fix(bulk-upload): skip navigation when any chunk fails to upload

goto('/documents') fired unconditionally, discarding error chips and
leaving the user with no feedback on which files failed. Now only
navigates when hadErrors is false after all chunks complete.

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

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

@@ -1,11 +1,15 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
+import { goto } from '$app/navigation';
 import { cleanup, render } from 'vitest-browser-svelte';
 import { page, userEvent } from 'vitest/browser';
 import BulkDocumentEditLayout from './BulkDocumentEditLayout.svelte';
 
+vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
+
 afterEach(() => {
 	cleanup();
 	vi.unstubAllGlobals();
+	vi.clearAllMocks();
 });
 
 function makeFile(name: string): File {
@@ -80,9 +84,6 @@ describe('BulkDocumentEditLayout', () => {
 		});
 		vi.stubGlobal('fetch', mockFetch);
 
-		// Also stub goto to prevent navigation errors in test
-		vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
-
 		const { container } = render(BulkDocumentEditLayout, {});
 		const files = Array.from({ length: 12 }, (_, i) => makeFile(`f${i}.pdf`));
 		await addFilesViaInput(container, files);
@@ -103,7 +104,6 @@ describe('BulkDocumentEditLayout', () => {
 			json: async () => ({ errors: [{ filename: 'f0.pdf', code: 'FILE_UPLOAD_FAILED' }] })
 		});
 		vi.stubGlobal('fetch', mockFetch);
-		vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
 
 		const { container } = render(BulkDocumentEditLayout, {});
 		await addFilesViaInput(container, [makeFile('f0.pdf')]);
@@ -140,6 +140,25 @@ describe('BulkDocumentEditLayout', () => {
 		expect(metadataJson).toHaveProperty('tagNames');
 	});
 
+	it('save() does not navigate when chunk returns non-ok response', async () => {
+		const mockFetch = vi.fn().mockResolvedValue({
+			ok: false,
+			json: async () => ({ errors: [{ filename: 'f0.pdf', code: 'FILE_UPLOAD_FAILED' }] })
+		});
+		vi.stubGlobal('fetch', mockFetch);
+
+		const { container } = render(BulkDocumentEditLayout, {});
+		await addFilesViaInput(container, [makeFile('f0.pdf')]);
+
+		const saveBtn = container.querySelector(
+			'button[data-testid="bulk-save-btn"]'
+		) as HTMLButtonElement;
+		saveBtn.click();
+
+		await vi.waitFor(() => expect(mockFetch).toHaveBeenCalledTimes(1), { timeout: 3000 });
+		expect(goto).not.toHaveBeenCalled();
+	});
+
 	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')]);