactlyOnceWith({ fileIds: [10, 11] })
+    const previewCall = apiMock.mock.calls.find(([url]) => url === '/api/v1/book-dock/finalize/preview')!
+    expect(JSON.parse((previewCall[1] as RequestInit).body as string)).toEqual({ fileIds: [10, 11] })
+  })
+  it('ignores a late preview after the selected destination becomes unavailable', async () => {
+    const completePreviews: Array<(response: Response) => void> = []
+    apiMock.mockImplementation(async (url) => {
+      if (url === '/api/v1/book-dock/files/selection-summary') return jsonResponse(selectionSummary.value)
+      return new Promise<Response>((resolve) => {
+        completePreviews.push(resolve)
+      })
+    })
+    const wrapper = mountDialog()
+    await flushPromises()
+    expect(completePreviews.length).toBeGreaterThan(0)
+    libraryOptions.value[0]!.folders = []
+    await flushPromises()
+    for (const complete of completePreviews) {
+      complete(
+        jsonResponse({
+          total: 2,
+          ready: 2,
+          duplicates: 0,
+          destinationConflicts: 0,
+          missingDestination: 0,
+          blocked: 0,
+          truncated: false,
+          itemLimit: 200,
+          items: [{ fileId: 10, fileName: 'stale.epub', newName: 'stale-name.epub', status: 'ready' }],
+        }),
+      )
+    }
+    await flushPromises()
+    expect(wrapper.text()).not.toContain('stale-name.epub')
+    expect(startButton(wrapper).attributes('disabled')).toBeDefined()
+    expect(finalizeMock).not.toHaveBeenCalled()
+  })
 })
diff --git a/client/src/features/book-dock/components/__tests__/BookDockSetDestinationDialog.spec.ts b/client/src/features/book-dock/components/__tests__/BookDockSetDestinationDialog.spec.ts
new file mode 100644
index 000000000..b8500990a
--- /dev/null
+++ b/client/src/features/book-dock/components/__tests__/BookDockSetDestinationDialog.spec.ts
@@ -0,0 +1,103 @@
+import { flushPromises, mount, type VueWrapper } from '@vue/test-utils'
+import { ref } from 'vue'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { Library } from '@bookorbit/types'
+import { i18n } from '@/i18n'
+import { makeLibrary } from '@/features/library/test/fixtures'
+import BookDockSetDestinationDialog from '../BookDockSetDestinationDialog.vue'
+
+const libraries = ref<Library[]>([])
+const loaded = ref(true)
+const loading = ref(false)
+const error = ref<string | null>(null)
+const fetchLibraries = vi.fn<() => Promise<void>>()
+const api = vi.fn<(...args: unknown[]) => Promise<Response>>()
+vi.mock('@/features/library/composables/useLibraries', () => ({
+  useLibraries: () => ({ libraries, loaded, loading, error, fetchLibraries, refreshLibraries: vi.fn<() => Promise<void>>() }),
+}))
+vi.mock('@/lib/api', () => ({ api: (...args: unknown[]) => api(...args) }))
+let wrapper: VueWrapper
+function mountDialog() {
+  wrapper = mount(BookDockSetDestinationDialog, {
+    props: { selectionPayload: { selectAll: true, excludedIds: [12], search: 'Dune' }, selectionCount: 2 },
+    global: { stubs: { Teleport: true } },
+  })
+}
+function applyButton() {
+  return wrapper.findAll('button').find((button) => button.text().trim() === 'Apply')!
+}
+
+beforeEach(() => {
+  i18n.global.locale.value = 'en'
+  libraries.value = [makeLibrary()]
+  loaded.value = true
+  loading.value = false
+  error.value = null
+  fetchLibraries.mockReset().mockResolvedValue(undefined)
+  api.mockReset().mockResolvedValue({ ok: true, json: async () => ({ total: 2, updated: 2, failed: 0 }) } as Response)
+})
+afterEach(() => wrapper?.unmount())
+
+describe('BookDockSetDestinationDialog', () => {
+  it('shows a sole destination as text and applies it to the unchanged selection payload', async () => {
+    mountDialog()
+    await flushPromises()
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).toContain('Main Library')
+    expect(wrapper.text()).toContain('/books')
+    expect(api).not.toHaveBeenCalled()
+    await applyButton().trigger('click')
+    expect(api).toHaveBeenCalledExactlyOnceWith('/api/v1/book-dock/files/set-target', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ selectAll: true, excludedIds: [12], search: 'Dune', targetLibraryId: 3, targetFolderId: 30 }),
+    })
+  })
+
+  it('keeps multiple folders selectable without requiring a library choice', async () => {
+    libraries.value[0]!.folders.push({ ...libraries.value[0]!.folders[0]!, id: 31, path: '/books/second' })
+    mountDialog()
+    await flushPromises()
+    expect(wrapper.findAll('select')).toHaveLength(1)
+    await wrapper.get('select').setValue('31')
+    await applyButton().trigger('click')
+    expect(JSON.parse((api.mock.calls[0]![1] as RequestInit).body as string).targetFolderId).toBe(31)
+  })
+
+  it('keeps the existing first-library default and updates the folder when choosing another', async () => {
+    libraries.value.unshift(makeLibrary({ id: 1, type: 'podcasts', name: 'Podcasts' }))
+    libraries.value.push(makeLibrary({ id: 4, name: 'Comics', folders: [{ id: 40, path: '/comics', role: 'downloads', createdAt: '2026-01-01' }] }))
+    mountDialog()
+    await flushPromises()
+    expect(wrapper.get<HTMLSelectElement>('select').element.value).toBe('3')
