diff --git a/pages/registrieren.vue b/pages/registrieren.vue
index d651bcf..b4a1f66 100644
--- a/pages/registrieren.vue
+++ b/pages/registrieren.vue
@@ -630,6 +630,18 @@ const handleRegisterWithPasskey = async () => {
       })
       
       // Neue API-Struktur: { optionsJSON: options }
+      // WICHTIG: Bei Cross-Device wird der QR-Code automatisch generiert
+      // Das Smartphone scannt den QR-Code und öffnet die Website
+      // Dann ruft das Smartphone startRegistration auf, um die Credential zu erstellen
+      // Die Credential-Response wird dann an den Desktop-Browser zurückgesendet
+      console.log('[DEBUG] About to call startRegistration - this will trigger QR code generation for Cross-Device')
+      console.log('[DEBUG] If using Cross-Device:')
+      console.log('[DEBUG] 1. QR-Code wird angezeigt')
+      console.log('[DEBUG] 2. Smartphone scannt QR-Code')
+      console.log('[DEBUG] 3. Smartphone öffnet:', window.location.origin)
+      console.log('[DEBUG] 4. Smartphone muss startRegistration aufrufen können')
+      console.log('[DEBUG] 5. Smartphone sendet Credential-Response an:', window.location.origin + '/api/auth/register-passkey')
+      
       credential = await mod.startRegistration({ optionsJSON: pre.options })
       
       clearTimeout(timeoutWarning)
@@ -640,7 +652,8 @@ const handleRegisterWithPasskey = async () => {
         credentialId: credential?.id,
         responseType: credential?.response?.constructor?.name,
         transports: credential?.transports,
-        durationSeconds: Math.round(webauthnDuration / 1000)
+        durationSeconds: Math.round(webauthnDuration / 1000),
+        note: 'Wenn Cross-Device verwendet wurde, sollte die Credential-Response vom Smartphone kommen'
       })
     } catch (webauthnError) {
       const webauthnDuration = Date.now() - webauthnStart
diff --git a/server/api/auth/register-passkey-options.options.js b/server/api/auth/register-passkey-options.options.js
index 8f7615a..b3bd46a 100644
--- a/server/api/auth/register-passkey-options.options.js
+++ b/server/api/auth/register-passkey-options.options.js
@@ -4,10 +4,17 @@ export default defineEventHandler(async (event) => {
   const requestOrigin = getHeader(event, 'origin')
   const { origin: webauthnOrigin } = getWebAuthnConfig()
   
-  console.log('[DEBUG] OPTIONS preflight request received', {
-    origin: requestOrigin,
+  const userAgent = getHeader(event, 'user-agent')
+  const ip = getHeader(event, 'x-forwarded-for') || getHeader(event, 'x-real-ip') || 'unknown'
+  
+  console.log('[DEBUG] ===== OPTIONS preflight for /api/auth/register-passkey-options =====')
+  console.log('[DEBUG] OPTIONS Request Details:', {
+    origin: requestOrigin || 'none',
     webauthnOrigin,
-    timestamp: new Date().toISOString()
+    userAgent: userAgent?.substring(0, 100) || 'none',
+    ip,
+    timestamp: new Date().toISOString(),
+    note: 'OPTIONS Preflight für Passkey Registration Options'
   })
 
