diff --git a/e2e/README.md b/e2e/README.md
index 63c7f91..e946d2c 100644
--- a/e2e/README.md
+++ b/e2e/README.md
@@ -135,7 +135,7 @@ This creates an in-browser authenticator that:
 
 | Variable | Description | Default |
 |----------|-------------|---------|
-| `BASE_URL` | Server URL | `http://localhost:4401` |
+| `BASE_URL` | Server URL | `http://localhost:4404` |
 | `CI` | CI environment flag | - |
 | `CLEANUP_TEST_DB` | Remove test DB after run | `false` |
 
diff --git a/e2e/playwright.config.js b/e2e/playwright.config.js
index 11f5540..eab7aba 100644
--- a/e2e/playwright.config.js
+++ b/e2e/playwright.config.js
@@ -24,7 +24,7 @@ export default defineConfig({
 
   use: {
     // Base URL for the Paskia server
-    baseURL: process.env.BASE_URL || 'http://localhost:4401',
+    baseURL: process.env.BASE_URL || 'http://localhost:4404',
 
     // Collect trace on failure for debugging
     trace: 'on-first-retry',
diff --git a/e2e/tests/passkey.spec.ts b/e2e/tests/10-passkey.spec.ts
similarity index 90%
rename from e2e/tests/passkey.spec.ts
rename to e2e/tests/10-passkey.spec.ts
index b5d4927..ba1cb9b 100644
--- a/e2e/tests/passkey.spec.ts
+++ b/e2e/tests/10-passkey.spec.ts
@@ -10,6 +10,7 @@ import {
   getSessionCookieName,
   saveSessionToken,
   getSavedSessionToken,
+  saveDeviceTokens,
 } from './fixtures/passkey-helpers'
 import type { Page, BrowserContext } from '@playwright/test'
 
@@ -44,7 +45,7 @@ async function setupSessionCookie(page: Page, sessionToken: string): Promise<voi
  */
 
 test.describe('Passkey Authentication E2E', () => {
-  const baseUrl = process.env.BASE_URL || 'http://localhost:4401'
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
 
   test.describe.configure({ mode: 'serial' })
 
@@ -72,6 +73,10 @@ test.describe('Passkey Authentication E2E', () => {
     // Page should load - 401 errors are expected since user is not logged in
     await page.waitForTimeout(500)
 
+    // Take screenshot of the login view
+    await page.screenshot({ path: 'test-results/login-view.png' })
+    console.log('✓ Screenshot saved: test-results/login-view.png')
+
     // Just verify the page loaded without JS errors (network 401s are OK)
     console.log('✓ Auth page loaded successfully')
   })
@@ -109,6 +114,23 @@ test.describe('Passkey Authentication E2E', () => {
     console.log(`✓ Session token: ${sessionToken.substring(0, 4)}...`)
   })
 
+  test('should create device tokens for other tests', async ({ page }) => {
+    test.skip(!sessionToken, 'Requires successful registration')
+
+    // Create a batch of device tokens for API tests to use
+    // Each API test needs its own token to register a passkey in its virtual authenticator
+    const tokenCount = 15  // Enough for all API tests
+    const tokens: string[] = []
+
+    for (let i = 0; i < tokenCount; i++) {
+      const deviceLink = await createDeviceLink(page, baseUrl, sessionToken)
+      tokens.push(deviceLink.token)
+    }
+
+    saveDeviceTokens(tokens)
+    console.log(`✓ Created ${tokens.length} device tokens for API tests`)
+  })
+
   test('should validate the session token', async ({ page }) => {
     // Skip if registration didn't run
     test.skip(!sessionToken, 'Requires successful registration')
@@ -131,6 +153,22 @@ test.describe('Passkey Authentication E2E', () => {
     expect(userInfo.credentials).toBeDefined()
     expect(userInfo.credentials.length).toBeGreaterThanOrEqual(1)
 
+    // Navigate to profile and take screenshot
+    const cookieName = getSessionCookieName()
+    await page.context().addCookies([{
+      name: cookieName,
+      value: sessionToken,
+      domain: 'localhost',
+      path: '/',
+      secure: true,
+      httpOnly: true,
+      sameSite: 'Strict' as const,
+    }])
+    await page.goto('/auth/')
+    await page.waitForSelector('[data-view="profile"]', { timeout: 5000 })
+    await page.screenshot({ path: 'test-results/profile-view.png' })
+    console.log('✓ Screenshot saved: test-results/profile-view.png')
+
     console.log(`✓ User info retrieved: ${userInfo.user.user_name}`)
     console.log(`✓ Credentials count: ${userInfo.credentials.length}`)
   })
@@ -190,7 +228,7 @@ test.describe('Passkey Authentication E2E', () => {
 })
 
 test.describe('Session Management', () => {
-  const baseUrl = process.env.BASE_URL || 'http://localhost:4401'
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
 
   test('should reject invalid session token', async ({ page }) => {
     const cookieName = getSessionCookieName()
@@ -217,7 +255,7 @@ test.describe('Session Management', () => {
 })
 
 test.describe('Device Addition Dialog', () => {
-  const baseUrl = process.env.BASE_URL || 'http://localhost:4401'
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
 
   test.describe.configure({ mode: 'serial' })
 
