fix: websocket race-condition and firmware upload

internal/websocket/websocket.go

@@ -26,6 +26,7 @@ type WebSocketServer struct {
 	sporeClients  map[string]*client.SporeClient
 	clients       map[*websocket.Conn]bool
 	mutex         sync.RWMutex
+	writeMutex    sync.Mutex // Mutex to serialize writes to WebSocket connections
 	logger        *log.Logger
 }
 
@@ -214,8 +215,11 @@ func (wss *WebSocketServer) broadcastClusterUpdate() {
 		"prep_time": broadcastTime.Sub(startTime),
 	}).Debug("Broadcasting cluster update to WebSocket clients")
 
-	// Send to all clients
+	// Send to all clients with write synchronization
 	var failedClients int
+	wss.writeMutex.Lock()
+	defer wss.writeMutex.Unlock()
+
 	for _, client := range clients {
 		client.SetWriteDeadline(time.Now().Add(5 * time.Second))
 		if err := client.WriteMessage(websocket.TextMessage, data); err != nil {
@@ -224,7 +228,7 @@ func (wss *WebSocketServer) broadcastClusterUpdate() {
 		}
 	}
 
-	totalTime := time.Now().Sub(startTime)
+	totalTime := time.Since(startTime)
 	wss.logger.WithFields(log.Fields{
 		"clients":        len(clients),
 		"failed_clients": failedClients,
@@ -263,6 +267,10 @@ func (wss *WebSocketServer) broadcastNodeDiscovery(nodeIP, action string) {
 		return
 	}
 
+	// Send to all clients with write synchronization
+	wss.writeMutex.Lock()
+	defer wss.writeMutex.Unlock()
+
 	for _, client := range clients {
 		client.SetWriteDeadline(time.Now().Add(5 * time.Second))
 		if err := client.WriteMessage(websocket.TextMessage, data); err != nil {
@@ -302,7 +310,7 @@ func (wss *WebSocketServer) updateLocalNodesWithAPI(apiMembers []client.ClusterM
 	wss.logger.WithField("members", len(apiMembers)).Debug("Updating local nodes with API data")
 
 	for _, member := range apiMembers {
-		if member.Labels != nil && len(member.Labels) > 0 {
+		if len(member.Labels) > 0 {
 			wss.logger.WithFields(log.Fields{
 				"ip":     member.IP,
 				"labels": member.Labels,