diff --git a/internal/service/config_assets.go b/internal/service/config_assets.go
index e2d21f1..be112f7 100644
--- a/internal/service/config_assets.go
+++ b/internal/service/config_assets.go
@@ -1830,3 +1830,22 @@ func intValue(v any) int {
         return 0
     }
 }
+
+// ResolveChannelToSource maps an alarm channel (e.g. "src_52ef4499_alarm_violation")
+// to its video source name (e.g. "5跨主通道").
+func (s *ConfigPreviewService) ResolveChannelToSource(channel string) string {
+	if s == nil {
+		return channel
+	}
+	unitName := channel
+	if idx := strings.LastIndex(channel, "_alarm_"); idx > 0 {
+		unitName = channel[:idx]
+	}
+	units, _ := s.ListRecognitionUnits()
+	for _, u := range units {
+		if u.Name == unitName && u.VideoSourceRef != "" {
+			return u.VideoSourceRef
+		}
+	}
+	return channel
+}
diff --git a/internal/web/ui.go b/internal/web/ui.go
index f564f20..8f12269 100644
--- a/internal/web/ui.go
+++ b/internal/web/ui.go
@@ -595,7 +595,12 @@ func NewUI(discovery *service.DiscoveryService, registry *service.RegistryServic
                 return ""
             }
         },
-        "alarmChannelSource": alarmChannelSource,
+        "alarmChannelSource": func(channel string) string {
+            if len(preview) > 0 && preview[0] != nil {
+                return preview[0].ResolveChannelToSource(channel)
+            }
+            return channel
+        },
         "statusLabel": func(v string) string {
             switch strings.TrimSpace(v) {
             case "unacknowledged":
@@ -2580,24 +2585,12 @@ func (u *UI) pageAlarms(w http.ResponseWriter, r *http.Request) {
     // Build device name/IP maps and channel→source map for template
     data.AlarmDeviceNames = map[string]string{}
     data.AlarmDeviceIPs = map[string]string{}
-    data.AlarmChannelSources = map[string]string{}
     for _, dev := range data.Devices {
         if dev != nil {
             data.AlarmDeviceNames[dev.DeviceID] = dev.DisplayName()
             data.AlarmDeviceIPs[dev.DeviceID] = dev.IP
         }
     }
-    if u.preview != nil {
-        if assignments, err := u.preview.ListDeviceAssignments(); err == nil {
-            for _, a := range assignments {
-                for _, ref := range a.RecognitionUnits {
-                    if unit, err := u.preview.GetRecognitionUnit(ref); err == nil && unit != nil && unit.VideoSourceRef != "" {
-                        data.AlarmChannelSources[unit.Name] = unit.VideoSourceRef
-                    }
-                }
-            }
-        }
-    }
     // Calculate total pages and build page list: 1, ..., cur-2, cur-1, cur, cur+1, cur+2, ..., N
     if data.TotalAlarmCount > 0 {
         data.TotalAlarmPages = (data.TotalAlarmCount + perPage - 1) / perPage
@@ -2742,19 +2735,6 @@ func (u *UI) apiAlarmExport(w http.ResponseWriter, r *http.Request) {
             deviceMap[d.DeviceID] = d
         }
     }
-    // Channel→source lookup (channel = recognition unit name)
-    channelSources := map[string]string{}
-    if u.preview != nil {
-        if assignments, _ := u.preview.ListDeviceAssignments(); len(assignments) > 0 {
-            for _, a := range assignments {
-                for _, ref := range a.RecognitionUnits {
-                    if unit, err := u.preview.GetRecognitionUnit(ref); err == nil && unit != nil && unit.VideoSourceRef != "" {
-                        channelSources[unit.Name] = unit.VideoSourceRef
-                    }
-                }
-            }
-        }
-    }
 
     w.Header().Set("Content-Type", "text/csv; charset=utf-8")
     w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="alarms_%s_%s.csv"`, from, to))
@@ -2768,7 +2748,7 @@ func (u *UI) apiAlarmExport(w http.ResponseWriter, r *http.Request) {
             devName = dev.DisplayName()
             devIP = dev.IP
         }
-        sourceName := alarmChannelSource(a.Channel, channelSources)
+        sourceName := u.preview.ResolveChannelToSource(a.Channel)
         fmt.Fprintf(w, "%s,%s,%s,%s,%s,%s,%s\n",
             escapeCSV(formatAlarmTime(a.Timestamp)), escapeCSV(devName), escapeCSV(devIP), escapeCSV(sourceName),
             escapeCSV(alarmRuleLabel(a.RuleName)), escapeCSV(a.ObjectLabel),
@@ -2815,30 +2795,14 @@ func alarmStatusLabel(v string) string {
     }
 }
 
-// alarmChannelSource resolves an alarm channel (e.g. "cam1_alarm_violation") to its video source name.
-// The channel format is {instanceName}_alarm_{type}, where instanceName matches the recognition unit.
-func alarmChannelSource(channel string, sources map[string]string) string {
-    // Try exact match first
-    if src, ok := sources[channel]; ok {
-        return src
-    }
-    // Strip suffix: cam1_alarm_violation → cam1
-    if idx := strings.LastIndex(channel, "_alarm_"); idx > 0 {
-        if src, ok := sources[channel[:idx]]; ok {
-            return src
-        }
-    }
-    return channel
-}
-
 func formatAlarmTime(t string) string {
     // 2026-07-22T13:03:20+08:00 → 2026-07-22 13:03:20
     s := strings.TrimSpace(t)
     s = strings.Replace(s, "T", " ", 1)
-    if idx := strings.Index(s, "+"); idx > 0 {
-        s = s[:idx]
+    if idx := strings.LastIndex(s, "+"); idx > 10 {
+        s = strings.TrimSpace(s[:idx])
     }
-    return strings.TrimSpace(s)
+    return s
 }
 
 func (u *UI) pageResources(w http.ResponseWriter, r *http.Request) {
diff --git a/internal/web/ui/templates/alarms.html b/internal/web/ui/templates/alarms.html
index c3838e0..68ccf1d 100644
--- a/internal/web/ui/templates/alarms.html
+++ b/internal/web/ui/templates/alarms.html
@@ -62,7 +62,7 @@
             <a href="/devices/{{.DeviceID}}">{{index $.AlarmDeviceNames .DeviceID}}</a>
             <div class="muted small mono">{{index $.AlarmDeviceIPs .DeviceID}}</div>
           </td>
-          <td>{{alarmChannelSource .Channel $.AlarmChannelSources}}</td>
+          <td>{{alarmChannelSource .Channel}}</td>
           <td>
             <span class="pill warn">{{ruleLabel .RuleName}}</span>
           </td>
diff --git a/safesightd-linux-arm64 b/safesightd-linux-arm64
index 256c284..b7496dd 100644
Binary files a/safesightd-linux-arm64 and b/safesightd-linux-arm64 differ