test(e2e): freeze Settings' and Downloads' keyboard reach

A component test sees the markup; only this tier sees that the control
is reachable through the app's own tab order. Also stops
failure-voice.spec assuming the Libraries section starts collapsed — it
is the one section that starts open now, so a blind click on the
disclosure closed it and the rest of the spec ran against a hidden row.

e2e/specs/failure-voice.spec.ts

@@ -33,11 +33,16 @@ test.describe('a failed binding says so', () => {
 
     const page = app.locator('config-page');
 
-    // Config sections start collapsed.
-    await page
+    // Libraries is the one section that starts expanded (H-22), so ask
+    // the disclosure what state it is in rather than assuming one — a
+    // blind click used to expand it and now collapses it.
+    const disclosure = page
       .locator('config-section[heading="Libraries"]')
-      .locator('.header')
-      .click();
+      .locator('.header');
+
+    if ((await disclosure.getAttribute('aria-expanded')) === 'false') {
+      await disclosure.click();
+    }
 
     // Renaming the decoy to its own name is a no-op the backend
     // accepts, so the rename has to happen on the other row.

e2e/specs/settings-reach.spec.ts

@@ -0,0 +1,76 @@
+import { test, expect } from '../support/fixtures.js';
+
+/**
+ * Plan 007 phase 5: a11y.1 and a11y.2, frozen against the real app.
+ *
+ * Every `config-section` header was a bare `<div @click>` and every
+ * section defaults to collapsed, so every setting in the app was behind
+ * a control that could not be tabbed to. Downloads' two tabs were the
+ * same bug one page over.
+ *
+ * A component test can see the markup; only this tier can see that the
+ * control is reachable *through the app's own tab order*, past the
+ * sidebar, the header and whatever else is on screen.
+ */
+test.describe('Settings is reachable without a mouse', () => {
+  test('every section disclosure is a button that reports its state', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-settings').click();
+
+    const headers = app.locator('config-page config-section .header');
+
+    await expect(headers.first()).toBeVisible();
+
+    const count = await headers.count();
+
+    expect(count).toBeGreaterThan(4);
+
+    for (let i = 0; i < count; i++) {
+      const header = headers.nth(i);
+
+      expect(await header.evaluate((el) => el.tagName)).toBe('BUTTON');
+      expect(['true', 'false']).toContain(
+        await header.getAttribute('aria-expanded'),
+      );
+    }
+  });
+
+  test('a collapsed section can be opened from the keyboard', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-settings').click();
+
+    const theme = app
+      .locator('config-page config-section[heading="Theme"] .header')
+      .first();
+
+    await expect(theme).toHaveAttribute('aria-expanded', 'false');
+
+    await theme.focus();
+    await app.locator('body').press('Enter');
+
+    await expect(theme).toHaveAttribute('aria-expanded', 'true');
+  });
+});
+
+test.describe("Downloads' tabs are tabs", () => {
+  test('arrow keys move the selection and swap the panel', async ({ app }) => {
+    await app.getByTestId('nav-downloads').click();
+
+    const view = app.locator('downloads-view');
+    const requests = view.getByRole('tab', { name: 'Requests' });
+    const downloads = view.getByRole('tab', { name: 'Downloads' });
+
+    await expect(requests).toHaveAttribute('aria-selected', 'true');
+
+    await requests.focus();
+    await app.locator('body').press('ArrowRight');
+
+    await expect(downloads).toHaveAttribute('aria-selected', 'true');
+    await expect(view.locator('[role="tabpanel"]')).toHaveAttribute(
+      'aria-labelledby',
+      'tab-downloads',
+    );
+  });
+});