@@ -269,12 +307,16 @@ test.describe('Device Addition Dialog', () => {
     const qrCanvas = dialog.locator('.qr-code')
     await expect(qrCanvas).toBeVisible()
 
-    // Verify the link is displayed
-    const linkText = dialog.locator('.qr-link p')
-    await expect(linkText).toBeVisible()
-    const linkContent = await linkText.textContent()
-    expect(linkContent).toContain('localhost/auth/')
-    console.log(`✓ Device link displayed: ${linkContent}`)
+    // Verify the link is displayed (text strips scheme, but href has it)
+    const linkElement = dialog.locator('a.qr-link')
+    await expect(linkElement).toBeVisible()
+    const linkText = await linkElement.textContent()
+    const linkHref = await linkElement.getAttribute('href')
+    // Text shows hostname without scheme
+    expect(linkText).toContain('localhost:4404/auth/')
+    // Href includes full URL with scheme
+    expect(linkHref).toContain('http://localhost:4404/auth/')
+    console.log(`✓ Device link displayed: ${linkText} (href: ${linkHref})`)
 
     // Verify expiration warning is shown
     await expect(dialog.locator('.reg-help')).toContainText('Expires')
@@ -364,7 +406,7 @@ test.describe('Device Addition Dialog', () => {
 })
 
 test.describe('ProfileView - Add New Passkey', () => {
-  const baseUrl = process.env.BASE_URL || 'http://localhost:4401'
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
 
   test('should show credentials list in profile', async ({ page }) => {
     const sessionToken = getSavedSessionToken()
@@ -474,7 +516,7 @@ test.describe('ProfileView - Add New Passkey', () => {
 })
 
 test.describe('ProfileView - Multi-Authenticator', () => {
-  const baseUrl = process.env.BASE_URL || 'http://localhost:4401'
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
 