+    expect(wrapper.text()).not.toContain('Podcasts')
+    await wrapper.get('select').setValue('4')
+    await applyButton().trigger('click')
+    expect(JSON.parse((api.mock.calls[0]![1] as RequestInit).body as string)).toMatchObject({ targetLibraryId: 4, targetFolderId: 40 })
+  })
+
+  it.each(['empty', 'folderless', 'failed', 'loading'])('does not submit for a %s destination', async (scenario) => {
+    if (scenario === 'empty') libraries.value = []
+    if (scenario === 'folderless') libraries.value[0]!.folders = []
+    if (scenario === 'failed') error.value = 'HTTP 503'
+    if (scenario === 'loading') loading.value = true
+    mountDialog()
+    await flushPromises()
+    expect(applyButton().attributes('disabled')).toBeDefined()
+    await applyButton().trigger('click')
+    expect(api).not.toHaveBeenCalled()
+  })
+
+  it('enables Apply when a delayed library list arrives', async () => {
+    libraries.value = []
+    loaded.value = false
+    mountDialog()
+    await flushPromises()
+    expect(applyButton().attributes('disabled')).toBeDefined()
+    libraries.value = [makeLibrary()]
+    loaded.value = true
+    await flushPromises()
+    expect(applyButton().attributes('disabled')).toBeUndefined()
+    expect(wrapper.find('select').exists()).toBe(false)
+  })
+})
diff --git a/client/src/features/library/components/BookDestinationFields.vue b/client/src/features/library/components/BookDestinationFields.vue
new file mode 100644
index 000000000..4f0fe75c2
--- /dev/null
+++ b/client/src/features/library/components/BookDestinationFields.vue
@@ -0,0 +1,77 @@
+<script setup lang="ts">
+import { useI18n } from 'vue-i18n'
+import type { BookDestination } from '../composables/useBookDestination'
+
+const props = defineProps<{
+  destination: BookDestination
+  libraryLabel: string
+  folderLabel: string
+  scoped?: boolean
+}>()
+const emit = defineEmits<{ change: [] }>()
+const { t } = useI18n()
+
+function parseId(event: Event): number | null {
+  const id = Number((event.target as HTMLSelectElement).value)
+  return Number.isSafeInteger(id) && id > 0 ? id : null
+}
+
+function onLibraryChange(event: Event): void {
+  props.destination.selectLibrary(parseId(event))
+  emit('change')
+}
+
+function onFolderChange(event: Event): void {
+  props.destination.selectFolder(parseId(event))
+  emit('change')
+}
+</script>
+
+<template>
+  <div class="space-y-3">
+    <p v-if="destination.error.value" class="text-sm text-destructive" role="alert">{{ t('library.destination.loadFailed') }}</p>
+    <p v-else-if="!destination.available.value" class="text-sm text-muted-foreground" role="status">{{ t('common.loading') }}</p>
+    <p v-else-if="!destination.libraries.value.length" class="text-sm text-muted-foreground" role="status">
+      {{ t('library.destination.noLibraries') }}
+    </p>
+    <template v-else>
+      <label v-if="!scoped && (destination.libraries.value.length > 1 || !destination.selectedLibrary.value)" class="block">
+        <span class="text-xs font-medium text-muted-foreground">{{ libraryLabel }}</span>
+        <select
+          class="mt-1 w-full h-9 rounded-lg border border-input bg-background px-3 text-sm text-foreground outline-none focus:ring-1 focus:ring-ring"
+          :value="destination.selectedLibrary.value ? destination.libraryId.value : ''"
+          @change="onLibraryChange"
+        >
+          <option value="" disabled>{{ t('library.upload.selectLibrary') }}</option>
+          <option v-for="library in destination.libraries.value" :key="library.id" :value="library.id">{{ library.name }}</option>
+        </select>
+      </label>
+      <dl v-else-if="destination.selectedLibrary.value" class="space-y-1">
+        <dt class="text-xs font-medium text-muted-foreground">{{ libraryLabel }}</dt>
+        <dd class="text-sm text-foreground break-words">{{ destination.selectedLibrary.value.name }}</dd>
+      </dl>
+      <p v-else class="text-sm text-destructive" role="alert">{{ t('library.destination.unavailable') }}</p>
+
+      <template v-if="destination.selectedLibrary.value">
+        <p v-if="!destination.folders.value.length" class="text-sm text-muted-foreground" role="status">
+          {{ t('library.destination.noFolders') }}
+        </p>
+        <label v-else-if="destination.folders.value.length > 1 || !destination.selectedFolder.value" class="block">
+          <span class="text-xs font-medium text-muted-foreground">{{ folderLabel }}</span>
+          <select
+            class="mt-1 w-full h-9 rounded-lg border border-input bg-background px-3 text-sm text-foreground outline-none focus:ring-1 focus:ring-ring"
+            :value="destination.selectedFolder.value ? destination.folderId.value : ''"
+            @change="onFolderChange"
+          >
+            <option value="" disabled>{{ t('library.destination.selectFolder') }}</option>
+            <option v-for="folder in destination.folders.value" :key="folder.id" :value="folder.id">{{ folder.path }}</option>
+          </select>
+        </label>
+        <dl v-else class="space-y-1">
+          <dt class="text-xs font-medium text-muted-foreground">{{ folderLabel }}</dt>