   // CORS-Header für Cross-Device Authentication
diff --git a/server/api/auth/register-passkey-options/[registrationId].get.js b/server/api/auth/register-passkey-options/[registrationId].get.js
new file mode 100644
index 0000000..85efa4f
--- /dev/null
+++ b/server/api/auth/register-passkey-options/[registrationId].get.js
@@ -0,0 +1,76 @@
+import { getPreRegistration } from '../../../utils/webauthn-challenges.js'
+import { generateRegistrationOptions } from '@simplewebauthn/server'
+import { getWebAuthnConfig } from '../../../utils/webauthn-config.js'
+
+export default defineEventHandler(async (event) => {
+  const registrationId = getRouterParam(event, 'registrationId')
+  const requestOrigin = getHeader(event, 'origin')
+  const userAgent = getHeader(event, 'user-agent')
+  
+  console.log('[DEBUG] ===== GET register-passkey-options/[registrationId] =====')
+  console.log('[DEBUG] Request Details:', {
+    registrationId,
+    origin: requestOrigin,
+    userAgent: userAgent?.substring(0, 100),
+    timestamp: new Date().toISOString(),
+    method: getMethod(event),
+    note: 'Dieser Endpoint wird vom Smartphone aufgerufen, um die Options für Cross-Device zu erhalten'
+  })
+
+  if (!registrationId) {
+    throw createError({ statusCode: 400, message: 'registrationId ist erforderlich' })
+  }
+
+  // Hole Pre-Registration-Daten
+  const pre = getPreRegistration(registrationId)
+  if (!pre) {
+    console.error('[DEBUG] Pre-registration not found', { registrationId })
+    throw createError({ statusCode: 404, message: 'Registrierungs-Session nicht gefunden oder abgelaufen' })
+  }
+
+  const { challenge, userId, name, email } = pre
+  console.log('[DEBUG] Pre-registration found', {
+    userId,
+    email: email?.substring(0, 10) + '...',
+    hasChallenge: !!challenge
+  })
+
+  const { rpId, rpName, origin: webauthnOrigin } = getWebAuthnConfig()
+
+  // Generiere Options neu (mit der gespeicherten Challenge)
+  const options = await generateRegistrationOptions({
+    rpName,
+    rpID: rpId,
+    userID: new TextEncoder().encode(String(userId)),
+    userName: email,
+    userDisplayName: name,
+    attestationType: 'none',
+    authenticatorSelection: {
+      residentKey: 'preferred',
+      userVerification: 'preferred'
+    },
+    timeout: 300000,
+    challenge: challenge // Verwende die gespeicherte Challenge
+  })
+
+  console.log('[DEBUG] Options regenerated for Cross-Device', {
+    hasChallenge: !!options.challenge,
+    challengeMatches: options.challenge === challenge,
+    rpId: options.rp?.id
+  })
+
+  // CORS-Header für Cross-Device
+  const allowedOrigin = requestOrigin || webauthnOrigin
+  if (allowedOrigin) {
+    setHeader(event, 'Access-Control-Allow-Origin', allowedOrigin)
+    setHeader(event, 'Access-Control-Allow-Credentials', 'true')
+    setHeader(event, 'Access-Control-Allow-Methods', 'GET, OPTIONS')
+    setHeader(event, 'Access-Control-Allow-Headers', 'Content-Type, Authorization, Origin, X-Requested-With')
+  }
+
+  return {
+    success: true,
+    registrationId,
+    options
+  }
+})
diff --git a/server/api/auth/register-passkey.options.js b/server/api/auth/register-passkey.options.js
index b394186..6a1cfbd 100644
--- a/server/api/auth/register-passkey.options.js
+++ b/server/api/auth/register-passkey.options.js
@@ -4,10 +4,17 @@ export default defineEventHandler(async (event) => {
   const requestOrigin = getHeader(event, 'origin')
   const { origin: webauthnOrigin } = getWebAuthnConfig()
   
-  console.log('[DEBUG] OPTIONS preflight request received (register-passkey)', {
-    origin: requestOrigin,
+  const userAgent = getHeader(event, 'user-agent')
+  const ip = getHeader(event, 'x-forwarded-for') || getHeader(event, 'x-real-ip') || 'unknown'
+  
+  console.log('[DEBUG] ===== OPTIONS preflight for /api/auth/register-passkey =====')
+  console.log('[DEBUG] OPTIONS Request Details:', {
+    origin: requestOrigin || 'none',
     webauthnOrigin,
-    timestamp: new Date().toISOString()
+    userAgent: userAgent?.substring(0, 100) || 'none',
+    ip,
+    timestamp: new Date().toISOString(),
+    note: 'OPTIONS Preflight für Cross-Device Passkey - Wenn dieser Request vom Smartphone kommt, sollte der User-Agent Mobile/Android/iPhone enthalten'
   })
 
   // CORS-Header für Cross-Device Authentication
diff --git a/server/api/auth/register-passkey.post.js b/server/api/auth/register-passkey.post.js
index 5212230..2a2b8fc 100644
--- a/server/api/auth/register-passkey.post.js
+++ b/server/api/auth/register-passkey.post.js
@@ -15,16 +15,27 @@ export default defineEventHandler(async (event) => {
   const userAgent = getHeader(event, 'user-agent')
   const { origin: webauthnOrigin } = getWebAuthnConfig()
   