   test('should add passkey from different authenticator', async ({ page }) => {
     const sessionToken = getSavedSessionToken()
@@ -591,26 +633,3 @@ test.describe('ProfileView - Multi-Authenticator', () => {
     }
   })
 })
-
-test.describe('Logout', () => {
-  const baseUrl = process.env.BASE_URL || 'http://localhost:4401'
-
-  test('should logout successfully', async ({ page }) => {
-    const sessionToken = getSavedSessionToken()
-    test.skip(!sessionToken, 'Requires saved session token')
-
-    await logout(page, baseUrl, sessionToken!)
-
-    // Session should no longer be valid
-    const cookieName = getSessionCookieName()
-    const response = await page.request.post(`${baseUrl}/auth/api/validate`, {
-      headers: {
-        'Cookie': `${cookieName}=${sessionToken}`,
-      },
-      failOnStatusCode: false,
-    })
-
-    expect(response.status()).toBe(401)
-    console.log(`✓ Logout successful, session invalidated`)
-  })
-})
diff --git a/e2e/tests/20-api-auth.spec.ts b/e2e/tests/20-api-auth.spec.ts
new file mode 100644
index 0000000..af79770
--- /dev/null
+++ b/e2e/tests/20-api-auth.spec.ts
@@ -0,0 +1,606 @@
+import { test, expect, createVirtualAuthenticator } from './fixtures/virtual-authenticator'
+import {
+  getSessionCookieName,
+  getSavedSessionToken,
+  saveSessionToken,
+  registerPasskey,
+  authenticatePasskey,
+  popDeviceToken,
+  getDeviceTokenCount,
+  logout,
+} from './fixtures/passkey-helpers'
+import type { Page, Frame } from '@playwright/test'
+
+/**
+ * E2E tests for API mode authentication flows.
+ *
+ * These tests simulate the flow used by SPAs when making API calls:
+ * 1. API call returns 401/403 with auth.iframe URL
+ * 2. App shows auth iframe overlay
+ * 3. User authenticates in iframe
+ * 4. Iframe posts 'auth-success' message to parent
+ * 5. App retries original API call
+ *
+ * Note: These tests depend on 10-passkey.spec.ts running first to create device tokens.
+ * Each test that needs authentication uses popDeviceToken() to get a fresh token
+ * and registers its own credential in its virtual authenticator.
+ */
+
+const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
+
+/**
+ * Helper to set up session cookie for a page.
+ */
+async function setupSessionCookie(page: Page, sessionToken: string): Promise<void> {
+  const cookieName = getSessionCookieName()
+  await page.context().addCookies([{
+    name: cookieName,
+    value: sessionToken,
+    domain: 'localhost',
+    path: '/',
+    secure: true,
+    httpOnly: true,
+    sameSite: 'Strict' as const,
+  }])
+}
+
+/**
+ * Helper to clear session cookie.
+ */
+async function clearSessionCookie(page: Page): Promise<void> {
+  const cookieName = getSessionCookieName()
+  await page.context().clearCookies({ name: cookieName })
+}
+
+/**
+ * Set up the test page using the examples page directly.
+ * The examples page already has iframe handling - we just add a Promise wrapper.
+ */
+async function setupTestHarness(page: Page): Promise<void> {
+  // Navigate to the examples page which already has the auth iframe handling
+  await page.goto(`${baseUrl}/auth/examples/`)
+}
+
+/**
+ * Make an API call through the examples page, returning a Promise.
+ * Wraps the page's apiCall and listens for auth-success/auth-back messages.
+ * Returns { status, data } on success, or throws on cancellation.
+ *
+ * Note: If auth is not needed (request succeeds without 401/403), this will
+ * resolve after a timeout with the direct fetch result.
+ */
+async function makeApiCall(page: Page, url: string, method = 'GET'): Promise<{ status: number; data?: any }> {
+  return page.evaluate(({ url, method }) => {
+    return new Promise((resolve, reject) => {
+      let resolved = false;
+
+      // Listen for auth messages
+      const handler = (event: MessageEvent) => {
+        const { type } = event.data || {};
+        if (type === 'auth-success') {
+          if (resolved) return;
+          resolved = true;
+          window.removeEventListener('message', handler);
+          // Wait a tick for the page's handler to retry, then make our own call
+          setTimeout(async () => {
+            try {
+              const response = await fetch(url, { method, credentials: 'include' });
+              if (response.status === 204) {
+                resolve({ status: 204 });
+              } else if (response.ok) {
+                const data = await response.json();
+                resolve({ status: response.status, data });
+              } else {
+                resolve({ status: response.status });
+              }
+            } catch (e) {
+              resolve({ status: 0 });
+            }
+          }, 200);
+        } else if (type === 'auth-back') {
+          if (resolved) return;
+          resolved = true;
+          window.removeEventListener('message', handler);
+          reject(new Error('cancelled'));
+        }
+      };
+      window.addEventListener('message', handler);
+
+      // Also make a direct fetch to handle the case where no auth is needed
+      // (the page's apiCall won't send any message if the request succeeds)
+      setTimeout(async () => {
+        if (resolved) return;
+        try {
+          const response = await fetch(url, { method, credentials: 'include' });
+          // Only resolve if this is a success or non-auth error
+          if (response.status !== 401 && response.status !== 403) {
+            if (resolved) return;
+            resolved = true;
+            window.removeEventListener('message', handler);
+            if (response.status === 204) {
+              resolve({ status: 204 });
+            } else if (response.ok) {
+              const data = await response.json();
+              resolve({ status: response.status, data });
+            } else {
+              resolve({ status: response.status });
+            }
+          }
+          // If 401/403, the auth iframe will appear and we wait for the message
+        } catch (e) {
+          // Network error - let the message handler deal with it
+        }
+      }, 100);
+
+      // Call the page's existing apiCall function
+      // It will show the iframe on 401/403
+      (window as any).apiCall(url, method);
+    });
+  }, { url, method });
+}
+
+/**
+ * Wait for auth iframe to appear and return a reference to it.
+ */
+async function waitForAuthIframe(page: Page, timeout = 5000): Promise<Frame> {
