fix: prevent sheet name too long in excel export

apps/server/src/api-data/excel/__tests__/excel.service.test.ts

@@ -0,0 +1,37 @@
+import xlsx from 'xlsx';
+
+import { demoDb } from '../../../models/demoProject.js';
+import { generateExcelFile } from '../excel.service.js';
+
+describe('generateExcelFile()', () => {
+  it('sanitises long worksheet names to an Excel-compatible value', () => {
+    const buffer = generateExcelFile(
+      {
+        ...demoDb.rundowns.default,
+        title: 'This is a very long name with many characters and weird things: like [Main]/?*',
+      },
+      demoDb.customFields,
+    );
+
+    const workbook = xlsx.read(buffer, { type: 'buffer' });
+    const worksheetName = workbook.SheetNames[0];
+
+    expect(worksheetName).toBeDefined();
+    expect(worksheetName.length).toBeLessThanOrEqual(31);
+    expect(worksheetName).not.toMatch(/[:\\/?*3[\]]/);
+  });
+
+  it('falls back to default worksheet name when title is fully invalid', () => {
+    const buffer = generateExcelFile(
+      {
+        ...demoDb.rundowns.default,
+        title: '[]:*?/\\',
+      },
+      demoDb.customFields,
+    );
+
+    const workbook = xlsx.read(buffer, { type: 'buffer' });
+
+    expect(workbook.SheetNames[0]).toBe('Rundown');
+  });
+});