+          <dd class="text-sm text-foreground break-all">{{ destination.selectedFolder.value.path }}</dd>
+        </dl>
+      </template>
+    </template>
+  </div>
+</template>
diff --git a/client/src/features/library/components/BookUploadModal.vue b/client/src/features/library/components/BookUploadModal.vue
index ad23f2281..b1a4f23f6 100644
--- a/client/src/features/library/components/BookUploadModal.vue
+++ b/client/src/features/library/components/BookUploadModal.vue
@@ -1,14 +1,13 @@
 <script setup lang="ts">
-import { computed, onMounted, onUnmounted, ref, watch } from 'vue'
+import { computed, onMounted, onUnmounted, ref } from 'vue'
 import { useRouter } from 'vue-router'
 import { useI18n } from 'vue-i18n'
 import { CheckCircle2, FileUp, Loader2, Plus, RotateCcw, Upload, X, XCircle } from '@lucide/vue'
-import type { Library } from '@bookorbit/types'
 import { useAppInfo } from '@/features/settings/composables/useAppInfo'
 import { SUPPORTED_FORMATS, SUPPORTED_FORMATS_ACCEPT, useBookUpload, type FileUploadStatus } from '../composables/useBookUpload'
 import { emitLibraryUploadCompleted } from '../composables/useLibraryUploadEvents'
-import { useLibraries } from '../composables/useLibraries'
-import { api } from '@/lib/api'
+import { useBookDestination } from '../composables/useBookDestination'
+import BookDestinationFields from './BookDestinationFields.vue'
 import { formatBytes } from '@/lib/formatting'
 const props = defineProps<{
   libraryId?: number
@@ -21,20 +20,17 @@ const emit = defineEmits<{
 
 const router = useRouter()
 const { t } = useI18n()
-const { libraries, fetchLibraries } = useLibraries()
+const destination = useBookDestination({ libraryId: props.libraryId })
+const { libraryId: selectedLibraryId, folderId: selectedFolderId, selectedLibrary, hasDestination, fetchLibraries } = destination
 const { maxUploadSizeMb } = useAppInfo()
 
-const selectedLibraryId = ref<number | undefined>(props.libraryId)
-const folders = ref<Library['folders']>([])
-const selectedFolderId = ref<number | undefined>(undefined)
-const libraryName = ref<string | null>(null)
 const isDragging = ref(false)
 const fileInputRef = ref<HTMLInputElement | null>(null)
 
 const { files, pendingCount, isUploading, doneCount, errorCount, uploadedBookIds, addFiles, removeFile, retryFile, reset, startUpload } =
   useBookUpload()
 
-const canUpload = computed(() => pendingCount.value > 0 && !isUploading.value && selectedLibraryId.value !== undefined)
+const canUpload = computed(() => pendingCount.value > 0 && !isUploading.value && hasDestination.value)
 const hasFiles = computed(() => files.value.length > 0)
 const allDone = computed(() => hasFiles.value && files.value.every((f) => f.status === 'done' || f.status === 'error'))
 const allSuccess = computed(() => allDone.value && errorCount.value === 0)
@@ -42,7 +38,7 @@ const allSuccess = computed(() => allDone.value && errorCount.value === 0)
 const headerTitle = computed(() => {
   if (isUploading.value) return t('library.upload.header.uploading')
   if (allDone.value) return t('library.upload.header.complete')
-  if (libraryName.value) return t('library.upload.header.uploadTo', { library: libraryName.value })
+  if (selectedLibrary.value) return t('library.upload.header.uploadTo', { library: selectedLibrary.value.name })
   return t('library.upload.header.uploadBooks')
 })
 
@@ -58,34 +54,12 @@ const fileSummary = computed(() => {
   return { total: files.value.length, totalBytes, formatParts }
 })
 
-async function loadFolders(libraryId: number) {
-  const res = await api(`/api/v1/libraries/${libraryId}`)
-  if (res.ok) {
-    const data: Library = await res.json()
-    folders.value = data.folders ?? []
-    selectedFolderId.value = folders.value[0]?.id
-    libraryName.value = data.name
-  }
-}
-
-watch(selectedLibraryId, (id) => {
-  folders.value = []
-  selectedFolderId.value = undefined
-  libraryName.value = null
-  if (id !== undefined) loadFolders(id)
-})
-
 function onKeydown(e: KeyboardEvent) {
   if (e.key === 'Escape') handleClose()
 }
 
-onMounted(async () => {
-  if (!props.libraryId) {
-    if (!libraries.value.length) await fetchLibraries()
-    if (selectedLibraryId.value !== undefined) loadFolders(selectedLibraryId.value)
-  } else {
-    loadFolders(props.libraryId)
-  }
+onMounted(() => {
+  void fetchLibraries()
   document.addEventListener('keydown', onKeydown)
 })
 onUnmounted(() => document.removeEventListener('keydown', onKeydown))
@@ -131,8 +105,8 @@ function onFileInputChange(e: Event) {
 
 async function handleUpload() {
   const libraryId = selectedLibraryId.value
-  if (libraryId === undefined) return
-  const folderId = selectedFolderId.value
+  if (!hasDestination.value || libraryId === null) return
+  const folderId = selectedFolderId.value ?? undefined
 
   const pendingAtStart = files.value.filter((f) => f.status === 'pending').length
   if (pendingAtStart === 0) return
@@ -211,28 +185,12 @@ function formatPillClass(filename: string): string {
         </div>
 
         <div class="flex-1 overflow-y-auto p-5 flex flex-col gap-4">
-          <!-- Library selector (only when not pre-scoped to a library) -->
-          <div v-if="!libraryId" class="flex flex-col gap-1.5">
