Fix GStreamer signaling protocol handling

- Fix producer list parsing (array not object)
- Consumer acts as answerer (GStreamer webrtcsink sends offer)
- Remove STUN server for LAN connections
- Better error handling in peer message handling

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

index.html

@@ -277,20 +277,21 @@
             const container = document.getElementById('producerList');
             container.innerHTML = '';
 
-            if (!producers || Object.keys(producers).length === 0) {
+            // GStreamer returns array of {id, meta} objects
+            if (!producers || !Array.isArray(producers) || producers.length === 0) {
                 container.innerHTML = '<em style="color: #666;">No producers available</em>';
                 return;
             }
 
-            for (const [peerId, meta] of Object.entries(producers)) {
+            for (const producer of producers) {
                 const div = document.createElement('div');
                 div.className = 'producer-item';
-                div.innerHTML = `<strong>${meta.name || 'Unknown'}</strong><br><small>${peerId}</small>`;
-                div.onclick = () => selectProducer(peerId, div);
+                div.innerHTML = `<strong>${producer.meta?.name || 'Unknown'}</strong><br><small>${producer.id}</small>`;
+                div.onclick = () => selectProducer(producer.id, div);
                 container.appendChild(div);
             }
 
-            log(`Found ${Object.keys(producers).length} producer(s)`, 'success');
+            log(`Found ${producers.length} producer(s)`, 'success');
         }
 
         function selectProducer(peerId, element) {
@@ -311,8 +312,9 @@
             log('Creating peer connection...');
             updateWebrtcStatus('connecting');
 
+            // LAN connection - no STUN needed for local network
             const config = {
-                iceServers: [{ urls: 'stun:stun.l.google.com:19302' }]
+                iceServers: []
             };
 
             peerConnection = new RTCPeerConnection(config);
@@ -341,7 +343,8 @@
 
             peerConnection.oniceconnectionstatechange = () => {
                 log(`ICE connection state: ${peerConnection.iceConnectionState}`);
-                if (peerConnection.iceConnectionState === 'connected') {
+                if (peerConnection.iceConnectionState === 'connected' ||
+                    peerConnection.iceConnectionState === 'completed') {
                     updateWebrtcStatus('connected');
                     document.getElementById('stopStreamBtn').disabled = false;
                     document.getElementById('sendPoseBtn').disabled = false;
@@ -358,54 +361,50 @@
                 setupDataChannel(dataChannel);
             };
 
-            // Add transceivers for receiving
-            peerConnection.addTransceiver('video', { direction: 'recvonly' });
-            peerConnection.addTransceiver('audio', { direction: 'recvonly' });
-
-            // Create and send offer
-            try {
-                const offer = await peerConnection.createOffer();
-                await peerConnection.setLocalDescription(offer);
-
-                log('Sending SDP offer to signaling server...');
-                signalingWs.send(JSON.stringify({
-                    type: 'startSession',
-                    peerId: selectedProducerId
-                }));
-
-                // Send SDP
-                signalingWs.send(JSON.stringify({
-                    type: 'peer',
-                    sessionId: selectedProducerId,
-                    sdp: {
-                        type: 'offer',
-                        sdp: offer.sdp
-                    }
-                }));
-            } catch (e) {
-                log(`Failed to create offer: ${e.message}`, 'error');
-            }
+            // GStreamer webrtcsink is the offerer, we are the answerer
+            // Just request to start a session, then wait for SDP offer
+            log('Requesting session with producer...');
+            signalingWs.send(JSON.stringify({
+                type: 'startSession',
+                peerId: selectedProducerId
+            }));
+            // SDP offer will arrive via handlePeerMessage
         }
 
         async function handlePeerMessage(msg) {
-            if (msg.sdp) {
-                log(`Received SDP ${msg.sdp.type}`);
-                await peerConnection.setRemoteDescription(new RTCSessionDescription(msg.sdp));
+            if (!peerConnection) {
+                log('No peer connection, ignoring message', 'error');
+                return;
+            }
 
-                if (msg.sdp.type === 'offer') {
-                    const answer = await peerConnection.createAnswer();
-                    await peerConnection.setLocalDescription(answer);
-                    signalingWs.send(JSON.stringify({
-                        type: 'peer',
-                        sessionId: selectedProducerId,
-                        sdp: { type: 'answer', sdp: answer.sdp }
-                    }));
+            try {
+                if (msg.sdp) {
+                    log(`Received SDP ${msg.sdp.type}`);
+                    await peerConnection.setRemoteDescription(new RTCSessionDescription(msg.sdp));
+
+                    if (msg.sdp.type === 'offer') {
+                        log('Creating answer...');
+                        const answer = await peerConnection.createAnswer();
+                        await peerConnection.setLocalDescription(answer);
+                        log('Sending SDP answer');
+                        signalingWs.send(JSON.stringify({
+                            type: 'peer',
+                            sessionId: selectedProducerId,
+                            sdp: { type: 'answer', sdp: answer.sdp }
+                        }));
+                    }
                 }
-            }
 
-            if (msg.ice) {
-                log('Received ICE candidate');
-                await peerConnection.addIceCandidate(new RTCIceCandidate(msg.ice));
+                if (msg.ice) {
+                    log('Received ICE candidate');
+                    try {
+                        await peerConnection.addIceCandidate(new RTCIceCandidate(msg.ice));
+                    } catch (e) {
+                        log(`Failed to add ICE candidate: ${e.message}`, 'error');
+                    }
+                }
+            } catch (e) {
+                log(`Error handling peer message: ${e.message}`, 'error');
             }
         }