diff --git a/apps/api/test/csv.test.ts b/apps/api/test/csv.test.ts
index ab2967a..03c32eb 100644
--- a/apps/api/test/csv.test.ts
+++ b/apps/api/test/csv.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest';
-import { buildSessionsCsv, type SessionCsvRow } from '../src/lib/csv';
+import { buildSessionsCsv, quote, formatDuration, type SessionCsvRow } from '../src/lib/csv';
 
 const row: SessionCsvRow = {
   id: 7,
@@ -31,4 +31,52 @@ describe('buildSessionsCsv', () => {
     );
     expect(lines[1].startsWith('"Jan"')).toBe(true);
   });
+
+  it('applies legacy fallbacks for null fields and blanks a missing end time', () => {
+    // Every nullable field null (+ pairCount null via cast, since the type is non-null
+    // but the code still carries a legacy `?? 2` default). includeWorker exercises the
+    // userName fallback too. Covers each `??` fallback branch and the null-end-time branch.
+    const emptyRow = {
+      id: 1,
+      activityName: null,
+      userName: null,
+      insoleType: null,
+      pairCount: null,
+      startTime: new Date('2026-06-17T08:00:00Z'),
+      endTime: null,
+      durationSeconds: null,
+      pausedSeconds: null,
+    } as unknown as SessionCsvRow;
+
+    const cells = buildSessionsCsv([emptyRow], { includeWorker: true }).split('\n')[1].split(',');
+    expect(cells[0]).toBe('""'); // Worker → ''
+    expect(cells[1]).toBe('"1"'); // ID
+    expect(cells[2]).toBe('""'); // Task → ''
+    expect(cells[3]).toBe('"Kurk"'); // Insole Type → legacy default
+    expect(cells[4]).toBe('"2"'); // No. of Insoles → legacy default
+    expect(cells[6]).toBe('"00:00:00"'); // Total Duration → 0
+    expect(cells[7]).toBe('"00:00:00"'); // Paused Duration → 0
+    expect(cells[9]).toBe('""'); // End Time → '' (null end)
+  });
+
+  it('escapes commas, quotes and newlines inside a field', () => {
+    const tricky: SessionCsvRow = { ...row, activityName: 'Frezen, "spoed"\n2e regel' };
+    const csv = buildSessionsCsv([tricky]);
+    // Comma stays inside the quoted cell, embedded quotes are doubled, newline is preserved.
+    expect(csv).toContain('"Frezen, ""spoed""\n2e regel"');
+  });
+});
+
+describe('csv helpers (edges)', () => {
+  it('quote wraps and escapes commas, quotes and newlines', () => {
+    expect(quote('a,b')).toBe('"a,b"');
+    expect(quote('a"b')).toBe('"a""b"');
+    expect(quote('a\nb')).toBe('"a\nb"');
+  });
+
+  it('formatDuration renders zero and lets hours exceed 99', () => {
+    expect(formatDuration(0)).toBe('00:00:00');
+    expect(formatDuration(3661)).toBe('01:01:01');
+    expect(formatDuration(360000)).toBe('100:00:00');
+  });
 });
diff --git a/apps/api/test/export.test.ts b/apps/api/test/export.test.ts
index 8e3f042..5728fb1 100644
--- a/apps/api/test/export.test.ts
+++ b/apps/api/test/export.test.ts
@@ -1,11 +1,11 @@
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, beforeEach } from 'vitest';
 import type { Hono } from 'hono';
 import { createApp } from '../src/app';
 import { db } from '../src/db/client';
 import { workSessions } from '../src/db/schema';
 import { eq } from 'drizzle-orm';
 import { quote, formatDuration } from '../src/lib/csv';
-import { authToken, bearer, seedActivity } from './helpers';
+import { authToken, bearer, seedActivity, resetDb } from './helpers';
 