+  await page.waitForSelector('#auth-iframe', { timeout })
+  const iframe = page.frameLocator('#auth-iframe')
+  // Wait for iframe content to load
+  await iframe.locator('.view-root').waitFor({ timeout })
+  return page.frame({ url: /\/auth\/restricted\// })!
+}
+
+/**
+ * Wait for auth iframe to disappear.
+ */
+async function waitForAuthIframeHidden(page: Page, timeout = 5000): Promise<void> {
+  await page.waitForSelector('#auth-iframe', { state: 'detached', timeout })
+}
+
+/**
+ * Click Back button in auth iframe.
+ */
+async function clickBackInIframe(page: Page): Promise<void> {
+  const iframe = page.frameLocator('#auth-iframe')
+  await iframe.getByRole('button', { name: 'Back' }).click()
+}
+
+/**
+ * Click Login button in auth iframe.
+ */
+async function clickLoginInIframe(page: Page): Promise<void> {
+  const iframe = page.frameLocator('#auth-iframe')
+  await iframe.getByRole('button', { name: 'Login' }).click()
+}
+
+/**
+ * Click Verify button in auth iframe (for reauth mode).
+ */
+async function clickVerifyInIframe(page: Page): Promise<void> {
+  const iframe = page.frameLocator('#auth-iframe')
+  await iframe.getByRole('button', { name: 'Verify' }).click()
+}
+
+/**
+ * Click Logout button in auth iframe (for forbidden mode).
+ */
+async function clickLogoutInIframe(page: Page): Promise<void> {
+  const iframe = page.frameLocator('#auth-iframe')
+  await iframe.getByRole('button', { name: 'Logout' }).click()
+}
+
+test.describe('API Mode - 401 Login Flow', () => {
+  test.describe.configure({ mode: 'serial' })
+
+  test('should show auth iframe on 401 and allow cancellation (Back)', async ({ page }) => {
+    // Set up test harness (injects our API flow handler)
+    await setupTestHarness(page)
+
+    // Clear any existing session cookie
+    await clearSessionCookie(page)
+
+    // Make API call that triggers 401 (don't await - it blocks until iframe resolves)
+    const apiCallPromise = makeApiCall(page, '/auth/api/user-info', 'POST').catch(e => e)
+    console.log('✓ Auth iframe appeared on 401')
+
+    // Verify it's in login mode (not reauth)
+    const iframe = page.frameLocator('#auth-iframe')
+    await expect(iframe.locator('h1')).toContainText('🔐')
+    await expect(iframe.getByRole('button', { name: 'Login' })).toBeVisible()
+
+    // Take screenshot of the login iframe
+    await page.screenshot({ path: 'test-results/api-401-login-iframe.png' })
+    console.log('✓ Screenshot saved: test-results/api-401-login-iframe.png')
+
+    // Click Back to cancel authentication
+    await clickBackInIframe(page)
+
+    // Iframe should close
+    await waitForAuthIframeHidden(page)
+    console.log('✓ Auth iframe closed on Back button')
+
+    // Wait for the API call promise to reject
+    const result = await apiCallPromise
+    expect(result).toBeInstanceOf(Error)
+    expect(result.message).toContain('cancelled')
+
+    // Output should show cancellation
+    const output = page.locator('#output')
+    await expect(output).toContainText('cancelled')
+    console.log('✓ API call was cancelled')
+  })
+
+  test('should show auth iframe on 401 and complete login', async ({ page, virtualAuthenticator }) => {
+    // Get a device token from the pool (created by 10-passkey.spec.ts)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'Requires device token from passkey tests')
+    console.log(`✓ Got device token: ${deviceToken} (${getDeviceTokenCount()} remaining)`)
+
+    // Navigate and register credential using device token
+    await page.goto(`${baseUrl}/auth/`)
+    const regResult = await registerPasskey(page, baseUrl, {
+      resetToken: deviceToken,
+      displayName: 'API Test Device',
+    })
+    console.log(`✓ Registered credential: ${regResult.credential_uuid}`)
+
+    // Logout to clear session (but keep the passkey in virtual authenticator)
+    await logout(page, baseUrl, regResult.session_token)
+    console.log('✓ Logged out')
+
+    // Set up test harness
+    await setupTestHarness(page)
+
+    // Make API call that triggers 401
+    const apiCallPromise = makeApiCall(page, '/auth/api/user-info', 'POST')
+
+    // Wait for auth iframe to appear
+    await waitForAuthIframe(page)
+    console.log('✓ Auth iframe appeared on 401')
+
+    // Click Login button - virtual authenticator will handle the passkey
+    await clickLoginInIframe(page)
+
+    // Wait for authentication to complete - iframe should close
+    await waitForAuthIframeHidden(page, 10000)
+    console.log('✓ Authentication completed, iframe closed')
+
+    // Wait for API call to complete and verify result
+    const result = await apiCallPromise
+    expect(result.status).toBe(200)
+    expect(result.data.user).toBeDefined()
+    console.log('✓ API call succeeded after authentication')
+
+    // Save the session for other tests
+    const cookies = await page.context().cookies()
+    const sessionCookie = cookies.find(c => c.name === getSessionCookieName())
+    if (sessionCookie) {
+      saveSessionToken(sessionCookie.value)
+      console.log(`✓ Saved session token for other tests`)
+    }
+  })
+})
+
+test.describe('API Mode - 401 Reauth Flow', () => {
+  test.describe.configure({ mode: 'serial' })
+
+  test('should show reauth iframe on max_age violation and allow cancellation', async ({ page, virtualAuthenticator }) => {
+    // Get a device token from the pool (created by 10-passkey.spec.ts)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'Requires device token from passkey tests')
+    console.log(`✓ Got device token: ${deviceToken} (${getDeviceTokenCount()} remaining)`)
+
+    // Navigate and register a credential
+    await page.goto(`${baseUrl}/auth/`)
+    const regResult = await registerPasskey(page, baseUrl, {
+      resetToken: deviceToken,
+      displayName: 'Reauth Cancel Test Device',
+    })
+    saveSessionToken(regResult.session_token)
+
+    // Wait for session to age past max_age threshold
+    console.log('Waiting 3s for session to age...')
+    await page.waitForTimeout(3000)
+
+    // Set up test harness with the session
+    await setupSessionCookie(page, regResult.session_token)
+    await setupTestHarness(page)
+
+    // Make API call with max_age=1s (session is now > 1s old)
+    const apiCallPromise = makeApiCall(page, '/auth/api/forward?max_age=1s', 'GET').catch(e => e)
+
+    // Wait for auth iframe to appear
+    await waitForAuthIframe(page)
+    console.log('✓ Reauth iframe appeared (session older than max_age)')
