test: add E2E tests for teacher selection flow and role switch

- Add test: switching from teacher to student auto-selects teacher
- Add test: teacher selection doesn't loop back to org select
- Update existing tests to verify auto-select behavior
- Verify teacher name displayed (not "未选择老师") on profile

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/teacher-switching.spec.ts

@@ -105,6 +105,9 @@ test.describe('学生老师切换', () => {
     const teacherText = await teacherSection.locator('span').first().textContent();
     expect(teacherText).toContain('当前老师');
 
+    // Verify auto-select: teacher name should be displayed (not "未选择老师")
+    expect(teacherText).not.toContain('未选择老师');
+
     // Check switch button
     const switchBtn = teacherSection.locator('.van-button');
     await expect(switchBtn).toBeVisible({ timeout: 10_000 });
@@ -155,4 +158,150 @@ test.describe('学生老师切换', () => {
     const teacherCount = await teacherCells.count();
     expect(teacherCount).toBeGreaterThan(0);
   });
+
+  test('从老师切换到学生角色后显示老师选择页面', async ({ page }) => {
+    test.setTimeout(180_000);
+
+    // Login as student to establish session
+    await loginAsStudent(page);
+
+    // Navigate to profile
+    await page.goto('/student/profile', {
+      waitUntil: 'domcontentloaded',
+      timeout: 60_000,
+    });
+    await expect(page.locator('#app')).toBeVisible({ timeout: 60_000 });
+    await page.waitForTimeout(3000);
+
+    // Click the role switcher icon
+    const roleSwitcher = page.locator('.van-icon-exchange');
+    if (!(await roleSwitcher.isVisible().catch(() => false))) {
+      test.skip(true, '未找到角色切换按钮');
+      return;
+    }
+    await roleSwitcher.click();
+    await page.waitForTimeout(1000);
+
+    // Select TEACHER role
+    const teacherRoleBtn = page.locator('.van-action-sheet__item').filter({ hasText: '老师' });
+    if (!(await teacherRoleBtn.isVisible().catch(() => false))) {
+      test.skip(true, '未找到老师角色选项');
+      return;
+    }
+    await teacherRoleBtn.click();
+    await page.waitForTimeout(1500);
+
+    // Handle confirm dialog if shown
+    const confirmDialog = page.locator('.van-dialog__confirm');
+    if (await confirmDialog.isVisible().catch(() => false)) {
+      await confirmDialog.click();
+      await page.waitForTimeout(5000);
+    }
+
+    // Wait for role switch to complete
+    await expect(page.locator('#app')).toBeVisible({ timeout: 60_000 });
+    await page.waitForTimeout(3000);
+
+    // Navigate to teacher profile to ensure we're in teacher context
+    await page.goto('/teacher/profile', {
+      waitUntil: 'domcontentloaded',
+      timeout: 60_000,
+    });
+    await expect(page.locator('#app')).toBeVisible({ timeout: 60_000 });
+    await page.waitForTimeout(3000);
+
+    if (await page.getByText('请返回微信小程序完成登录').isVisible().catch(() => false)) {
+      test.skip(true, '老师会话不可用');
+      return;
+    }
+
+    // Now switch back to STUDENT role
+    const roleSwitcher2 = page.locator('.van-icon-exchange');
+    if (!(await roleSwitcher2.isVisible().catch(() => false))) {
+      test.skip(true, '未找到角色切换按钮');
+      return;
+    }
+    await roleSwitcher2.click();
+    await page.waitForTimeout(1000);
+
+    // Select STUDENT role
+    const studentRoleBtn = page.locator('.van-action-sheet__item').filter({ hasText: '学生' });
+    if (!(await studentRoleBtn.isVisible().catch(() => false))) {
+      test.skip(true, '未找到学生角色选项');
+      return;
+    }
+    await studentRoleBtn.click();
+    await page.waitForTimeout(1500);
+
+    // Handle confirm dialog
+    const confirmDialog2 = page.locator('.van-dialog__confirm');
+    if (await confirmDialog2.isVisible().catch(() => false)) {
+      await confirmDialog2.click();
+      await page.waitForTimeout(5000);
+    }
+
+    // Wait for role switch to complete
+    await expect(page.locator('#app')).toBeVisible({ timeout: 60_000 });
+    await page.waitForTimeout(5000);
+
+    // We should be on teacher-select page or index page (both show teacher selection)
+    const currentPath = new URL(page.url()).pathname;
+    const validPaths = ['/student/teacher-select', '/'];
+    expect(validPaths).toContain(currentPath);
+
+    // Verify we did NOT end up on org-select page
+    expect(currentPath).not.toBe('/org/select');
+
+    // Verify teacher selection UI is present
+    if (currentPath === '/student/teacher-select') {
+      await expect(page.locator('.van-cell').first()).toBeVisible({ timeout: 10_000 });
+      // Select a teacher
+      await page.locator('.van-cell').first().click();
+      await page.waitForTimeout(2000);
+
+      // After selection, verify we're NOT on org-select
+      const afterPath = new URL(page.url()).pathname;
+      expect(afterPath).not.toBe('/org/select');
+    }
+  });
+
+  test('老师选择后不会回到机构选择页面', async ({ page }) => {
+    test.setTimeout(180_000);
+
+    // Login as student
+    await loginAsStudent(page);
+
+    // Navigate to profile and find teacher section
+    await page.goto('/student/profile', {
+      waitUntil: 'domcontentloaded',
+      timeout: 60_000,
+    });
+    await expect(page.locator('#app')).toBeVisible({ timeout: 60_000 });
+    await page.waitForTimeout(3000);
+
+    // Click switch teacher button
+    const switchBtn = page.locator('.current-teacher .van-button');
+    if (!(await switchBtn.isVisible().catch(() => false))) {
+      test.skip(true, '未找到切换老师按钮');
+      return;
+    }
+    await switchBtn.click();
+    await page.waitForTimeout(2000);
+
+    // Verify teacher list shows
+    const teacherCells = page.locator('.van-cell');
+    const teacherCount = await teacherCells.count();
+    expect(teacherCount).toBeGreaterThan(0);
+
+    // Select a teacher
+    await teacherCells.first().click();
+    await page.waitForTimeout(2000);
+
+    // Verify we didn't end up on org-select
+    const afterUrl = page.url();
+    expect(afterUrl).not.toContain('/org/select');
+
+    // Should still be on a valid student page
+    await expect(page.locator('#app')).toBeVisible({ timeout: 60_000 });
+  });
 });