Fix: sse updates

broker/sse.go

@@ -52,11 +52,20 @@ func (broker *Broker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "text/event-stream")
 	w.Header().Set("Cache-Control", "no-cache")
 	w.Header().Set("Connection", "keep-alive")
-	w.Header().Set("Access-Control-Allow-Origin", "*")
+	// w.Header().Set("Access-Control-Allow-Origin", "*")
+	origin := r.Header.Get("Origin")
+	if origin == "" {
+		origin = "*" // Fallback for non-browser clients
+	}
+	w.Header().Set("Access-Control-Allow-Origin", origin)
+	w.Header().Set("Access-Control-Allow-Credentials", "true")
 	messageChan := make(NotifierChan)
 	broker.newClients <- messageChan
 	defer func() { broker.closingClients <- messageChan }()
 	ctx := r.Context()
+	// browser can close sse on its own
+	heartbeat := time.NewTicker(15 * time.Second)
+	defer heartbeat.Stop()
 	for {
 		select {
 		case <-ctx.Done():
@@ -70,6 +79,12 @@ func (broker *Broker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				return
 			}
 			w.(http.Flusher).Flush()
+		case <-heartbeat.C:
+			// Send SSE heartbeat comment
+			if _, err := w.Write([]byte(": heartbeat\n\n")); err != nil {
+				return // Client disconnected
+			}
+			w.(http.Flusher).Flush()
 		}
 	}
 }
@@ -95,7 +110,8 @@ func (broker *Broker) Listen() {
 				select {
 				case clientMessageChan <- event:
 				case <-time.After(patience):
-					slog.Info("Client was skipped", "clients listening", len(broker.clients))
+					delete(broker.clients, clientMessageChan)
+					slog.Info("Client was removed", "clients listening", len(broker.clients))
 				}
 			}
 		}