+
+    // Verify it's in reauth mode
+    const iframe = page.frameLocator('#auth-iframe')
+    await expect(iframe.locator('h1')).toContainText('Additional Authentication')
+    await expect(iframe.getByRole('button', { name: 'Verify' })).toBeVisible()
+
+    // Take screenshot of reauth iframe
+    await page.screenshot({ path: 'test-results/api-401-reauth-iframe.png' })
+    console.log('✓ Screenshot saved: test-results/api-401-reauth-iframe.png')
+
+    // Click Back to cancel
+    await clickBackInIframe(page)
+    await waitForAuthIframeHidden(page)
+    console.log('✓ Reauth cancelled via Back button')
+
+    const result = await apiCallPromise
+    expect(result).toBeInstanceOf(Error)
+  })
+
+  test('should complete reauth flow with passkey', async ({ page, virtualAuthenticator }) => {
+    // Get a device token from the pool (created by 10-passkey.spec.ts)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'Requires device token from passkey tests')
+    console.log(`✓ Got device token: ${deviceToken} (${getDeviceTokenCount()} remaining)`)
+
+    // Navigate and register a credential
+    await page.goto(`${baseUrl}/auth/`)
+    const regResult = await registerPasskey(page, baseUrl, {
+      resetToken: deviceToken,
+      displayName: 'Reauth Test Device',
+    })
+
+    // Save the new session
+    saveSessionToken(regResult.session_token)
+
+    // Wait for the session to be "old" (>2s for max_age=2s test)
+    console.log('Waiting 3s for session to age...')
+    await page.waitForTimeout(3000)
+
+    // Set up test harness with the session
+    await setupSessionCookie(page, regResult.session_token)
+    await setupTestHarness(page)
+
+    // Make API call with max_age=2s
+    const apiCallPromise = makeApiCall(page, '/auth/api/forward?max_age=2s', 'GET')
+
+    // Auth iframe should appear in reauth mode
+    await waitForAuthIframe(page)
+    console.log('✓ Reauth iframe appeared')
+
+    const iframe = page.frameLocator('#auth-iframe')
+    await expect(iframe.locator('h1')).toContainText('Additional Authentication')
+
+    // Click Verify - virtual authenticator handles passkey
+    await clickVerifyInIframe(page)
+
+    // Wait for completion
+    await waitForAuthIframeHidden(page, 10000)
+    console.log('✓ Reauth completed')
+
+    // Wait for API call result
+    const result = await apiCallPromise
+    expect(result.status).toBe(204)
+    console.log('✓ Forward endpoint returned 204 after reauth')
+  })
+})
+
+test.describe('API Mode - 403 Forbidden Flow', () => {
+  test.describe.configure({ mode: 'serial' })
+
+  test('should show forbidden view and allow going back', async ({ page }) => {
+    const sessionToken = getSavedSessionToken()
+    test.skip(!sessionToken, 'Requires saved session token')
+
+    // Set up test harness with valid session
+    await setupSessionCookie(page, sessionToken!)
+    await setupTestHarness(page)
+
+    // Make API call requiring admin permission
+    const apiCallPromise = makeApiCall(page, '/auth/api/forward?perm=auth:admin', 'GET').catch(e => e)
+
+    // Check if auth iframe appeared
+    const iframeAppeared = await page.waitForSelector('#auth-iframe', { timeout: 3000 }).then(() => true).catch(() => false)
+
+    if (!iframeAppeared) {
+      // User might already have admin permission
+      const result = await apiCallPromise
+      if (result.status === 204) {
+        console.log('✓ User has admin permission, got 204 (skipping forbidden test)')
+        return
+      }
+    }
+
+    await waitForAuthIframe(page)
+    console.log('✓ Auth iframe appeared on permission check')
+
+    // Wait for view to stabilize and check mode
+    await page.waitForTimeout(500)
+    const iframe = page.frameLocator('#auth-iframe')
+    const headingText = await iframe.locator('h1').textContent()
+    console.log(`  Heading: ${headingText}`)
+
+    if (headingText?.includes('Forbidden')) {
+      console.log('✓ Forbidden view displayed (user lacks admin permission)')
+
+      // Should show Logout button in forbidden mode
+      await expect(iframe.getByRole('button', { name: 'Logout' })).toBeVisible()
+
+      // Take screenshot of forbidden view
+      await page.screenshot({ path: 'test-results/api-403-forbidden-iframe.png' })
+      console.log('✓ Screenshot saved: test-results/api-403-forbidden-iframe.png')
+
+      // Click Back to close
+      await clickBackInIframe(page)
+      await waitForAuthIframeHidden(page)
+      console.log('✓ Forbidden dialog closed via Back')
+
+      const result = await apiCallPromise
+      expect(result).toBeInstanceOf(Error)
+    } else {
+      // User has admin permission, so they got through
+      console.log('✓ User has admin permission, no forbidden view')
+    }
+  })
+
+  test('should allow logout from forbidden view and then login', async ({ page, virtualAuthenticator }) => {
+    // Get a device token from the pool (created by 10-passkey.spec.ts)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'Requires device token from passkey tests')
+    console.log(`✓ Got device token: ${deviceToken} (${getDeviceTokenCount()} remaining)`)
+
+    // Navigate and register credential for later login
+    await page.goto(`${baseUrl}/auth/`)
+    const regResult = await registerPasskey(page, baseUrl, {
+      resetToken: deviceToken,
+      displayName: 'Forbidden Test Device',
+    })
+    saveSessionToken(regResult.session_token)
+
+    // Set up test harness with the session
+    await setupSessionCookie(page, regResult.session_token)
+    await setupTestHarness(page)
+
+    // Make API call requiring admin permission
+    const apiCallPromise = makeApiCall(page, '/auth/api/forward?perm=auth:admin', 'GET').catch(e => e)
+
+    // Check if auth iframe appeared
+    const iframeAppeared = await page.waitForSelector('#auth-iframe', { timeout: 3000 }).then(() => true).catch(() => false)
+
+    if (!iframeAppeared) {
+      const result = await apiCallPromise
+      if (result.status === 204) {
+        console.log('✓ User has admin permission, skipping forbidden->login test')
+        return
+      }
+    }
+
+    await waitForAuthIframe(page)
+    const iframe = page.frameLocator('#auth-iframe')
+    await page.waitForTimeout(500)
+
+    const headingText = await iframe.locator('h1').textContent()
+
+    if (headingText?.includes('Forbidden')) {
+      console.log('✓ Forbidden view displayed')
+
+      // Take screenshot of forbidden view before logout
