diff --git a/frontend/auth/App.vue b/frontend/auth/App.vue
index ed0591d..1ebb732 100644
--- a/frontend/auth/App.vue
+++ b/frontend/auth/App.vue
@@ -13,8 +13,7 @@
 <script setup>
 import { computed, onMounted, onUnmounted, ref } from 'vue'
 import { useAuthStore } from '@/stores/auth'
-import { apiJson, SessionValidator, createAuthIframe, removeAuthIframe } from 'paskia'
-import { getAuthIframeUrl } from '@/utils/api'
+import { apiJson, SessionValidator } from 'paskia'
 import { updateThemeFromSession } from '@/utils/theme'
 import StatusMessage from '@/components/StatusMessage.vue'
 import ProfileView from '@/components/ProfileView.vue'
@@ -49,19 +48,29 @@ const isHostMode = computed(() => {
   return currentHost !== configuredHost
 })
 
-function terminateSession() {
+function onSessionLost(e) {
   store.userInfo = null
-  viewState.value = 'terminal'
+  store.ctx = null
+  if (e?.name === 'AuthCancelledError') {
+    viewState.value = 'terminal'
+  } else {
+    store.showMessage(e?.message || 'Session lost', 'error', 5000)
+    viewState.value = 'terminal'
+  }
 }
 
 const userUuidGetter = () => store.ctx?.user.uuid
-const sessionValidator = new SessionValidator(userUuidGetter, terminateSession)
+const sessionValidator = new SessionValidator(userUuidGetter, onSessionLost)
 
 onMounted(() => sessionValidator.start())
 onUnmounted(() => sessionValidator.stop())
 
 async function loadUserInfo() {
+  viewState.value = 'loading'
+  loadingMessage.value = 'Loading...'
   try {
+    // apiJson handles 401/403 with auth.iframe automatically:
+    // shows overlay iframe, waits for auth, retries the request.
     const [validateData, userInfoData] = await Promise.all([
       apiJson('/auth/api/validate', { method: 'POST' }),
       apiJson('/auth/api/user-info', { method: 'GET' })
@@ -73,67 +82,15 @@ async function loadUserInfo() {
     if (store.userInfo.user.uuid !== store.ctx.user.uuid) {
       console.error('User UUID mismatch between user-info and validate responses')
       window.location.reload()
-      return false
+      return
     }
     viewState.value = 'profile'
-    return true
-  } catch {
-    store.userInfo = null
-    store.ctx = null
-    return false
-  }
-}
-
-async function showAuthIframe() {
-  const url = await getAuthIframeUrl('login')
-  createAuthIframe(url)
-  loadingMessage.value = 'Authentication required...'
-}
-
-function handleAuthMessage(event) {
-  const data = event.data
-  if (!data?.type) return
-
-  switch (data.type) {
-    case 'auth-success':
-      // Authentication successful - reload user info
-      removeAuthIframe()
-      viewState.value = 'loading'
-      loadingMessage.value = 'Loading user profile...'
-      loadUserInfo()
-      break
-
-    case 'auth-error':
-      // Authentication failed - keep iframe open so user can retry
-      if (data.cancelled) {
-        console.log('Authentication cancelled by user')
-      } else {
-        store.showMessage(data.message || 'Authentication failed', 'error', 5000)
-      }
-      break
-
-    case 'auth-cancelled':
-      // Legacy support - treat as auth-error with cancelled flag
-      console.log('Authentication cancelled')
-      break
-
-    case 'auth-back':
-      // User clicked Back - show terminal state
-      removeAuthIframe()
-      terminateSession()
-      break
-
-    case 'auth-close-request':
-      // Legacy support - treat as back
-      removeAuthIframe()
-      break
+  } catch (e) {
+    onSessionLost(e)
   }
 }
 
 onMounted(async () => {
-  // Listen for postMessage from auth iframe
-  window.addEventListener('message', handleAuthMessage)
-
   // Load settings
   await store.loadSettings()
 
@@ -147,17 +104,7 @@ onMounted(async () => {
     document.title = inHostMode ? `${rpName} · Account summary` : rpName
   }
 
