diff --git a/app.js b/app.js
index 64b61d3..2e8ba22 100644
--- a/app.js
+++ b/app.js
@@ -12,6 +12,27 @@
     document.body.classList.add('debug-mode');
   }
 
+  document.querySelectorAll('.raw-data').forEach(el => {
+    el.style.cursor = 'pointer';
+    el.title = 'Klicken zum Kopieren';
+    el.addEventListener('click', async () => {
+      try {
+        await navigator.clipboard.writeText(el.textContent);
+        const orig = el.textContent;
+        el.textContent = 'Kopiert!';
+        setTimeout(() => { el.textContent = orig; }, 1200);
+      } catch (e) {
+        const sel = window.getSelection();
+        const range = document.createRange();
+        range.selectNodeContents(el);
+        sel.removeAllRanges();
+        sel.addRange(range);
+        document.execCommand('copy');
+        sel.removeAllRanges();
+      }
+    });
+  });
+
   /* ─── Screen routing ─── */
   function show(name) {
     ['start','host','join','game','result'].forEach(s =>
@@ -43,7 +64,8 @@
     const c = $(containerId);
     if (!c) return;
     c.innerHTML = '';
-    qrHost = new QRCode(c, { text: data, width: 200, height: 200, correctLevel: QRCode.CorrectLevel.L });
+    const size = Math.min(window.innerWidth - 64, 360);
+    qrHost = new QRCode(c, { text: data, width: size, height: size, correctLevel: QRCode.CorrectLevel.L });
   }
 
   /* ─── Camera ─── */
@@ -52,14 +74,22 @@
 
   async function camStart(videoId) {
     await camStop();
-    camStream = await navigator.mediaDevices.getUserMedia({
-      video: { facingMode: 'environment', width: { ideal: 320 }, height: { ideal: 240 } }
-    });
+    try {
+      camStream = await navigator.mediaDevices.getUserMedia({
+        video: { facingMode: { ideal: 'environment' }, width: { ideal: 1920 }, height: { ideal: 1080 } }
+      });
+    } catch (_) {
+      camStream = await navigator.mediaDevices.getUserMedia({ video: true });
+    }
     const v = $(videoId);
     v.srcObject = camStream;
     v.setAttribute('playsinline', '');
     v.classList.add('active');
     await v.play();
+    try {
+      const track = camStream.getVideoTracks()[0];
+      if (track) track.applyConstraints({ advanced: [{ focusMode: 'continuous' }] });
+    } catch (_) {}
     return v;
   }
 
@@ -71,13 +101,16 @@
   function camScan(videoId, canvasId, callback) {
     const v = $(videoId);
     const c = $(canvasId);
-    const ctx = c.getContext('2d');
-    camRaf = requestAnimationFrame(function tick() {
+    const ctx = c.getContext('2d', { willReadFrequently: true });
+    let lastScan = 0;
+    camRaf = requestAnimationFrame(function tick(now) {
       if (!v.videoWidth) { camRaf = requestAnimationFrame(tick); return; }
+      if (now - lastScan < 100) { camRaf = requestAnimationFrame(tick); return; }
+      lastScan = now;
       c.width = v.videoWidth; c.height = v.videoHeight;
       ctx.drawImage(v, 0, 0);
       const img = ctx.getImageData(0, 0, c.width, c.height);
-      const code = jsQR(img.data, img.width, img.height);
+      const code = jsQR(img.data, img.width, img.height, { inversionAttempts: 'dontInvert' });
       if (code && code.data) {
         try {
           const p = JSON.parse(code.data);
@@ -244,6 +277,8 @@
     mesh.onanswerready = answerData => {
       $('join-answer-section').hidden = false;
       showQR('qr-answer', answerData);
+      const raw = $('answer-raw');
+      if (raw) raw.textContent = answerData;
       $('join-scan-status').textContent = 'Antwort-QR dem Host zeigen';
       camStop();
     };
diff --git a/index.html b/index.html
index d2c294a..ffe4285 100644
--- a/index.html
+++ b/index.html
@@ -69,6 +69,10 @@
         <p>Antwort-QR für den Host:</p>
         <div id="qr-answer"></div>
         <p class="hint">Zeige diesen QR-Code dem Host</p>
+        <details class="debug-helper debug-only" style="margin-top:8px">
+          <summary>QR-Rohdaten</summary>
+          <pre id="answer-raw" class="raw-data"></pre>
+        </details>
       </div>
       <ul id="join-player-list" class="player-list"></ul>
     </div>
@@ -121,9 +125,9 @@
     </div>
   </section>
 
-  <script src="https://unpkg.com/simple-peer@9.11.1/simplepeer.min.js"></script>
-  <script src="https://cdnjs.cloudflare.com/ajax/libs/qrcodejs/1.0.0/qrcode.min.js"></script>
-  <script src="https://cdn.jsdelivr.net/npm/jsqr@1.4.0/dist/jsQR.js"></script>
+  <script src="vendor/simplepeer.min.js"></script>
+  <script src="vendor/qrcode.min.js"></script>
+  <script src="vendor/jsQR.js"></script>
   <script src="crypto.js"></script>
   <script src="p2p.js"></script>
   <script src="protocol.js"></script>