+      await page.screenshot({ path: 'test-results/api-403-forbidden-before-logout.png' })
+      console.log('✓ Screenshot saved: test-results/api-403-forbidden-before-logout.png')
+
+      // Click Logout in the iframe
+      await clickLogoutInIframe(page)
+
+      // After logout, the view should switch to login mode and show a toast
+      await page.waitForTimeout(1000)
+      await expect(iframe.getByRole('button', { name: 'Login' })).toBeVisible({ timeout: 5000 })
+      console.log('✓ Switched to login view after logout')
+
+      // Verify status message appears indicating user can login with another account
+      const statusMessage = iframe.locator('.global-status .status')
+      await expect(statusMessage).toBeVisible({ timeout: 3000 })
+      const statusText = await statusMessage.textContent()
+      expect(statusText).toContain('sign in with a different account')
+      console.log(`✓ Status message: ${statusText}`)
+
+      // Take screenshot showing login view with status message (after forbidden logout)
+      await page.screenshot({ path: 'test-results/api-403-after-logout-login.png' })
+      console.log('✓ Screenshot saved: test-results/api-403-after-logout-login.png')
+
+      // Now login with the passkey
+      await clickLoginInIframe(page)
+
+      // Wait for auth to complete
+      await waitForAuthIframeHidden(page, 10000)
+      console.log('✓ Logged in successfully')
+
+      // The API call should have completed (but may still fail with 403 since same user)
+      const result = await apiCallPromise
+      console.log(`  Final result status: ${result.status || 'error'}`)
+    } else {
+      console.log('✓ Not in forbidden mode, closing dialog')
+      await clickBackInIframe(page)
+      await waitForAuthIframeHidden(page)
+    }
+  })
+})
+
+test.describe('API Mode - Direct API Response Format', () => {
+  test('should return JSON with auth.iframe on 401 (unauthenticated)', async ({ page }) => {
+    // Make direct API call without session
+    const response = await page.request.get(`${baseUrl}/auth/api/forward`, {
+      headers: {
+        'Accept': 'application/json',
+      },
+    })
+
+    expect(response.status()).toBe(401)
+
+    const data = await response.json()
+    expect(data.auth).toBeDefined()
+    expect(data.auth.iframe).toBeDefined()
+    expect(data.auth.mode).toBe('login')
+    expect(data.auth.iframe).toContain('/auth/restricted/')
+
+    console.log(`✓ 401 response includes auth.iframe: ${data.auth.iframe}`)
+  })
+
+  test('should return JSON with auth.mode=forbidden on 403', async ({ page }) => {
+    const sessionToken = getSavedSessionToken()
+    test.skip(!sessionToken, 'Requires saved session token')
+
+    const cookieName = getSessionCookieName()
+
+    // Make API call with session but requesting admin permission
+    const response = await page.request.get(`${baseUrl}/auth/api/forward?perm=auth:admin`, {
+      headers: {
+        'Accept': 'application/json',
+        'Cookie': `${cookieName}=${sessionToken}`,
+      },
+    })
+
+    // Could be 403 (forbidden) or 204 (user is admin)
+    if (response.status() === 403) {
+      const data = await response.json()
+      expect(data.auth).toBeDefined()
+      expect(data.auth.mode).toBe('forbidden')
+      console.log(`✓ 403 response auth.mode: ${data.auth.mode}`)
+    } else if (response.status() === 204) {
+      console.log('✓ User has admin permission, got 204')
+    } else {
+      console.log(`  Unexpected status: ${response.status()}`)
+    }
+  })
+
+  test('should return JSON with auth.mode=reauth on max_age violation', async ({ page, virtualAuthenticator }) => {
+    // Get a device token from the pool (created by 10-passkey.spec.ts)
+    const deviceToken = popDeviceToken()
+    test.skip(!deviceToken, 'Requires device token from passkey tests')
+    console.log(`✓ Got device token: ${deviceToken} (${getDeviceTokenCount()} remaining)`)
+
+    // Navigate and create fresh session
+    await page.goto(`${baseUrl}/auth/`)
+    const regResult = await registerPasskey(page, baseUrl, {
+      resetToken: deviceToken,
+      displayName: 'Max Age Test Device',
+    })
+
+    // Wait for session to be older than 1s
+    await page.waitForTimeout(2000)
+
+    const cookieName = getSessionCookieName()
+
+    // Make API call with max_age=1s (session is now > 1s old)
+    const response = await page.request.get(`${baseUrl}/auth/api/forward?max_age=1s`, {
+      headers: {
+        'Accept': 'application/json',
+        'Cookie': `${cookieName}=${regResult.session_token}`,
+      },
+    })
+
+    expect(response.status()).toBe(401)
+
+    const data = await response.json()
+    expect(data.auth).toBeDefined()
+    expect(data.auth.mode).toBe('reauth')
+
+    console.log(`✓ 401 response auth.mode: ${data.auth.mode}`)
+
+    // Save session for cleanup
+    saveSessionToken(regResult.session_token)
+  })
+})
diff --git a/e2e/tests/99-logout.spec.ts b/e2e/tests/99-logout.spec.ts
new file mode 100644
index 0000000..12db40b
--- /dev/null
+++ b/e2e/tests/99-logout.spec.ts
@@ -0,0 +1,33 @@
+import { test, expect } from './fixtures/virtual-authenticator'
+import {
+  logout,
+  getSessionCookieName,
+  getSavedSessionToken,
+} from './fixtures/passkey-helpers'
+
+/**
+ * Logout test - runs last to clean up the session.
+ * The "99-" prefix ensures this runs after all other tests.
+ */
+test.describe('Logout', () => {
+  const baseUrl = process.env.BASE_URL || 'http://localhost:4404'
+
+  test('should logout successfully', async ({ page }) => {
+    const sessionToken = getSavedSessionToken()
+    test.skip(!sessionToken, 'Requires saved session token')
+
+    await logout(page, baseUrl, sessionToken!)
+
+    // Session should no longer be valid
+    const cookieName = getSessionCookieName()
+    const response = await page.request.post(`${baseUrl}/auth/api/validate`, {
+      headers: {
+        'Cookie': `${cookieName}=${sessionToken}`,
+      },
+      failOnStatusCode: false,
+    })
+
+    expect(response.status()).toBe(401)
+    console.log(`✓ Logout successful, session invalidated`)
+  })
+})
diff --git a/e2e/tests/fixtures/passkey-helpers.ts b/e2e/tests/fixtures/passkey-helpers.ts
index 07981de..b2e7d6b 100644
--- a/e2e/tests/fixtures/passkey-helpers.ts
+++ b/e2e/tests/fixtures/passkey-helpers.ts
@@ -68,6 +68,22 @@ export function saveSessionToken(sessionToken: string): void {
   }
 }
 