-            <label class="text-xs font-medium text-muted-foreground">{{ t('library.upload.library') }}</label>
-            <select
-              v-model="selectedLibraryId"
-              class="h-8 rounded-md border border-input bg-background px-2.5 text-sm text-foreground focus:outline-none focus:ring-1 focus:ring-ring"
-            >
-              <option :value="undefined" disabled>{{ t('library.upload.selectLibrary') }}</option>
-              <option v-for="lib in libraries" :key="lib.id" :value="lib.id">{{ lib.name }}</option>
-            </select>
-          </div>
-
-          <!-- Folder selector (only shown when library has multiple folders) -->
-          <div v-if="folders.length > 1" class="flex flex-col gap-1.5">
-            <label class="text-xs font-medium text-muted-foreground">{{ t('library.upload.targetFolder') }}</label>
-            <select
-              v-model="selectedFolderId"
-              class="h-8 rounded-md border border-input bg-background px-2.5 text-sm text-foreground focus:outline-none focus:ring-1 focus:ring-ring"
-            >
-              <option v-for="folder in folders" :key="folder.id" :value="folder.id">{{ folder.path }}</option>
-            </select>
-          </div>
+          <BookDestinationFields
+            :destination="destination"
+            :library-label="t('library.upload.library')"
+            :folder-label="t('library.upload.targetFolder')"
+            :scoped="libraryId !== undefined"
+          />
 
           <!-- Shared file input -->
           <input ref="fileInputRef" type="file" multiple :accept="SUPPORTED_FORMATS_ACCEPT" class="sr-only" @change="onFileInputChange" />
diff --git a/client/src/features/library/components/__tests__/BookDestinationFields.spec.ts b/client/src/features/library/components/__tests__/BookDestinationFields.spec.ts
new file mode 100644
index 000000000..8a2207b96
--- /dev/null
+++ b/client/src/features/library/components/__tests__/BookDestinationFields.spec.ts
@@ -0,0 +1,113 @@
+import { mount, type VueWrapper } from '@vue/test-utils'
+import { defineComponent, h, nextTick, ref } from 'vue'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { Library } from '@bookorbit/types'
+import { i18n } from '@/i18n'
+import BookDestinationFields from '../BookDestinationFields.vue'
+import { useBookDestination } from '../../composables/useBookDestination'
+import { makeLibrary } from '../../test/fixtures'
+
+const libraries = ref<Library[]>([])
+const loaded = ref(true)
+const loading = ref(false)
+const error = ref<string | null>(null)
+vi.mock('../../composables/useLibraries', () => ({
+  useLibraries: () => ({
+    libraries,
+    loaded,
+    loading,
+    error,
+    fetchLibraries: vi.fn<() => Promise<void>>(),
+    refreshLibraries: vi.fn<() => Promise<void>>(),
+  }),
+}))
+let wrapper: VueWrapper
+function mountFields(options: Parameters<typeof useBookDestination>[0] = {}, scoped = false) {
+  wrapper = mount(
+    defineComponent({
+      setup() {
+        const destination = useBookDestination(options)
+        return () => h(BookDestinationFields, { destination, libraryLabel: 'Library', folderLabel: 'Folder', scoped })
+      },
+    }),
+  )
+  return wrapper.getComponent(BookDestinationFields)
+}
+
+beforeEach(() => {
+  i18n.global.locale.value = 'en'
+  libraries.value = [makeLibrary()]
+  loaded.value = true
+  loading.value = false
+  error.value = null
+})
+afterEach(() => wrapper?.unmount())
+
+describe('BookDestinationFields', () => {
+  it('renders the sole library and folder as readable text without selects', () => {
+    mountFields()
+    expect(wrapper.findAll('select')).toHaveLength(0)
+    expect(wrapper.findAll('dt').map((term) => term.text())).toEqual(['Library', 'Folder'])
+    expect(wrapper.findAll('dd').map((value) => value.text())).toEqual(['Main Library', '/books'])
+  })
+
+  it('offers a programmatically labelled folder selector when only folders require a choice', async () => {
+    libraries.value[0]!.folders.push({ ...libraries.value[0]!.folders[0]!, id: 31, path: '/books/second' })
+    const fields = mountFields()
+    const label = wrapper.get('label')
+    expect(label.text()).toContain('Folder')
+    expect(wrapper.findAll('select')).toHaveLength(1)
+    await label.get('select').setValue('31')
+    expect(fields.props('destination').folderId.value).toBe(31)
+    expect(fields.emitted('change')).toEqual([[]])
+  })
+
+  it('offers a library selector and keeps a scoped library read-only', async () => {
+    libraries.value.push(makeLibrary({ id: 4, name: 'Comics' }))
+    const fields = mountFields()
+    expect(wrapper.get('label').text()).toContain('Library')
+    await wrapper.get('select').setValue('4')
+    expect(fields.props('destination').libraryId.value).toBe(4)
+    expect(wrapper.get('dd').text()).toBe('/books')
+    wrapper.unmount()
+    mountFields({ libraryId: 4 }, true)
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).toContain('Comics')
+  })
+
+  it('exposes loading, failure, and empty states accessibly', async () => {
+    loaded.value = false
+    mountFields()
+    expect(wrapper.get('[role="status"]').text()).toBe('Loading...')
