fix(bulk-upload): match error chips by filename, not by chunk position

save() was marking the first N files in a chunk as errored (where N = the
error count returned by the backend), but the backend errors are keyed by
filename. A failure for file[2] would incorrectly mark file[0] as the error.

Now builds a Set of error filenames and matches chunk entries by file.name.
Test added: save marks only the file whose filename matches the backend error.

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

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

@@ -109,10 +109,14 @@ async function save() {
 		if (!res.ok) {
 			hadErrors = true;
 			const body = await res.json().catch(() => ({ errors: [] }));
-			const errorCount = (body.errors ?? []).length;
+			const errorFilenames = new Set<string>(
-			for (let j = 0; j < errorCount && j < chunk.length; j++) {
+				(body.errors ?? []).map((err: { filename: string }) => err.filename)
-				const e = files.get(chunk[j].id);
+			);
-				if (e) files.set(chunk[j].id, { ...e, status: 'error' });
+			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')]);