test(e2e): sprint 6 acceptance — US-29 / US-30 / US-31

Adds 3 Playwright spec files covering all 13 ACs for the engagement
export feature:
- us29-export-formats.spec.ts (8 tests): dropdown, md/csv/pdf downloads,
  admin + redteam, filename convention
- us30-export-rbac.spec.ts (3 tests): SOC button absent, SOC 403, no-token 401
- us31-export-robustness.spec.ts (4 tests): missing format 400, bad format 400,
  unknown engagement 404, zero-sim export OK

Total: 201 → 223 Playwright tests. No regressions on sprints 1–5.

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

e2e/tests/us31-export-robustness.spec.ts

@@ -0,0 +1,176 @@
+/**
+ * US-31 — Export robustness: format validation and edge cases.
+ *
+ * All 4 ACs use direct API calls (no UI needed) for speed and determinism.
+ *
+ * AC-31.1: missing ?format → 400 friendly message
+ * AC-31.2: ?format=xml → 400 friendly message
+ * AC-31.3: engagement 99999 → 404
+ * AC-31.4: engagement with 0 simulations → export OK (CSV = 1 header row only)
+ */
+import { test, expect } from '@playwright/test';
+import {
+  adminToken,
+  createEngagement,
+  deleteEngagement,
+  deleteUserByUsername,
+  ensureUser,
+  login,
+  makeClient,
+} from '../fixtures/api';
+
+const ADMIN_USER = 'us31-admin';
+const PASS = 'us31-pass-strong!';
+
+const BASE_URL = process.env.MIMIC_BASE_URL ?? 'http://localhost:5000';
+
+/**
+ * RFC-4180-aware row counter — same logic as us29 helper.
+ * Embedded newlines inside quoted cells are not counted as row breaks.
+ */
+function countCsvRows(csv: string): number {
+  let inQuote = false;
+  let rowCount = 0;
+  let lineStart = 0;
+
+  for (let i = 0; i < csv.length; i++) {
+    const ch = csv[i];
+    if (ch === '"') {
+      if (inQuote && csv[i + 1] === '"') {
+        i++;
+      } else {
+        inQuote = !inQuote;
+      }
+    } else if ((ch === '\n' || ch === '\r') && !inQuote) {
+      if (ch === '\r' && csv[i + 1] === '\n') i++;
+      const line = csv.slice(lineStart, i).trim();
+      if (line.length > 0) rowCount++;
+      lineStart = i + 1;
+    }
+  }
+  const tail = csv.slice(lineStart).trim();
+  if (tail.length > 0) rowCount++;
+  return rowCount;
+}
+
+test.describe('US-31 — Export robustness', () => {
+  let adminTok: string;
+
+  test.beforeAll(async () => {
+    await ensureUser(ADMIN_USER, PASS, 'admin');
+    adminTok = (await login(ADMIN_USER, PASS)).token;
+  });
+
+  test.afterAll(async () => {
+    try {
+      const rootTok = await adminToken();
+      await deleteUserByUsername(rootTok, ADMIN_USER);
+    } catch { /* noop */ }
+  });
+
+  // AC-31.1 — missing format → 400
+  test('AC-31.1 — GET /export without format → 400 with friendly error', async ({
+    request,
+  }) => {
+    // Need a valid engagement id — use admin to create one transiently
+    const engagement = await createEngagement(adminTok, {
+      name: 'US31 missing format eng',
+      start_date: '2026-01-01',
+    });
+
+    try {
+      const response = await request.get(
+        `${BASE_URL}/api/engagements/${engagement.id}/export`,
+        { headers: { Authorization: `Bearer ${adminTok}` } },
+      );
+      expect(response.status()).toBe(400);
+      const body = await response.json();
+      expect(body).toHaveProperty('error');
+      expect(body.error).toMatch(/format/i);
+    } finally {
+      await deleteEngagement(adminTok, engagement.id);
+    }
+  });
+
+  // AC-31.2 — unknown format → 400
+  test('AC-31.2 — GET /export?format=xml → 400 with friendly error', async ({
+    request,
+  }) => {
+    const engagement = await createEngagement(adminTok, {
+      name: 'US31 bad format eng',
+      start_date: '2026-01-01',
+    });
+
+    try {
+      const response = await request.get(
+        `${BASE_URL}/api/engagements/${engagement.id}/export?format=xml`,
+        { headers: { Authorization: `Bearer ${adminTok}` } },
+      );
+      expect(response.status()).toBe(400);
+      const body = await response.json();
+      expect(body).toHaveProperty('error');
+      expect(body.error).toMatch(/format/i);
+    } finally {
+      await deleteEngagement(adminTok, engagement.id);
+    }
+  });
+
+  // AC-31.3 — unknown engagement → 404
+  test('AC-31.3 — GET /engagements/99999/export?format=md → 404', async ({
+    request,
+  }) => {
+    const response = await request.get(
+      `${BASE_URL}/api/engagements/99999/export?format=md`,
+      { headers: { Authorization: `Bearer ${adminTok}` } },
+    );
+    expect(response.status()).toBe(404);
+  });
+
+  // AC-31.4 — engagement with 0 simulations: export OK
+  test('AC-31.4 — engagement with 0 simulations: Markdown export OK (header only)', async ({
+    request,
+  }) => {
+    const engagement = await createEngagement(adminTok, {
+      name: 'US31 empty engagement',
+      start_date: '2026-01-01',
+    });
+
+    try {
+      const response = await request.get(
+        `${BASE_URL}/api/engagements/${engagement.id}/export?format=md`,
+        { headers: { Authorization: `Bearer ${adminTok}` } },
+      );
+      expect(response.status()).toBe(200);
+      const text = await response.text();
+      // Must contain engagement name in the header section
+      expect(text).toContain('US31 empty engagement');
+    } finally {
+      await deleteEngagement(adminTok, engagement.id);
+    }
+  });
+
+  test('AC-31.4 — engagement with 0 simulations: CSV export has only 1 header row', async ({
+    request,
+  }) => {
+    const engagement = await createEngagement(adminTok, {
+      name: 'US31 empty CSV engagement',
+      start_date: '2026-01-01',
+    });
+
+    try {
+      const response = await request.get(
+        `${BASE_URL}/api/engagements/${engagement.id}/export?format=csv`,
+        { headers: { Authorization: `Bearer ${adminTok}` } },
+      );
+      expect(response.status()).toBe(200);
+      const text = await response.text();
+      // Count rows via RFC-4180-aware counter (handles embedded newlines in quoted cells)
+      const rowCount = countCsvRows(text);
+      expect(rowCount).toBe(1);
+      // The single row is the header; must contain 'name' column
+      expect(text.trim()).toContain('name');
+    } finally {
+      await deleteEngagement(adminTok, engagement.id);
+    }
+  });
+});