+    error.value = 'HTTP 503'
+    await nextTick()
+    expect(wrapper.get('[role="alert"]').text()).toContain('Could not load')
+    expect(wrapper.text()).not.toContain('HTTP 503')
+    error.value = null
+    loaded.value = true
+    libraries.value = []
+    await nextTick()
+    expect(wrapper.get('[role="status"]').text()).toContain('No book libraries')
+  })
+
+  it('explains a missing folder without showing an empty dropdown', () => {
+    libraries.value = [makeLibrary({ folders: [] })]
+    mountFields()
+    expect(wrapper.get('[role="status"]').text()).toContain('no destination folders')
+    expect(wrapper.find('select').exists()).toBe(false)
+  })
+
+  it('allows an unavailable carried destination to be corrected even with one choice', async () => {
+    const fields = mountFields({ libraryId: 99, folderId: 99 })
+    expect(wrapper.get<HTMLSelectElement>('select').element.value).toBe('')
+    await wrapper.get('select').setValue('3')
+    expect(fields.props('destination').hasDestination.value).toBe(true)
+    expect(wrapper.find('select').exists()).toBe(false)
+  })
+
+  it('shows an unavailable scoped library without silently replacing it', () => {
+    mountFields({ libraryId: 99 }, true)
+    expect(wrapper.get('[role="alert"]').text()).toContain('no longer available')
+    expect(wrapper.find('select').exists()).toBe(false)
+  })
+})
diff --git a/client/src/features/library/components/__tests__/BookUploadModal.spec.ts b/client/src/features/library/components/__tests__/BookUploadModal.spec.ts
new file mode 100644
index 000000000..286039629
--- /dev/null
+++ b/client/src/features/library/components/__tests__/BookUploadModal.spec.ts
@@ -0,0 +1,158 @@
+import { flushPromises, mount, type VueWrapper } from '@vue/test-utils'
+import { computed, ref } from 'vue'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { Library } from '@bookorbit/types'
+import { i18n } from '@/i18n'
+import BookUploadModal from '../BookUploadModal.vue'
+import { makeLibrary } from '../../test/fixtures'
+import type { FileUploadItem } from '../../composables/useBookUpload'
+
+const libraries = ref<Library[]>([])
+const loaded = ref(true)
+const loading = ref(false)
+const error = ref<string | null>(null)
+const fetchLibraries = vi.fn<() => Promise<void>>()
+const startUpload = vi.fn<(...args: unknown[]) => Promise<void>>()
+const files = ref<FileUploadItem[]>([])
+vi.mock('../../composables/useLibraries', () => ({
+  useLibraries: () => ({ libraries, loaded, loading, error, fetchLibraries, refreshLibraries: vi.fn<() => Promise<void>>() }),
+}))
+vi.mock('vue-router', () => ({ useRouter: () => ({ push: vi.fn<(to: unknown) => void>() }) }))
+vi.mock('@/features/settings/composables/useAppInfo', () => ({ useAppInfo: () => ({ maxUploadSizeMb: ref(500) }) }))
+vi.mock('../../composables/useLibraryUploadEvents', () => ({ emitLibraryUploadCompleted: vi.fn<(event: unknown) => void>() }))
+vi.mock('../../composables/useBookUpload', () => ({
+  SUPPORTED_FORMATS: ['epub'],
+  SUPPORTED_FORMATS_ACCEPT: '.epub',
+  useBookUpload: () => ({
+    files,
+    pendingCount: computed(() => files.value.filter((file) => file.status === 'pending').length),
+    isUploading: ref(false),
+    doneCount: ref(0),
+    errorCount: ref(0),
+    uploadedBookIds: ref([]),
+    addFiles: vi.fn<(files: File[]) => void>(),
+    removeFile: vi.fn<(id: string) => void>(),
+    retryFile: vi.fn<(id: string) => void>(),
+    reset: vi.fn<() => void>(),
+    startUpload,
+  }),
+}))
+let wrapper: VueWrapper
+function mountUpload(libraryId?: number) {
+  wrapper = mount(BookUploadModal, { props: { libraryId }, global: { stubs: { Teleport: true } } })
+  return wrapper
+}
+function uploadButton() {
+  return wrapper.findAll('button').find((button) => button.text().startsWith('Upload ('))!
+}
+
+beforeEach(() => {
+  i18n.global.locale.value = 'en'
+  libraries.value = [makeLibrary()]
+  loaded.value = true
+  loading.value = false
+  error.value = null
+  fetchLibraries.mockReset().mockResolvedValue(undefined)
+  startUpload.mockReset().mockResolvedValue(undefined)
+  files.value = [{ id: 'book', file: new File(['book'], 'book.epub'), status: 'pending', progress: 0 }]
+})
+afterEach(() => wrapper?.unmount())
+
+describe('BookUploadModal destination', () => {
+  it('enables upload to the sole library without any selection and sends its folder', async () => {
+    mountUpload()
+    await flushPromises()
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).toContain('Upload to Main Library')
+    expect(uploadButton().attributes('disabled')).toBeUndefined()
+    expect(startUpload).not.toHaveBeenCalled()
+    await uploadButton().trigger('click')
+    expect(startUpload).toHaveBeenCalledExactlyOnceWith(3, 30)
+  })
+
+  it('waits for a delayed successful library load before enabling upload', async () => {
+    libraries.value = []
+    loaded.value = false
+    loading.value = true
+    let finish!: () => void
+    fetchLibraries.mockImplementation(
+      () =>
+        new Promise<void>((resolve) => {
+          finish = resolve
+        }),
+    )
+    mountUpload()
+    expect(uploadButton().attributes('disabled')).toBeDefined()
+    libraries.value = [makeLibrary()]
+    loaded.value = true
+    loading.value = false
+    finish()
+    await flushPromises()
+    expect(uploadButton().attributes('disabled')).toBeUndefined()
+    expect(wrapper.find('select').exists()).toBe(false)
+  })
