test(bulk-edit): plug Sara's identified coverage gaps

- DocumentServiceTest.applyBulkEditToDocument_propagatesDomainException_whenSenderIdUnresolvable (Sara C1)
- DocumentServiceTest.findIdsForFilter_passesTagOperatorOR_throughBuildSearchSpec (Sara C3)
- bulkSelection.svelte.spec.ts: setAll([]) no-op + previous-IDs-absent + ids getter (Sara C4 + S4)
- /documents/bulk-edit/+page.server.ts now defensively handles a UserGroup
  with NULL `permissions` (treats it as not-WRITE_ALL instead of throwing
  on .includes()) + matching test (Sara C7)

233 backend tests + frontend bulk-edit specs all green.

Refs #225, PR #331

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

frontend/src/lib/stores/bulkSelection.svelte.spec.ts

@@ -50,4 +50,27 @@ describe('bulkSelectionStore', () => {
 		bulkSelectionStore.clear();
 		expect(bulkSelectionStore.size).toBe(0);
 	});
+
+	it('setAll([]) leaves the store empty (no-op when filter returned zero matches)', () => {
+		bulkSelectionStore.add('a');
+		bulkSelectionStore.setAll([]);
+		expect(bulkSelectionStore.size).toBe(0);
+	});
+
+	it('setAll drops all previously selected ids, not just some', () => {
+		bulkSelectionStore.add('a');
+		bulkSelectionStore.add('b');
+		bulkSelectionStore.setAll(['c', 'd']);
+		expect(bulkSelectionStore.has('a')).toBe(false);
+		expect(bulkSelectionStore.has('b')).toBe(false);
+		expect(bulkSelectionStore.has('c')).toBe(true);
+		expect(bulkSelectionStore.has('d')).toBe(true);
+	});
+
+	it('ids getter exposes the current SvelteSet', () => {
+		bulkSelectionStore.add('a');
+		bulkSelectionStore.add('b');
+		const ids = Array.from(bulkSelectionStore.ids);
+		expect(ids.sort()).toEqual(['a', 'b']);
+	});
 });

frontend/src/routes/documents/bulk-edit/+page.server.ts

@@ -1,9 +1,11 @@
 import { redirect } from '@sveltejs/kit';
 
 export async function load({ locals }: { locals: App.Locals }) {
+	// Defensive: a UserGroup row with NULL permissions returns undefined here
+	// rather than throwing on .includes() — treat that as "not WRITE_ALL".
 	const canWrite =
-		locals.user?.groups?.some((g: { permissions: string[] }) =>
-			g.permissions.includes('WRITE_ALL')
+		locals.user?.groups?.some(
+			(g: { permissions?: string[] }) => g.permissions?.includes('WRITE_ALL') ?? false
 		) ?? false;
 	if (!canWrite) throw redirect(303, '/documents');
 	return { canWrite };

frontend/src/routes/documents/bulk-edit/page.server.spec.ts

@@ -43,4 +43,19 @@ describe('/documents/bulk-edit +page.server.ts', () => {
 		const result = await load({ locals });
 		expect(result).toEqual({ canWrite: true });
 	});
+
+	it('redirects when a group has no permissions array (defensive)', async () => {
+		// Sara C7 — a UserGroup row with NULL permissions used to throw on
+		// .includes(); the guard now treats that case as "not WRITE_ALL".
+		const locals = {
+			user: { groups: [{ permissions: undefined as unknown as string[] }] }
+		};
+		try {
+			// @ts-expect-error — partial event shape sufficient for this guard
+			await load({ locals });
+			throw new Error('expected redirect');
+		} catch (e) {
+			expect((e as { status?: number }).status).toBe(303);
+		}
+	});
 });