feat(07-05): DocumentCard classification_failed badge + Re-analyze button + Vitest coverage

- Add red "Classification failed" pill badge when doc.status === 'classification_failed'
- Re-analyze button calls classifyDocument(doc.id) via @click.stop, emits 'reclassified'
- Spinner text "Re-analyzing…" while in flight; resets after 500ms (via setTimeout)
- Existing is_shared badge block preserved unchanged
- Create frontend/tests/DocumentCard.spec.js: 4 Vitest tests covering badge render,
  no-badge for ready/processing, and reanalyze() calling classifyDocument + emit
- 131 frontend tests pass, build exits 0 (D-11 frontend coverage per CLAUDE.md)

frontend/src/components/documents/DocumentCard.vue

@@ -31,6 +31,19 @@
         <div v-if="doc.is_shared" class="mt-2">
           <span class="bg-indigo-50 text-indigo-600 text-xs font-medium px-2 py-1 rounded-full">Shared</span>
         </div>
+
+        <!-- Classification failed badge + Re-analyze button -->
+        <div v-if="doc.status === 'classification_failed'" class="mt-2 flex items-center gap-2">
+          <span class="bg-red-50 text-red-600 text-xs font-medium px-2 py-1 rounded-full">Classification failed</span>
+          <button
+            @click.stop="reanalyze"
+            :disabled="reanalyzing"
+            class="text-xs text-indigo-600 hover:text-indigo-700 font-semibold disabled:opacity-50"
+          >
+            <span v-if="reanalyzing">Re-analyzing…</span>
+            <span v-else>Re-analyze</span>
+          </button>
+        </div>
       </div>
 
       <!-- Action buttons (hover-reveal) -->
@@ -94,7 +107,7 @@
 import { ref, computed, onMounted, onUnmounted } from 'vue'
 import { useTopicsStore } from '../../stores/topics.js'
 import { useFoldersStore } from '../../stores/folders.js'
-import { moveDocument } from '../../api/client.js'
+import { moveDocument, classifyDocument } from '../../api/client.js'
 import TopicBadge from '../topics/TopicBadge.vue'
 import ShareModal from '../sharing/ShareModal.vue'
 import { formatDate, formatSize } from '../../utils/formatters.js'
@@ -103,10 +116,13 @@ const props = defineProps({
   doc: Object,
 })
 
+const emit = defineEmits(['reclassified'])
+
 const topicsStore = useTopicsStore()
 const foldersStore = useFoldersStore()
 const showShareModal = ref(false)
 const showFolderPicker = ref(false)
+const reanalyzing = ref(false)
 
 const allFolders = computed(() => foldersStore.rootFolders)
 
@@ -138,4 +154,16 @@ function topicColor(name) {
   return topicsStore.topics.find(t => t.name === name)?.color ?? '#6366f1'
 }
 
+async function reanalyze() {
+  reanalyzing.value = true
+  try {
+    await classifyDocument(props.doc.id)
+    emit('reclassified', props.doc.id)
+  } catch (e) {
+    console.error('Re-analyze failed:', e.message)
+  } finally {
+    setTimeout(() => { reanalyzing.value = false }, 500)
+  }
+}
+
 </script>

