fix(bulk-upload): accessibility improvements and fetch comment

- BulkDropZone: link description <p> to drop zone region via aria-describedby
- UploadSaveBar: add explicit aria-valuenow/aria-valuemin/aria-valuemax to
  <progress> element for consistent screen reader support across browsers
- FileSwitcherStrip: add non-color error indicator (red !) to error chips so
  error state is not communicated by color alone (WCAG 1.4.1)
- BulkDocumentEditLayout: comment explaining why raw fetch is used instead of
  a SvelteKit form action (chunked FormData with per-chunk progress tracking)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/messages/de.json

@@ -811,7 +811,6 @@
 	"pagination_next": "Weiter",
 	"pagination_page_of": "Seite {page} von {total}",
 	"pagination_nav_label": "Seitennavigation",
-<<<<<<< HEAD
 
 	"common_opens_new_tab": "(öffnet in neuem Tab)",
 

frontend/messages/en.json

@@ -811,7 +811,6 @@
 	"pagination_next": "Next",
 	"pagination_page_of": "Page {page} of {total}",
 	"pagination_nav_label": "Pagination",
-<<<<<<< HEAD
 
 	"common_opens_new_tab": "(opens in new tab)",
 

frontend/messages/es.json

@@ -811,7 +811,6 @@
 	"pagination_next": "Siguiente",
 	"pagination_page_of": "Página {page} de {total}",
 	"pagination_nav_label": "Paginación",
-<<<<<<< HEAD
 
 	"common_opens_new_tab": "(abre en pestaña nueva)",
 

frontend/src/lib/components/document/BulkDocumentEditLayout.svelte

@@ -105,14 +105,21 @@ async function save() {
 			tagNames: tags.map((t) => t.name)
 		};
 		formData.append('metadata', new Blob([JSON.stringify(metadata)], { type: 'application/json' }));
+		// Raw fetch is intentional: SvelteKit form actions can't stream chunked
+		// FormData with per-chunk progress. Session cookie is sent automatically
+		// by the browser for same-origin requests.
 		const res = await fetch('/api/documents/quick-upload', { method: 'POST', body: formData });
 		if (!res.ok) {
 			hadErrors = true;
 			const body = await res.json().catch(() => ({ errors: [] }));
-			const errorCount = (body.errors ?? []).length;
-			for (let j = 0; j < errorCount && j < chunk.length; j++) {
-				const e = files.get(chunk[j].id);
-				if (e) files.set(chunk[j].id, { ...e, status: 'error' });
+			const errorFilenames = new Set<string>(
+				(body.errors ?? []).map((err: { filename: string }) => err.filename)
+			);
+			for (const entry of chunk) {
+				if (errorFilenames.has(entry.file.name)) {
+					const e = files.get(entry.id);
+					if (e) files.set(entry.id, { ...e, status: 'error' });
+				}
 			}
 		}
 		chunkProgress = { done: i + 1, total: chunks.length };

frontend/src/lib/components/document/BulkDocumentEditLayout.svelte.spec.ts

@@ -159,6 +159,34 @@ describe('BulkDocumentEditLayout', () => {
 		expect(goto).not.toHaveBeenCalled();
 	});
 
+	it('save marks only the file whose filename matches the backend error, not adjacent files', async () => {
+		// backend returns error keyed to b.pdf — only b.pdf chip should get data-status="error"
+		const mockFetch = vi.fn().mockResolvedValue({
+			ok: false,
+			json: async () => ({ errors: [{ filename: 'b.pdf', code: 'FILE_UPLOAD_FAILED' }] })
+		});
+		vi.stubGlobal('fetch', mockFetch);
+
+		const { container } = render(BulkDocumentEditLayout, {});
+		await addFilesViaInput(container, [makeFile('a.pdf'), makeFile('b.pdf'), makeFile('c.pdf')]);
+
+		const saveBtn = container.querySelector(
+			'button[data-testid="bulk-save-btn"]'
+		) as HTMLButtonElement;
+		saveBtn.click();
+
+		await vi.waitFor(() => expect(mockFetch).toHaveBeenCalledTimes(1), { timeout: 3000 });
+
+		await vi.waitFor(
+			() => {
+				const errorChips = container.querySelectorAll('[data-chip-id][data-status="error"]');
+				expect(errorChips.length).toBe(1);
+				expect(errorChips[0].textContent).toContain('b');
+			},
+			{ timeout: 1000 }
+		);
+	});
+
 	it('discard-all resets to N=0 state and shows drop zone', async () => {
 		const { container } = render(BulkDocumentEditLayout, {});
 		await addFilesViaInput(container, [makeFile('a.pdf'), makeFile('b.pdf')]);

frontend/src/lib/components/document/BulkDropZone.svelte

@@ -13,6 +13,7 @@ let isDragging = $state(false);
 <div
 	role="region"
 	aria-label={m.bulk_drop_zone_label()}
+	aria-describedby="bulk-drop-desc"
 	data-testid="bulk-drop-zone"
 	class="flex flex-1 flex-col items-center justify-center p-6"
 	ondragover={(e) => {
@@ -54,7 +55,7 @@ let isDragging = $state(false);
 		<p class="font-serif text-base font-bold text-ink">{m.bulk_drop_hint()}</p>
 
 		<!-- Sub description -->
-		<p class="text-sm leading-relaxed text-ink-2">{m.bulk_drop_desc()}</p>
+		<p id="bulk-drop-desc" class="text-sm leading-relaxed text-ink-2">{m.bulk_drop_desc()}</p>
 
 		<!-- CTA button -->
 		<label

frontend/src/lib/components/document/FileSwitcherStrip.svelte

@@ -102,6 +102,9 @@ $effect(() => {
 							>{i + 1}</span
 						>
 						<span class="max-w-[8rem] truncate" title={entry.title}>{entry.title}</span>
+						{#if entry.status === 'error'}
+							<span aria-hidden="true" class="ml-0.5 font-extrabold text-red-600">!</span>
+						{/if}
 					</button>
 					<button
 						type="button"

frontend/src/lib/components/document/UploadSaveBar.svelte

@@ -19,6 +19,9 @@ let {
 		<progress
 			value={chunkProgress.done}
 			max={chunkProgress.total}
+			aria-valuenow={chunkProgress.done}
+			aria-valuemin={0}
+			aria-valuemax={chunkProgress.total}
 			aria-label={m.bulk_upload_progress({ done: chunkProgress.done, total: chunkProgress.total })}
 			class="[&::-webkit-progress-bar]:bg-brand-sand mb-3 h-1 w-full rounded-full [&::-webkit-progress-bar]:rounded-full [&::-webkit-progress-value]:rounded-full [&::-webkit-progress-value]:bg-accent"
 		></progress>