 // Start a session, backdate its start_time by `durationSeconds`, then stop it,
 // producing a completed session with an exact duration.
@@ -31,6 +31,8 @@ async function completedSession(
 }
 
 describe('csv export', () => {
+  beforeEach(resetDb);
+
   it('401s without a token', async () => {
     const app = createApp();
     const res = await app.request('/api/export');
@@ -118,6 +120,32 @@ describe('csv export', () => {
     const lines = (await res.text()).split('\n');
     expect(lines).toHaveLength(2); // header + 1 completed row
   });
+
+  it('orders rows by start time ascending', async () => {
+    const app = createApp();
+    const token = await authToken(app, 'export-order@example.com');
+    const frezenId = await seedActivity('Frezen');
+    const slijpenId = await seedActivity('Slijpen');
+
+    // Two completed sessions; make Frezen clearly the older start.
+    const older = await completedSession(app, token, frezenId, 'Kurk', 30);
+    const newer = await completedSession(app, token, slijpenId, 'Berk', 30);
+    await db
+      .update(workSessions)
+      .set({ startTime: new Date(Date.now() - 60000) })
+      .where(eq(workSessions.id, older));
+    await db
+      .update(workSessions)
+      .set({ startTime: new Date(Date.now() - 10000) })
+      .where(eq(workSessions.id, newer));
+
+    const lines = (
+      await (await app.request('/api/export', { headers: bearer(token) })).text()
+    ).split('\n');
+    expect(lines).toHaveLength(3); // header + 2 rows
+    expect(lines[1]).toContain('"Frezen"'); // oldest start first
+    expect(lines[2]).toContain('"Slijpen"');
+  });
 });
 
 describe('csv helpers', () => {
diff --git a/docs/reference/domain-test-checklist.md b/docs/reference/domain-test-checklist.md
index f8a6482..0919dc6 100644
--- a/docs/reference/domain-test-checklist.md
+++ b/docs/reference/domain-test-checklist.md
@@ -127,3 +127,29 @@ Guaranteed behaviors:
 - Lifecycle: start → pause → (backdate) resume accumulates paused time → (backdate) stop excludes
   paused time from worked duration → the completed session appears in history with its activity
   name → `GET /api/export` returns a CSV with exactly the header + one data row.
+
+## Worker export/CSV
+
+Src covered: `src/lib/csv.ts` — 100% stmts/branch/funcs/lines; the `/api/export` route in
+`src/routes/sessions.ts` — 100%. No `c8 ignore`s needed (every fallback branch is exercised).
+
+Guaranteed behaviors:
+
+- `buildSessionsCsv(rows)` (worker self-export, `includeWorker` defaults to false) emits the exact
+  legacy header `ID,Task,Insole Type,No. of Insoles,Date,Total Duration,Paused Duration,Start
+  Time,End Time` (each cell quoted) with no Worker column.
+- `buildSessionsCsv(rows, { includeWorker: true })` prepends a `Worker` column carrying `userName`.
+- Every field is quoted; `quote` escapes embedded double quotes (doubled) and keeps commas and
+  newlines inside the quoted cell — a comma/quote/newline in an activity name never breaks the
+  column or row structure.
+- Legacy fallbacks: a null `activityName`/`userName` renders `''`, null `insoleType` renders
+  `Kurk`, null `pairCount` renders `2`, null `durationSeconds`/`pausedSeconds` render `00:00:00`,
+  and a null `endTime` renders an empty End Time cell.
+- `formatDuration` renders zero-padded `HH:MM:SS`, handles zero (`00:00:00`), and lets hours exceed
+  99 (`360000 → 100:00:00`).
+- `GET /api/export`: 401 without a token; includes only the caller's `completed` sessions
+  (active/discarded and other users' rows excluded); rows ordered by start time ascending; sets the
+  `text/csv` content-type and the `attachment; filename="insole-production-report.csv"` disposition
+  header.
+- Lifecycle: covered by the worker-session anchor (`test/integration/worker-session-lifecycle.test.ts`),
+  whose final step asserts `GET /api/export` returns the header + exactly one completed-session row.