refactor(api): extract buildSessionsCsv shared by worker + admin exports

apps/api/test/csv.test.ts

@@ -0,0 +1,34 @@
+import { describe, it, expect } from 'vitest';
+import { buildSessionsCsv, type SessionCsvRow } from '../src/lib/csv';
+
+const row: SessionCsvRow = {
+  id: 7,
+  activityName: 'Frezen',
+  userName: 'Jan',
+  insoleType: 'Kurk',
+  pairCount: 2,
+  startTime: new Date('2026-06-17T08:00:00Z'),
+  endTime: new Date('2026-06-17T08:01:30Z'),
+  durationSeconds: 90,
+  pausedSeconds: 0,
+};
+
+describe('buildSessionsCsv', () => {
+  it('omits the Worker column by default (legacy header)', () => {
+    const lines = buildSessionsCsv([row]).split('\n');
+    expect(lines[0]).toBe(
+      '"ID","Task","Insole Type","No. of Insoles","Date","Total Duration","Paused Duration","Start Time","End Time"',
+    );
+    expect(lines[1]).toContain('"Frezen"');
+    expect(lines[1]).toContain('"00:01:30"');
+    expect(lines[1]).not.toContain('"Jan"');
+  });
+
+  it('prepends a Worker column when includeWorker is true', () => {
+    const lines = buildSessionsCsv([row], { includeWorker: true }).split('\n');
+    expect(lines[0]).toBe(
+      '"Worker","ID","Task","Insole Type","No. of Insoles","Date","Total Duration","Paused Duration","Start Time","End Time"',
+    );
+    expect(lines[1].startsWith('"Jan"')).toBe(true);
+  });
+});