frontend/tests/DocumentCard.spec.js

@@ -0,0 +1,122 @@
+/**
+ * Vitest unit tests for DocumentCard.vue — classification-failed badge
+ * and reanalyze() handler.
+ *
+ * D-11 frontend coverage — CLAUDE.md mandate: every new component / function
+ * must have at least one test.
+ */
+
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { mount, flushPromises } from '@vue/test-utils'
+
+// ── Mock API client ───────────────────────────────────────────────────────────
+vi.mock('../src/api/client.js', () => ({
+  classifyDocument: vi.fn(() =>
+    Promise.resolve({ document_id: 'd1', status: 'processing' })
+  ),
+  // Stub other imports so the component can load without Pinia
+  moveDocument: vi.fn(() => Promise.resolve()),
+}))
+
+// ── Mock Pinia stores referenced by DocumentCard ──────────────────────────────
+vi.mock('../src/stores/topics.js', () => ({
+  useTopicsStore: () => ({ topics: [] }),
+}))
+
+vi.mock('../src/stores/folders.js', () => ({
+  useFoldersStore: () => ({ rootFolders: [] }),
+}))
+
+// ── Mock child components ─────────────────────────────────────────────────────
+vi.mock('../src/components/topics/TopicBadge.vue', () => ({
+  default: { template: '<span></span>' },
+}))
+
+vi.mock('../src/components/sharing/ShareModal.vue', () => ({
+  default: { template: '<div></div>' },
+}))
+
+// ── Mock formatters (used in template) ───────────────────────────────────────
+vi.mock('../src/utils/formatters.js', () => ({
+  formatDate: (v) => String(v),
+  formatSize: (v) => String(v),
+}))
+
+// ── Import component and mock after all mocks are registered ─────────────────
+import DocumentCard from '../src/components/documents/DocumentCard.vue'
+import { classifyDocument } from '../src/api/client.js'
+
+// ── Minimal doc fixture ───────────────────────────────────────────────────────
+function makeDoc(overrides = {}) {
+  return {
+    id: 'd1',
+    original_name: 'test.pdf',
+    size_bytes: 1024,
+    created_at: '2024-01-01T00:00:00Z',
+    topics: [],
+    is_shared: false,
+    status: 'ready',
+    ...overrides,
+  }
+}
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+describe('DocumentCard — classification_failed badge', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('renders Classification failed badge when status === "classification_failed"', () => {
+    const wrapper = mount(DocumentCard, {
+      props: { doc: makeDoc({ status: 'classification_failed' }) },
+      global: { stubs: { RouterLink: true } },
+    })
+
+    expect(wrapper.text()).toContain('Classification failed')
+    const btn = wrapper.find('button[disabled]') || wrapper.findAll('button').find(b => b.text().includes('Re-analyze'))
+    expect(btn || wrapper.text()).toBeTruthy()
+    expect(wrapper.text()).toContain('Re-analyze')
+  })
+
+  it('does NOT render the badge when status is "ready"', () => {
+    const wrapper = mount(DocumentCard, {
+      props: { doc: makeDoc({ status: 'ready' }) },
+      global: { stubs: { RouterLink: true } },
+    })
+
+    expect(wrapper.text()).not.toContain('Classification failed')
+    expect(wrapper.text()).not.toContain('Re-analyze')
+  })
+
+  it('does NOT render the badge when status is "processing"', () => {
+    const wrapper = mount(DocumentCard, {
+      props: { doc: makeDoc({ status: 'processing' }) },
+      global: { stubs: { RouterLink: true } },
+    })
+
+    expect(wrapper.text()).not.toContain('Classification failed')
+  })
+
+  it('Re-analyze button calls classifyDocument(doc.id) and emits "reclassified"', async () => {
+    const wrapper = mount(DocumentCard, {
+      props: { doc: makeDoc({ status: 'classification_failed' }) },
+      global: { stubs: { RouterLink: true } },
+    })
+
+    // Find the Re-analyze button
+    const buttons = wrapper.findAll('button')
+    const reanalyzeBtn = buttons.find(b => b.text().includes('Re-analyze'))
+    expect(reanalyzeBtn).toBeTruthy()
+
+    await reanalyzeBtn.trigger('click')
+    await flushPromises()
+
+    expect(classifyDocument).toHaveBeenCalledOnce()
+    expect(classifyDocument).toHaveBeenCalledWith('d1')
+
+    const emitted = wrapper.emitted('reclassified')
+    expect(emitted).toBeTruthy()
+    expect(emitted[0]).toEqual(['d1'])
+  })
+})