fix: request call permissions and simplify CTA

components/meeting/PreJoinScreen.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useEffect, useRef, useState } from "react";
+import { useCallback, useEffect, useRef, useState } from "react";
 import { createLocalTracks, Track, type LocalTrack } from "livekit-client";
 
 export function PreJoinScreen({ onContinue }: { onContinue: (tracks: LocalTrack[]) => void }) {
@@ -9,8 +9,10 @@ export function PreJoinScreen({ onContinue }: { onContinue: (tracks: LocalTrack[
   const [micOn, setMicOn] = useState(true);
   const [cameraOn, setCameraOn] = useState(true);
   const [speakerTested, setSpeakerTested] = useState(false);
+  const [requestingDevices, setRequestingDevices] = useState(false);
   const videoRef = useRef<HTMLVideoElement>(null);
   const handedOffRef = useRef(false);
+  const initialDeviceRequestRef = useRef(false);
 
   const videoTrack = tracks.find((track) => track.kind === Track.Kind.Video);
   const audioTrack = tracks.find((track) => track.kind === Track.Kind.Audio);
@@ -30,9 +32,11 @@ export function PreJoinScreen({ onContinue }: { onContinue: (tracks: LocalTrack[
     };
   }, [tracks]);
 
-  async function requestDevices() {
+  const requestDevices = useCallback(async () => {
+    if (requestingDevices) return;
     tracks.forEach((track) => track.stop());
     setError(null);
+    setRequestingDevices(true);
     try {
       const nextTracks = await createLocalTracks({ audio: true, video: true });
       setTracks(nextTracks);
@@ -40,8 +44,16 @@ export function PreJoinScreen({ onContinue }: { onContinue: (tracks: LocalTrack[
       setCameraOn(true);
     } catch {
       setError("Kamera oder Mikrofon konnten nicht freigegeben werden. Du kannst trotzdem ohne sie beitreten.");
+    } finally {
+      setRequestingDevices(false);
     }
-  }
+  }, [requestingDevices, tracks]);
+
+  useEffect(() => {
+    if (initialDeviceRequestRef.current) return;
+    initialDeviceRequestRef.current = true;
+    void requestDevices();
+  }, [requestDevices]);
 
   async function toggleMic() {
     if (!audioTrack) return;
@@ -104,9 +116,10 @@ export function PreJoinScreen({ onContinue }: { onContinue: (tracks: LocalTrack[
             <button
               type="button"
               onClick={requestDevices}
-              className="rounded-full bg-white px-5 py-3 text-sm font-medium text-neutral-900 hover:bg-white/85"
+              disabled={requestingDevices}
+              className="rounded-full bg-white px-5 py-3 text-sm font-medium text-neutral-900 hover:bg-white/85 disabled:cursor-wait disabled:opacity-75"
             >
-              {tracks.length > 0 ? "Geräte erneut prüfen" : "Kamera & Mikrofon aktivieren"}
+              {requestingDevices ? "Berechtigung wird angefragt …" : tracks.length > 0 ? "Geräte erneut prüfen" : "Kamera & Mikrofon aktivieren"}
             </button>
             <div className="grid grid-cols-2 gap-3">
               <button type="button" onClick={() => void toggleMic()} disabled={!audioTrack} className="rounded-2xl bg-white/10 px-4 py-3 text-xs hover:bg-white/15 disabled:opacity-40">