Fix ready channel race condition and implement Neko heartbeat protocol

Bug 1: In Start(), only replace the ready channel if the previous one
was already closed (reconnection case). Previously, Start() always
created a new channel, orphaning the one from NewRelay() and causing
the first client to always time out with a 503.
Bug 2: Extract heartbeat_interval from system/init payload and start
a periodic client/heartbeat sender. Remove dead system/heartbeat
handler (Neko never sends this event; it sends system/pong in
response to client-initiated heartbeats).

Author: cursoragent

server/lib/webrtcscreen/relay.go

@@ -94,7 +94,13 @@ func (r *Relay) ensureRunning() {
 // Start in a loop for automatic reconnection.
 func (r*Relay) Start(ctx context.Context) error {
 r.mu.Lock()
-r.ready=make(chanstruct{})
+select {
+case<-r.ready:
+// Previous connection closed the channel; create a fresh one.
+r.ready=make(chanstruct{})
+default:
+// Channel is still open (first call), keep it.
+	}
 r.mu.Unlock()
 
 token, err:=r.nekoLogin(ctx)
@@ -124,10 +130,35 @@ func (r *Relay) Start(ctx context.Context) error {
 r.mu.Unlock()
 	}()
 
-iferr:=r.waitForEvent(ctx, ws, "system/init"); err!=nil {
+initPayload, err:=r.waitForEvent(ctx, ws, "system/init")
+iferr!=nil {
 returnfmt.Errorf("waiting for system/init: %w", err)
 	}
 
+varinitDatastruct {
+HeartbeatIntervalfloat64`json:"heartbeat_interval"`
+	}
+ifinitPayload!=nil {
+_=json.Unmarshal(initPayload, &initData)
+	}
+
+ifinitData.HeartbeatInterval>0 {
+gofunc() {
+ticker:=time.NewTicker(time.Duration(initData.HeartbeatInterval*float64(time.Second)))
+deferticker.Stop()
+for {
+select {
+case<-ctx.Done():
+return
+case<-ticker.C:
+iferr:=sendWSMsg(ctx, ws, "client/heartbeat", nil); err!=nil {
+return
+ }
+ }
+ }
+ }()
+	}
+
 pc, err:=webrtc.NewPeerConnection(webrtc.Configuration{})
 iferr!=nil {
 returnfmt.Errorf("creating neko peer connection: %w", err)
@@ -502,15 +533,15 @@ func sendWSMsg(ctx context.Context, ws *cws.Conn, event string, payload json.Raw
 returnws.Write(ctx, cws.MessageText, data)
 }
 
-func (r*Relay) waitForEvent(ctx context.Context, ws*cws.Conn, eventstring) error {
+func (r*Relay) waitForEvent(ctx context.Context, ws*cws.Conn, eventstring) (json.RawMessage, error) {
 for {
 _, data, err:=ws.Read(ctx)
 iferr!=nil {
-returnerr
+returnnil, err
  }
 varmsgnekoMsg
 ifjson.Unmarshal(data, &msg) ==nil&&msg.Event==event {
-returnnil
+returnmsg.Payload, nil
  }
 	}
 }
@@ -545,8 +576,6 @@ func (r *Relay) nekoWSLoop(ctx context.Context, ws *cws.Conn, pc *webrtc.PeerCon
 continue
  }
 switchmsg.Event {
-case"system/heartbeat":
-_=sendWSMsg(ctx, ws, "client/heartbeat", nil)
 case"signal/candidate":
 varcandidate webrtc.ICECandidateInit
 ifjson.Unmarshal(msg.Payload, &candidate) ==nil {