+
+  it('requires a choice with multiple libraries and resets the folder when changing library', async () => {
+    libraries.value.push(makeLibrary({ id: 4, name: 'Comics', folders: [{ id: 40, path: '/comics', role: 'downloads', createdAt: '2026-01-01' }] }))
+    mountUpload()
+    await flushPromises()
+    expect(uploadButton().attributes('disabled')).toBeDefined()
+    await wrapper.get('select').setValue('4')
+    expect(wrapper.text()).toContain('Upload to Comics')
+    await uploadButton().trigger('click')
+    expect(startUpload).toHaveBeenLastCalledWith(4, 40)
+    await wrapper.get('select').setValue('3')
+    await uploadButton().trigger('click')
+    expect(startUpload).toHaveBeenLastCalledWith(3, 30)
+  })
+
+  it('keeps multiple folders selectable in a sole library', async () => {
+    libraries.value[0]!.folders.push({ ...libraries.value[0]!.folders[0]!, id: 31, path: '/books/second' })
+    mountUpload()
+    await flushPromises()
+    expect(wrapper.findAll('select')).toHaveLength(1)
+    await wrapper.get('select').setValue('31')
+    await uploadButton().trigger('click')
+    expect(startUpload).toHaveBeenCalledExactlyOnceWith(3, 31)
+  })
+
+  it('preserves a caller-scoped library even when it is not first', async () => {
+    libraries.value.push(makeLibrary({ id: 4, name: 'Comics' }))
+    mountUpload(4)
+    await flushPromises()
+    expect(wrapper.find('select').exists()).toBe(false)
+    expect(wrapper.text()).toContain('Comics')
+    await uploadButton().trigger('click')
+    expect(startUpload).toHaveBeenCalledExactlyOnceWith(4, 30)
+  })
+
+  it('excludes podcast libraries from the sole-library calculation', async () => {
+    libraries.value.unshift(makeLibrary({ id: 1, type: 'podcasts', name: 'Podcasts' }))
+    mountUpload()
+    await flushPromises()
+    expect(wrapper.text()).not.toContain('Podcasts')
+    await uploadButton().trigger('click')
+    expect(startUpload).toHaveBeenCalledExactlyOnceWith(3, 30)
+  })
+
+  it.each(['empty', 'folderless', 'failed', 'unavailable'])('keeps upload disabled for a %s destination', async (scenario) => {
+    if (scenario === 'empty') libraries.value = []
+    if (scenario === 'folderless') libraries.value = [makeLibrary({ folders: [] })]
+    if (scenario === 'failed') error.value = 'HTTP 503'
+    mountUpload(scenario === 'unavailable' ? 99 : undefined)
+    await flushPromises()
+    expect(uploadButton().attributes('disabled')).toBeDefined()
+    await uploadButton().trigger('click')
+    expect(startUpload).not.toHaveBeenCalled()
+    expect(wrapper.find('[role="status"], [role="alert"]').exists()).toBe(true)
+  })
+
+  it('disables upload if the selected folder is removed during a refresh', async () => {
+    mountUpload()
+    await flushPromises()
+    libraries.value = [makeLibrary({ folders: [] })]
+    await flushPromises()
+    expect(uploadButton().attributes('disabled')).toBeDefined()
+    expect(startUpload).not.toHaveBeenCalled()
+  })
+})
diff --git a/client/src/features/library/composables/__tests__/useBookDestination.spec.ts b/client/src/features/library/composables/__tests__/useBookDestination.spec.ts
new file mode 100644
index 000000000..17f426bc1
--- /dev/null
+++ b/client/src/features/library/composables/__tests__/useBookDestination.spec.ts
@@ -0,0 +1,217 @@
+import { effectScope, nextTick, ref } from 'vue'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { useBookDestination } from '../useBookDestination'
+import { makeLibrary } from '../../test/fixtures'
+import type { Library } from '@bookorbit/types'
+
+const libraries = ref<Library[]>([])
+const loaded = ref(false)
+const loading = ref(false)
+const error = ref<string | null>(null)
+const fetchLibraries = vi.fn<() => Promise<void>>()
+const refreshLibraries = vi.fn<() => Promise<void>>()
+vi.mock('../useLibraries', () => ({
+  useLibraries: () => ({
+    libraries,
+    loaded,
+    loading,
+    error,
+    fetchLibraries,
+    refreshLibraries,
+  }),
+}))
+let scope = effectScope()
+function destination(options: Parameters<typeof useBookDestination>[0] = {}) {
+  return scope.run(() => useBookDestination(options))!
+}
+
+beforeEach(() => {
+  scope = effectScope()
+  libraries.value = []
+  loaded.value = false
+  loading.value = false
+  error.value = null
+  fetchLibraries.mockReset().mockResolvedValue(undefined)
+  refreshLibraries.mockReset().mockResolvedValue(undefined)
+})
+afterEach(() => scope.stop())
+
+function load(items: Library[]) {
+  libraries.value = items
+  loaded.value = true
+}
+
+describe('useBookDestination', () => {
+  it('selects the sole book library and its folder after the list finishes loading', async () => {
+    const state = destination()
+    libraries.value = [makeLibrary()]
+    loading.value = true
+    await nextTick()
+    expect(state.libraryId.value).toBeNull()
+    expect(state.hasDestination.value).toBe(false)
+    loaded.value = true
+    loading.value = false
+    await nextTick()
+    expect(state.libraryId.value).toBe(3)
+    expect(state.folderId.value).toBe(30)
+    expect(state.hasDestination.value).toBe(true)
+  })
+
+  it('uses a cached list immediately and excludes podcast libraries', () => {
+    load([makeLibrary({ id: 1, type: 'podcasts' }), makeLibrary()])
+    const state = destination()
+    expect(state.libraries.value.map((library) => library.id)).toEqual([3])
+    expect(state.libraryId.value).toBe(3)
