Fix(Go): notify browsers with device_offline so the webpage not frozen

server/go/web/ws.go

@@ -229,8 +229,30 @@ func (h *wsHub) OnDeviceOnline(_ hub.DeviceInfo) {
 	h.broadcastAuthenticated(`{"cmd":"devices_changed"}`)
 }
 
-func (h *wsHub) OnDeviceOffline(_ string) {
+func (h *wsHub) OnDeviceOffline(id string) {
+	// Tell everyone authenticated to refresh their device list (covers
+	// users sitting on the devices-page).
 	h.broadcastAuthenticated(`{"cmd":"devices_changed"}`)
+
+	// Also tell any browser actively viewing this device's screen — the
+	// devices_changed handler only refreshes the list page; viewers on the
+	// screen page would otherwise see a frozen frame with "Connected" status
+	// indefinitely. The browser handles this by showing "Device offline" and
+	// bouncing back to the device list after 2 s.
+	if id == "" {
+		return
+	}
+	msg := mustJSON(map[string]any{
+		"cmd": "device_offline",
+		"id":  id,
+	})
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	for c := range h.clients {
+		if c.watching == id && c.token != "" {
+			c.queue(msg)
+		}
+	}
 }
 
 // OnCursorChange relays the remote cursor index to every viewer of this