-  console.log('[DEBUG] ===== register-passkey request received =====')
+  console.log('')
+  console.log('='.repeat(80))
+  console.log('[DEBUG] 🔑 ===== PASSKEY REGISTRATION REQUEST RECEIVED =====')
+  console.log('='.repeat(80))
   console.log('[DEBUG] Request Details:', {
-    origin: requestOrigin,
+    origin: requestOrigin || 'none',
     webauthnOrigin,
-    userAgent: userAgent?.substring(0, 150),
+    userAgent: userAgent?.substring(0, 150) || 'none',
     timestamp: new Date().toISOString(),
     method: getMethod(event),
     ip: getClientIp(event),
-    note: 'Dieser Request sollte vom Smartphone kommen, wenn der QR-Code gescannt wurde'
+    url: getRequestURL(event).href,
+    path: getRequestURL(event).pathname
   })
+  console.log('[DEBUG] ⚠️ WICHTIG: Dieser Request sollte vom Smartphone kommen, wenn der QR-Code gescannt wurde')
+  console.log('[DEBUG] ⚠️ Wenn dieser Request NICHT im Log erscheint, bedeutet das:')
+  console.log('[DEBUG]   1. Das Smartphone konnte die Website nicht erreichen')
+  console.log('[DEBUG]   2. Oder startRegistration auf dem Smartphone ist fehlgeschlagen')
+  console.log('[DEBUG]   3. Oder die Credential-Response wurde nicht gesendet')
+  console.log('='.repeat(80))
+  console.log('')
   console.log('[DEBUG] User-Agent Analysis:', {
     isMobile: /Mobile|Android|iPhone|iPad/i.test(userAgent || ''),
     isChrome: /Chrome/i.test(userAgent || ''),
diff --git a/server/middleware/log-requests.js b/server/middleware/log-requests.js
new file mode 100644
index 0000000..8f0d715
--- /dev/null
+++ b/server/middleware/log-requests.js
@@ -0,0 +1,41 @@
+/**
+ * Globales Request-Logging für Debugging
+ * Loggt alle Requests, besonders Passkey-relevante Endpoints
+ */
+
+export default defineEventHandler((event) => {
+  const url = getRequestURL(event)
+  const method = getMethod(event)
+  const path = url.pathname
+  const origin = getHeader(event, 'origin')
+  const userAgent = getHeader(event, 'user-agent')
+  const ip = getHeader(event, 'x-forwarded-for') || getHeader(event, 'x-real-ip') || 'unknown'
+  
+  // Logge nur Passkey-relevante Endpoints (um Logs nicht zu überfluten)
+  const passkeyEndpoints = [
+    '/api/auth/register-passkey',
+    '/api/auth/register-passkey-options',
+    '/api/auth/passkeys/registration-options',
+    '/api/auth/passkeys/register',
+    '/api/auth/passkeys/authentication-options',
+    '/api/auth/passkeys/login',
+    '/api/auth/passkeys/recovery'
+  ]
+  
+  const isPasskeyEndpoint = passkeyEndpoints.some(ep => path.startsWith(ep))
+  
+  if (isPasskeyEndpoint) {
+    const timestamp = new Date().toISOString()
+    console.log(`[REQUEST] ${timestamp} ${method} ${path}`)
+    console.log(`[REQUEST] Origin: ${origin || 'none'}`)
+    console.log(`[REQUEST] IP: ${ip}`)
+    console.log(`[REQUEST] User-Agent: ${userAgent?.substring(0, 100) || 'none'}`)
+    
+    // Spezielle Logs für Cross-Device
+    if (path.includes('register-passkey')) {
+      console.log(`[REQUEST] 🔑 PASSKEY REQUEST - ${method} ${path}`)
+      console.log(`[REQUEST] ⚠️ Wenn dieser Request vom Smartphone kommt, sollte der User-Agent Mobile/Android/iPhone enthalten`)
+      console.log(`[REQUEST] ⚠️ Wenn dieser Request NICHT kommt, erreicht das Smartphone den Server nicht`)
+    }
+  }
+})
diff --git a/server/utils/webauthn-challenges.js b/server/utils/webauthn-challenges.js
index 9ec4b2d..4455b4f 100644
--- a/server/utils/webauthn-challenges.js
+++ b/server/utils/webauthn-challenges.js
@@ -59,4 +59,12 @@ export function consumePreRegistration(registrationId) {
   return v.payload || null
 }
 
+export function getPreRegistration(registrationId) {
+  cleanup(preRegChallenges)
+  const key = String(registrationId)
+  const v = preRegChallenges.get(key)
+  if (!v) return null
+  return v.payload || null
+}
+