+    expect(state.hasDestination.value).toBe(true)
+  })
+
+  it('requires a choice when there are multiple libraries', () => {
+    load([makeLibrary({ id: 1 }), makeLibrary()])
+    const state = destination()
+    expect(state.libraryId.value).toBeNull()
+    expect(state.folderId.value).toBeNull()
+    expect(state.hasDestination.value).toBe(false)
+  })
+
+  it('preserves the existing Dock first-library default when requested', () => {
+    load([makeLibrary({ id: 1 }), makeLibrary()])
+    const state = destination({ defaultToFirstLibrary: true })
+    expect(state.libraryId.value).toBe(1)
+    expect(state.folderId.value).toBe(30)
+  })
+
+  it.each([[], [makeLibrary({ type: 'podcasts' })], [makeLibrary({ folders: [] })]].map((items) => ({ items })))(
+    'does not report a destination for an empty library or folder list',
+    ({ items }) => {
+      load(items)
+      expect(destination().hasDestination.value).toBe(false)
+    },
+  )
+
+  it('preserves a carried library and non-first folder across loading and refreshes', async () => {
+    const state = destination({ libraryId: 3, folderId: 31 })
+    const library = makeLibrary()
+    library.folders.push({ ...library.folders[0]!, id: 31, path: '/books/second' })
+    load([makeLibrary({ id: 1 }), library])
+    await nextTick()
+    expect(state.libraryId.value).toBe(3)
+    expect(state.folderId.value).toBe(31)
+    libraries.value = [library, makeLibrary({ id: 1 })]
+    await nextTick()
+    expect(state.folderId.value).toBe(31)
+    expect(state.hasDestination.value).toBe(true)
+  })
+
+  it('fills a missing folder in the carried library', () => {
+    load([makeLibrary({ id: 1 }), makeLibrary()])
+    const state = destination({ libraryId: 3 })
+    expect(state.libraryId.value).toBe(3)
+    expect(state.folderId.value).toBe(30)
+  })
+
+  it('changes folders with the selected library and keeps manual selections after refresh', async () => {
+    const second = makeLibrary({ id: 4, folders: [{ id: 40, path: '/comics', role: 'downloads', createdAt: '2026-01-01' }] })
+    second.folders.push({ ...second.folders[0]!, id: 41 })
+    load([makeLibrary(), second])
+    const state = destination()
+    state.selectLibrary(4)
+    state.selectFolder(41)
+    await nextTick()
+    expect(state.hasDestination.value).toBe(true)
+    libraries.value = [makeLibrary(), second]
+    await nextTick()
+    expect(state.libraryId.value).toBe(4)
+    expect(state.folderId.value).toBe(41)
+    state.selectLibrary(3)
+    expect(state.folderId.value).toBe(30)
+  })
+
+  it('clears the previous folder when a library has no folders', async () => {
+    load([makeLibrary(), makeLibrary({ id: 4, folders: [] })])
+    const state = destination({ libraryId: 3 })
+    state.selectLibrary(4)
+    await nextTick()
+    expect(state.folderId.value).toBeNull()
+    expect(state.hasDestination.value).toBe(false)
+  })
+
+  it.each([
+    { libraryId: 99, folderId: 30 },
+    { libraryId: 3, folderId: 99 },
+  ])('preserves unavailable carried IDs without treating them as valid', (carried) => {
+    load([makeLibrary()])
+    const state = destination(carried)
+    expect(state.libraryId.value).toBe(carried.libraryId)
+    expect(state.folderId.value).toBe(carried.folderId)
+    expect(state.hasDestination.value).toBe(false)
+  })
+
+  it('invalidates a destination when its library or folder disappears', async () => {
+    load([makeLibrary()])
+    const state = destination()
+    libraries.value = [makeLibrary({ folders: [] })]
+    await nextTick()
+    expect(state.hasDestination.value).toBe(false)
+    expect(state.folderId.value).toBe(30)
+    libraries.value = []
+    await nextTick()
+    expect(state.hasDestination.value).toBe(false)
+    expect(state.libraryId.value).toBe(3)
+  })
+
+  it('blocks cached destinations while refreshing or after a failed request', async () => {
+    load([makeLibrary()])
+    const state = destination()
+    loading.value = true
+    await nextTick()
+    expect(state.hasDestination.value).toBe(false)
+    loading.value = false
+    error.value = 'HTTP 503'
+    await nextTick()
+    expect(state.hasDestination.value).toBe(false)
+    error.value = null
+    await nextTick()
+    expect(state.hasDestination.value).toBe(true)
+  })
+
+  it('does not infer a default from a failed load', () => {
+    load([makeLibrary()])
+    error.value = 'HTTP 503'
+    const state = destination()
+    expect(state.libraryId.value).toBeNull()
+    expect(state.folderId.value).toBeNull()
+  })
+
+  it('resets both carried IDs when switching Dock files', async () => {
+    load([makeLibrary(), makeLibrary({ id: 4, folders: [{ id: 40, path: '/comics', role: 'downloads', createdAt: '2026-01-01' }] })])
+    const state = destination({ defaultToFirstLibrary: true })
+    state.reset(4, 40)
+    await nextTick()
+    expect(state.libraryId.value).toBe(4)
+    expect(state.folderId.value).toBe(40)
+    state.reset(null, null)
+    await nextTick()
+    expect(state.libraryId.value).toBe(3)
+    expect(state.folderId.value).toBe(30)
+  })
+  it('uses the normal cached fetch when no previous request failed', async () => {
+    const state = destination()
+    await state.fetchLibraries()
+    expect(fetchLibraries).toHaveBeenCalledExactlyOnceWith()
+    expect(refreshLibraries).not.toHaveBeenCalled()
+  })
+
+  it('retries a failed refresh even when a library list was already cached', async () => {
+    load([makeLibrary()])