+/**
+ * Clear the saved session token from the test state file.
+ * Call this after logout to prevent accidental reuse of invalidated sessions.
+ */
+export function clearSavedSessionToken(): void {
+  if (existsSync(stateFile)) {
+    try {
+      const state = JSON.parse(readFileSync(stateFile, 'utf-8'))
+      delete state.savedSessionToken
+      writeFileSync(stateFile, JSON.stringify(state, null, 2))
+    } catch {
+      // Ignore errors
+    }
+  }
+}
+
 /**
  * Get a saved session token from the test state file.
  */
@@ -83,6 +99,57 @@ export function getSavedSessionToken(): string | undefined {
   return undefined
 }
 
+/**
+ * Save device tokens to the test state file for use by other tests.
+ * These tokens allow tests to register their own passkeys.
+ */
+export function saveDeviceTokens(tokens: string[]): void {
+  if (existsSync(stateFile)) {
+    try {
+      const state = JSON.parse(readFileSync(stateFile, 'utf-8'))
+      state.deviceTokens = tokens
+      writeFileSync(stateFile, JSON.stringify(state, null, 2))
+    } catch {
+      // Ignore errors
+    }
+  }
+}
+
+/**
+ * Get and consume a device token from the pool.
+ * Returns undefined if no tokens are available.
+ */
+export function popDeviceToken(): string | undefined {
+  if (existsSync(stateFile)) {
+    try {
+      const state = JSON.parse(readFileSync(stateFile, 'utf-8'))
+      if (state.deviceTokens && state.deviceTokens.length > 0) {
+        const token = state.deviceTokens.pop()
+        writeFileSync(stateFile, JSON.stringify(state, null, 2))
+        return token
+      }
+    } catch {
+      return undefined
+    }
+  }
+  return undefined
+}
+
+/**
+ * Get the count of remaining device tokens.
+ */
+export function getDeviceTokenCount(): number {
+  if (existsSync(stateFile)) {
+    try {
+      const state = JSON.parse(readFileSync(stateFile, 'utf-8'))
+      return state.deviceTokens?.length || 0
+    } catch {
+      return 0
+    }
+  }
+  return 0
+}
+
 /**
  * Perform passkey registration via WebSocket.
  * This runs in the browser context using the virtual authenticator.
@@ -338,6 +405,7 @@ export async function getUserInfo(
 
