diff --git a/control/internal/service/registry.go b/control/internal/service/registry.go
index 4e53a73..d582a1b 100644
--- a/control/internal/service/registry.go
+++ b/control/internal/service/registry.go
@@ -1,6 +1,7 @@
 package service
 
 import (
+    "log"
     "encoding/json"
     "sort"
     "strings"
@@ -92,6 +93,7 @@ func (s *RegistryService) startGraphPolling() {
                 onlineDevices = append(onlineDevices, dev)
             }
         }
+        log.Printf("[gp] tick total=%d online=%d", len(s.devices), len(onlineDevices))
         s.mu.RUnlock()
 
         for _, dev := range onlineDevices {
@@ -104,6 +106,7 @@ func (s *RegistryService) startGraphPolling() {
                 continue
             }
             total, online, down := parseVideoSourceStats(graphs)
+            log.Printf("[gp] device=%s vs_total=%d vs_online=%d vs_down=%d", dev.DeviceID, total, online, down)
             s.mu.Lock()
             // discovery 可能已替换设备指针，更新 registry 中当前对象
             if cur, ok := s.devices[dev.DeviceID]; ok {
@@ -111,6 +114,9 @@ func (s *RegistryService) startGraphPolling() {
                 cur.VideoSourceTotal = total
                 cur.VideoSourceOnline = online
                 cur.VideoSourceDown = down
+                log.Printf("[gp] updated %s vs_down=%d", dev.DeviceID, cur.VideoSourceDown)
+            } else {
+                log.Printf("[gp] MISSING device %s in registry", dev.DeviceID)
             }
             s.mu.Unlock()
         }