fix: clamp reconnect backoff delay and add observability logging

Author: siddimore

engine.go

@@ -486,6 +486,7 @@ func (e *RTCEngine) createSubscriberPCLocked(configuration webrtc.Configuration)
 		} else if c.Label() == lossyDataChannelName {
 			e.lossyDCSub = c
 		} else {
+			e.log.Warnw("received unknown data channel label, ignoring", nil, "label", c.Label())
 			return
 		}
 		c.OnMessage(e.handleDataPacket)
@@ -626,6 +627,7 @@ func (e *RTCEngine) UnregisterTrackPublishedListener(cid string) {
 func (e *RTCEngine) handleDataPacket(msg webrtc.DataChannelMessage) {
 	packet, err := e.readDataPacket(msg)
 	if err != nil {
+		e.log.Warnw("failed to parse data packet", err, "isString", msg.IsString)
 		return
 	}
 	identity := packet.ParticipantIdentity
@@ -733,10 +735,10 @@ func (e *RTCEngine) handleDisconnect(fullReconnect bool) {
 				}
 			}
 
-			delay := time.Duration(reconnectCount*reconnectCount) * initialReconnectInterval
-			if delay > maxReconnectInterval {
-				break
-			}
+			// Quadratic backoff: delay grows as reconnectCount² × initialReconnectInterval.
+			// Clamped to maxReconnectInterval so a future increase to maxReconnectCount
+			// cannot produce unbounded delays or skip the final OnDisconnected call.
+			delay := min(time.Duration(reconnectCount*reconnectCount)*initialReconnectInterval, maxReconnectInterval)
 			if reconnectCount < maxReconnectCount-1 {
 				time.Sleep(delay)
 			}

localparticipant.go

@@ -747,7 +747,7 @@ func (p *LocalParticipant) updateSubscriptionPermissionLocked() {
 	}
 
 	if err := p.engine.SendSubscriptionPermission(p.subscriptionPermission); err != nil {
-		logger.Errorw(
+		p.log.Errorw(
 			"could not send subscription permission", err,
 			"participant", p.identity,
 			"participantID", p.sid,

remoteparticipant.go

@@ -112,6 +112,7 @@ func (p *RemoteParticipant) addSubscribedMediaTrack(
 				}
 				time.Sleep(50 * time.Millisecond)
 			}
+			p.engine.log.Warnw("timed out waiting for track publication metadata", nil, "trackSID", trackSID, "participant", p.Identity())
 			p.Callback.OnTrackSubscriptionFailed(trackSID, p)
 			p.roomCallback.OnTrackSubscriptionFailed(trackSID, p)
 		}()

room.go

@@ -870,6 +870,7 @@ func (r *Room) OnDisconnected(reason DisconnectionReason) {
 }
 
 func (r *Room) OnRestarting() {
+	r.log.Infow("room connection restarting")
 	r.setConnectionState(ConnectionStateReconnecting)
 	r.callback.OnReconnecting()
 
@@ -897,11 +898,13 @@ func (r *Room) OnRestarted(
 }
 
 func (r *Room) OnResuming() {
+	r.log.Infow("room connection resuming")
 	r.setConnectionState(ConnectionStateReconnecting)
 	r.callback.OnReconnecting()
 }
 
 func (r *Room) OnResumed() {
+	r.log.Infow("room connection resumed")
 	r.setConnectionState(ConnectionStateConnected)
 	r.callback.OnReconnected()
 	r.sendSyncState()