Fix: Use ondatachannel instead of createDataChannel for answerer

CRITICAL BUG FIX: As the answerer, we should NOT create our own data channel.
The host (offerer) creates the channel, and we receive it via ondatachannel event.

This was causing messages to be sent on a different channel than the one
the host was listening to, so no messages were being received.

Changes:
- Remove pc.createDataChannel() call
- Add pc.ondatachannel event handler
- Wrap data channel setup in setupDataChannel() function
- Called when channel is received from host

test-connect.js

@@ -82,84 +82,88 @@ async function main() {
     console.log('\n3. Creating WebRTC peer connection...')
     const pc = new RTCPeerConnection(RTC_CONFIG)
 
-    // 4. Create data channel
+    // 4. Wait for data channel (we're the answerer, host creates the channel)
-    console.log('4. Creating data channel...')
+    console.log('4. Waiting for data channel from host...')
-    const dc = pc.createDataChannel('chat')
+    let dc = null
-
-    // Set up data channel handlers
     let identified = false
 
-    dc.onopen = () => {
+    // Function to setup data channel handlers
-      console.log('   ✓ Data channel opened!')
+    const setupDataChannel = (channel) => {
-      console.log(`   Data channel state: ${dc.readyState}`)
+      dc = channel
 
-      // Longer delay to ensure both sides are ready
+      dc.onopen = () => {
-      setTimeout(() => {
+        console.log('   ✓ Data channel opened!')
-        console.log(`   Data channel state before send: ${dc.readyState}`)
+        console.log(`   Data channel state: ${dc.readyState}`)
-        if (dc.readyState !== 'open') {
+
-          console.error(`   ❌ Data channel not open: ${dc.readyState}`)
+        // Longer delay to ensure both sides are ready
-          return
+        setTimeout(() => {
+          console.log(`   Data channel state before send: ${dc.readyState}`)
+          if (dc.readyState !== 'open') {
+            console.error(`   ❌ Data channel not open: ${dc.readyState}`)
+            return
+          }
+
+          // Send identify message (demo protocol)
+          console.log(`📤 Sending identify message...`)
+          const identifyMsg = JSON.stringify({
+            type: 'identify',
+            from: rondevu.getUsername()
+          })
+          console.log(`   Message:`, identifyMsg)
+          dc.send(identifyMsg)
+          console.log(`   ✓ Identify message sent, bufferedAmount: ${dc.bufferedAmount}`)
+        }, 500)
+      }
+
+      dc.onclose = () => {
+        console.log('   ❌ Data channel closed!')
+      }
+
+      dc.onmessage = (event) => {
+        console.log(`📥 RAW DATA:`, event.data)
+        try {
+          const msg = JSON.parse(event.data)
+          console.log(`📥 Parsed message:`, JSON.stringify(msg, null, 2))
+
+          if (msg.type === 'identify_ack' && !identified) {
+            identified = true
+            console.log(`✅ Connection acknowledged by @${msg.from}`)
+
+            // Now send the actual chat message
+            console.log(`📤 Sending chat message: "${MESSAGE}"`)
+            dc.send(JSON.stringify({
+              type: 'message',
+              text: MESSAGE
+            }))
+
+            // Keep connection open longer to see if we get a response
+            setTimeout(() => {
+              console.log('\n✅ Test completed successfully!')
+              dc.close()
+              pc.close()
+              process.exit(0)
+            }, 5000)
+          } else if (msg.type === 'message') {
+            console.log(`💬 @${msg.from || 'peer'}: ${msg.text}`)
+          } else {
+            console.log(`📥 Unknown message type: ${msg.type}`)
+          }
+        } catch (err) {
+          console.log(`📥 Parse error:`, err.message)
+          console.log(`📥 Raw data was:`, event.data)
         }
+      }
 
-        // Send identify message (demo protocol)
+      dc.onerror = (error) => {
-        console.log(`📤 Sending identify message...`)
+        console.error('❌ Data channel error:', error)
-        const identifyMsg = JSON.stringify({
+        process.exit(1)
-          type: 'identify',
-          from: rondevu.getUsername()
-        })
-        console.log(`   Message:`, identifyMsg)
-        dc.send(identifyMsg)
-        console.log(`   ✓ Identify message sent, bufferedAmount: ${dc.bufferedAmount}`)
-      }, 500)
-    }
-
-    dc.onclose = () => {
-      console.log('   ❌ Data channel closed!')
-    }
-
-    dc.onerror = (error) => {
-      console.error('❌ Data channel error:', error)
-      process.exit(1)
-    }
-
-    dc.onmessage = (event) => {
-      console.log(`📥 RAW DATA:`, event.data)
-      try {
-        const msg = JSON.parse(event.data)
-        console.log(`📥 Parsed message:`, JSON.stringify(msg, null, 2))
-
-        if (msg.type === 'identify_ack' && !identified) {
-          identified = true
-          console.log(`✅ Connection acknowledged by @${msg.from}`)
-
-          // Now send the actual chat message
-          console.log(`📤 Sending chat message: "${MESSAGE}"`)
-          dc.send(JSON.stringify({
-            type: 'message',
-            text: MESSAGE
-          }))
-
-          // Keep connection open longer to see if we get a response
-          setTimeout(() => {
-            console.log('\n✅ Test completed successfully!')
-            dc.close()
-            pc.close()
-            process.exit(0)
-          }, 5000)
-        } else if (msg.type === 'message') {
-          console.log(`💬 @${msg.from || 'peer'}: ${msg.text}`)
-        } else {
-          console.log(`📥 Unknown message type: ${msg.type}`)
-        }
-      } catch (err) {
-        console.log(`📥 Parse error:`, err.message)
-        console.log(`📥 Raw data was:`, event.data)
       }
     }
 
-    dc.onerror = (error) => {
+    // Receive data channel from host (we're the answerer)
-      console.error('❌ Data channel error:', error)
+    pc.ondatachannel = (event) => {
-      process.exit(1)
+      console.log('   ✓ Data channel received from host!')
+      setupDataChannel(event.channel)
     }
 
     // 5. Set up ICE candidate exchange FIRST