-  // Try to load user info
-  const success = await loadUserInfo()
-
-  if (!success) {
-    // Need authentication - show login iframe
-    showAuthIframe()
-  }
-})
-
-onUnmounted(() => {
-  window.removeEventListener('message', handleAuthMessage)
-  removeAuthIframe()
+  // Load user info (apiJson handles auth iframe if needed)
+  await loadUserInfo()
 })
 </script>
diff --git a/frontend/src/components/RegistrationLinkModal.vue b/frontend/src/components/RegistrationLinkModal.vue
index d4a5fbe..adb0ec8 100644
--- a/frontend/src/components/RegistrationLinkModal.vue
+++ b/frontend/src/components/RegistrationLinkModal.vue
@@ -37,7 +37,7 @@
 <script setup>
 import { ref, computed, onMounted, onUnmounted, nextTick } from 'vue'
 import QRCodeDisplay from '@/components/QRCodeDisplay.vue'
-import { apiJson, holdGlobalBackdrop, releaseGlobalBackdrop } from 'paskia'
+import { apiJson, AuthCancelledError, holdGlobalBackdrop, releaseGlobalBackdrop } from 'paskia'
 import { formatDate } from '@/utils/helpers'
 import { getDirection } from '@/utils/keynav'
 import { useAuthStore } from '@/stores/auth'
@@ -90,7 +90,9 @@ async function generateLink() {
       emit('close')
     }
   } catch (e) {
-    authStore.showMessage(e.message || 'Failed to generate link', 'error')
+    if (!(e instanceof AuthCancelledError)) {
+      authStore.showMessage(e.message || 'Failed to generate link', 'error')
+    }
     emit('close')
   }
 }
diff --git a/frontend/src/utils/api.js b/frontend/src/utils/api.js
deleted file mode 100644
index 4743e27..0000000
--- a/frontend/src/utils/api.js
+++ /dev/null
@@ -1,32 +0,0 @@
-// Cache for auth iframe URL by mode
-const authIframeUrlCache = {}
-
-/**
- * Get the auth iframe URL for a given mode.
- * Fetches from /auth/api/forward which returns URL in the auth.iframe field.
- * Results are cached per mode.
- * @param {string} mode - The auth mode ('login', 'reauth', 'forbidden')
- * @returns {Promise<string>} - The URL for the iframe
- */
-export async function getAuthIframeUrl(mode = 'login') {
-  if (authIframeUrlCache[mode]) {
-    return authIframeUrlCache[mode]
-  }
-
-  // Fetch from forward endpoint - it returns URL in auth.iframe on 401/403
-  const response = await fetch('/auth/api/forward')
-  if (response.status === 401 || response.status === 403) {
-    const data = await response.json()
-    if (data.auth?.iframe) {
-      // The iframe field now contains a URL with hash fragment
-      // If mode differs, update the hash param
-      let url = data.auth.iframe
-      if (mode !== data.auth.mode) {
-        url = url.replace(/mode=[^&]*/, `mode=${mode}`)
-      }
-      authIframeUrlCache[mode] = url
-      return url
-    }
-  }
-  throw new Error('Unable to fetch auth iframe URL')
-}
diff --git a/paskia-js/src/index.ts b/paskia-js/src/index.ts
index 2b66002..65ece2b 100644
--- a/paskia-js/src/index.ts
+++ b/paskia-js/src/index.ts
@@ -18,8 +18,6 @@ export {
   isAuthIframeOpen,
   hideAuthIframe,
   showAuthIframe,
-  createAuthIframe,
-  removeAuthIframe,
 } from './overlay'
 
 export { SessionValidator } from './validate'
diff --git a/paskia/fastapi/api.py b/paskia/fastapi/api.py
index 7519c89..e14cb6c 100644
--- a/paskia/fastapi/api.py
+++ b/paskia/fastapi/api.py
@@ -214,7 +214,12 @@ async def api_user_info(
         )
     ctx = db.data().session_ctx(auth, request.headers.get("host"))
     if not ctx:
-        raise HTTPException(401, "Session expired")
+        raise authz.AuthException(
+            status_code=401,
+            detail="Session expired",
+            mode="login",
+            clear_session=True,
+        )
 
     return MsgspecResponse(
         await userinfo.build_user_info(