test(e2e): autosuggest journeys, gated on the flag

Feature state is read from its observable effect — whether the search
box is a combobox — because /api/flags is denied to the public on
purpose. Same approach as the distance journeys.

The three endpoint tests are ungated: /api/suggest is live whether or
not the UI is, which is what lets it be smoke-tested in an environment
where the feature is still dark.

The flag-off journey asserts the plain search still works, not just that
the combobox is absent. Verified against staging, where the flag is off:
it passes and the flag-on journey correctly skips.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015mWQnpye9F299NVRCCSRvj

e2e/tests/journeys.spec.ts

@@ -2111,3 +2111,66 @@ test('the rankings page still orders by score, not name', async ({ page }) => {
     .filter((v: number | null) => v != null);
   expect(scores).toEqual([...scores].sort((a: number, b: number) => b - a));
 });
+
+/*
+ * School autosuggest (spec 2026-08-26).
+ */
+async function autosuggestIsOn(page: Page): Promise<boolean> {
+  await page.goto('/');
+  return (await page.getByRole('combobox').count()) > 0;
+}
+
+test('the suggest endpoint answers from Typesense', async ({ page }) => {
+  // Not flagged — the endpoint is live even while the UI is dark, so it can
+  // be smoke-tested before the feature is switched on.
+  const res = await page.request.get('/api/suggest?q=brecknock');
+  expect(res.ok()).toBeTruthy();
+  const { suggestions } = await res.json();
+  expect(Array.isArray(suggestions)).toBeTruthy();
+  if (suggestions.length) {
+    // Local authority is what tells two "St Mary's" apart.
+    expect(suggestions[0]).toHaveProperty('school_name');
+    expect(suggestions[0]).toHaveProperty('local_authority');
+  }
+});
+
+test('a one-character query is answered, not rejected', async ({ page }) => {
+  // The keystroke path never errors on ordinary input.
+  const res = await page.request.get('/api/suggest?q=b');
+  expect(res.status()).toBe(200);
+  expect((await res.json()).suggestions).toEqual([]);
+});
+
+test('the suggest response is cacheable', async ({ page }) => {
+  const res = await page.request.get('/api/suggest?q=brecknock');
+  expect(res.headers()['cache-control'] ?? '').toContain('s-maxage');
+});
+
+test('typing a school name suggests it, and choosing it opens that school', async ({ page }) => {
+  test.skip(!(await autosuggestIsOn(page)),
+    'the school_autosuggest flag is off in this environment');
+
+  // A school certain to exist in any environment with data.
+  const { schools } = await (await page.request.get('/api/schools?page_size=1')).json();
+  test.skip(!schools?.length, 'no schools in this environment');
+  const name = schools[0].school_name as string;
+
+  await page.goto('/');
+  await page.getByRole('combobox').first().fill(name.slice(0, 12));
+  const option = page.getByRole('option').first();
+  await expect(option).toBeVisible();
+  await option.click();
+  await expect(page).toHaveURL(/\/school\/\d+/);
+});
+
+test('with autosuggest off, the search box is a plain input', async ({ page }) => {
+  test.skip(await autosuggestIsOn(page),
+    'the school_autosuggest flag is on in this environment');
+
+  await page.goto('/');
+  await expect(page.getByRole('combobox')).toHaveCount(0);
+  // And the box still works: the existing search must be untouched.
+  await page.getByPlaceholder(/School name or postcode/i).first().fill('abbey');
+  await page.getByRole('button', { name: /Search/i }).first().click();
+  await expect(page).toHaveURL(/search=abbey/);
+});