 /**
  * Logout via the API.
+ * If the session being logged out matches the saved session token, clears it.
  */
 export async function logout(
   page: Page,
@@ -350,6 +418,11 @@ export async function logout(
       'Cookie': `${cookieName}=${sessionToken}`,
     },
   })
+  // Clear saved session token if it matches the one being logged out
+  const savedToken = getSavedSessionToken()
+  if (savedToken === sessionToken) {
+    clearSavedSessionToken()
+  }
 }
 
 /**
@@ -366,7 +439,13 @@ export async function createDeviceLink(
       'Cookie': `${cookieName}=${sessionToken}`,
     },
   })
+  if (!response.ok()) {
+    throw new Error(`Failed to create device link: ${response.status()} - ${await response.text()}`)
+  }
   const data = await response.json()
+  if (!data.url) {
+    throw new Error(`No URL in response: ${JSON.stringify(data)}`)
+  }
   // Extract token from URL (last path segment)
   const url = new URL(data.url)
   const token = url.pathname.split('/').pop() || ''
diff --git a/e2e/tests/global-setup.ts b/e2e/tests/global-setup.ts
index f9ddf33..128a12e 100644
--- a/e2e/tests/global-setup.ts
+++ b/e2e/tests/global-setup.ts
@@ -42,14 +42,12 @@ export default async function globalSetup() {
   const serverArgs = COLLECT_COVERAGE
     ? [
         'run', 'coverage', 'run', '--parallel-mode',
-        '-m', 'paskia.fastapi', 'serve', ':4401',
-        '--rp-id', 'localhost',
-        '--origin', 'http://localhost:4401'
+        '-m', 'paskia.fastapi', 'serve', 'localhost:4404',
+        '--rp-id', 'localhost'
       ]
     : [
-        'run', 'paskia', 'serve', ':4401',
-        '--rp-id', 'localhost',
-        '--origin', 'http://localhost:4401'
+        'run', 'paskia', 'serve', 'localhost:4404',
+        '--rp-id', 'localhost'
       ]
 
   // Start the server using Node's spawn
@@ -80,7 +78,7 @@ export default async function globalSetup() {
       process.stdout.write(text) // Echo to console
 
       // Look for the reset token URL in the output
-      // Format: https://localhost/auth/{token} or http://localhost:4401/auth/{token}
+      // Format: https://localhost/auth/{token} or http://localhost:4404/auth/{token}
       // where token is word.word.word.word.word (dot separated)
       const match = output.match(/https?:\/\/localhost(?::\d+)?\/auth\/([a-z]+(?:\.[a-z]+)+)/)
       if (match) {
@@ -117,7 +115,7 @@ export default async function globalSetup() {
 
   // Fetch session cookie name from server settings
   try {
-    const response = await fetch('http://localhost:4401/auth/api/settings')
+    const response = await fetch('http://localhost:4404/auth/api/settings')
     const settings = await response.json()
     state.sessionCookie = settings.session_cookie
     console.log(`  ✅ Session cookie name: ${state.sessionCookie}\n`)