+    error.value = 'HTTP 503'
+    const state = destination()
+    refreshLibraries.mockImplementation(async () => {
+      error.value = null
+    })
+    await state.fetchLibraries()
+    await nextTick()
+    expect(refreshLibraries).toHaveBeenCalledExactlyOnceWith()
+    expect(fetchLibraries).not.toHaveBeenCalled()
+    expect(state.hasDestination.value).toBe(true)
+  })
+})
diff --git a/client/src/features/library/composables/useBookDestination.ts b/client/src/features/library/composables/useBookDestination.ts
new file mode 100644
index 000000000..f6fca8fbc
--- /dev/null
+++ b/client/src/features/library/composables/useBookDestination.ts
@@ -0,0 +1,68 @@
+import { computed, ref, watchEffect } from 'vue'
+import { useLibraries } from './useLibraries'
+
+interface BookDestinationOptions {
+  libraryId?: number | null
+  folderId?: number | null
+  defaultToFirstLibrary?: boolean
+}
+
+export function useBookDestination(options: BookDestinationOptions = {}) {
+  const source = useLibraries()
+  const libraries = computed(() => source.libraries.value.filter((library) => library.type === 'books'))
+  const libraryId = ref<number | null>(options.libraryId ?? null)
+  const folderId = ref<number | null>(options.folderId ?? null)
+  const selectedLibrary = computed(() => libraries.value.find((library) => library.id === libraryId.value))
+  const folders = computed(() => selectedLibrary.value?.folders ?? [])
+  const selectedFolder = computed(() => folders.value.find((folder) => folder.id === folderId.value))
+  const available = computed(() => source.loaded.value && !source.loading.value && !source.error.value)
+  const hasDestination = computed(() => available.value && !!selectedLibrary.value && !!selectedFolder.value)
+
+  watchEffect(() => {
+    if (!available.value) return
+    if (libraryId.value === null && (libraries.value.length === 1 || options.defaultToFirstLibrary)) {
+      libraryId.value = libraries.value[0]?.id ?? null
+    }
+    if (folderId.value === null) folderId.value = folders.value[0]?.id ?? null
+  })
+
+  async function fetchLibraries(): Promise<void> {
+    if (source.error.value) await source.refreshLibraries()
+    else await source.fetchLibraries()
+  }
+
+  function selectLibrary(id: number | null): void {
+    libraryId.value = id
+    folderId.value = libraries.value.find((library) => library.id === id)?.folders[0]?.id ?? null
+  }
+
+  function selectFolder(id: number | null): void {
+    folderId.value = id
+  }
+
+  function reset(library: number | null, folder: number | null): void {
+    libraryId.value = library
+    folderId.value = folder
+  }
+
+  return {
+    libraries,
+    libraryId,
+    folderId,
+    selectedLibrary,
+    folders,
+    selectedFolder,
+    available,
+    hasDestination,
+    loading: source.loading,
+    loaded: source.loaded,
+    error: source.error,
+    fetchLibraries,
+    refreshLibraries: source.refreshLibraries,
+    selectLibrary,
+    selectFolder,
+    reset,
+  }
+}
+
+export type BookDestination = ReturnType<typeof useBookDestination>
diff --git a/client/src/features/library/test/fixtures.ts b/client/src/features/library/test/fixtures.ts
new file mode 100644
index 000000000..ff74b3d2e
--- /dev/null
+++ b/client/src/features/library/test/fixtures.ts
@@ -0,0 +1,42 @@
+import type { Library } from '@bookorbit/types'
+
+export function makeLibrary(overrides: Partial<Library> = {}): Library {
+  return {
+    id: 3,
+    type: 'books',
+    name: 'Main Library',
+    icon: null,
+    displayOrder: 0,
+    coverAspectRatio: '2/3',
+    watch: false,
+    autoScanCronExpression: null,
+    metadataPrecedence: [],
+    formatPriority: [],
+    allowedFormats: [],
+    organizationMode: 'book_per_file',
+    addedAtSource: 'imported',
+    excludePatterns: [],
+    readingThreshold: 10,
+    markAsFinishedPercentComplete: 95,
+    fileNamingPattern: null,
+    fileWriteEnabled: false,
+    fileWriteWriteCover: false,
+    fileWriteEpubEnabled: false,
+    fileWriteEpubMaxFileSizeMb: 50,
+    fileWriteFb2Enabled: false,
+    fileWriteFb2MaxFileSizeMb: 100,
+    fileWritePdfEnabled: false,
+    fileWritePdfMaxFileSizeMb: 50,
+    fileWriteCbxEnabled: false,
+    fileWriteCbxMaxFileSizeMb: 50,
+    fileWriteKindleEnabled: false,
+    fileWriteKindleMaxFileSizeMb: 100,
+    fileWriteAudioEnabled: false,
+    fileWriteAudioMaxFileSizeMb: 50,
+    fileRenameEnabled: false,
+    folders: [{ id: 30, path: '/books', role: 'downloads', createdAt: '2026-01-01T00:00:00.000Z' }],
+    createdAt: '2026-01-01T00:00:00.000Z',
+    updatedAt: '2026-01-01T00:00:00.000Z',
+    ...overrides,
+  }
+}
diff --git a/client/src/locales/en.json b/client/src/locales/en.json
index 1cf62dd89..df88968e5 100644
--- a/client/src/locales/en.json
+++ b/client/src/locales/en.json
@@ -9259,6 +9259,13 @@
         "createFolder": "Could not create folder"
       }
     },
+    "destination": {
+      "loadFailed": "Could not load destination libraries. Close and reopen to try again.",
+      "noLibraries": "No book libraries are available. Create a library or ask an administrator for access.",
+      "noFolders": "This library has no destination folders. Add a folder in Library settings.",
+      "unavailable": "The selected library is no longer available.",
+      "selectFolder": "Select a folder..."
+    },
     "upload": {
       "library": "Library",
       "selectLibrary": "Select a library...",