fix(ui): различать ошибку и пустые данные VXLAN

app/(main)/vxlan/page.tsx

@@ -1,6 +1,6 @@
 "use client"
 
-import { Suspense, useCallback, useEffect, useMemo, useState } from "react"
+import { Suspense, useCallback, useEffect, useMemo, useRef, useState } from "react"
 import Link from "next/link"
 import { useRouter, useSearchParams } from "next/navigation"
 import { Alert as ContextAlert, AlertTitle as ContextTitle, AlertDescription as ContextDescription } from "@/components/reui/alert"
@@ -139,10 +139,14 @@ function VxlanPageContent({ selectedServerId, selectedTunnelId, allTunnelsHref,
   const [liveTunnels, setLiveTunnels] = useState<VxlanTunnel[]>([])
   const [liveServers, setLiveServers] = useState<Server[]>([])
   const [loading, setLoading] = useState(true)
+  const [hasLoaded, setHasLoaded] = useState(false)
+  const loadEpoch = useRef(0)
+  useEffect(() => () => { loadEpoch.current += 1 }, [backendUrl, isLive])
   const [liveError, setLiveError] = useState<string | null>(null)
 
   const loadLive = useCallback(async () => {
     if (!isLive) return
+    const epoch = ++loadEpoch.current
     setLoading(true)
     setLiveError(null)
     try {
@@ -150,12 +154,16 @@ function VxlanPageContent({ selectedServerId, selectedTunnelId, allTunnelsHref,
         requestJson<VxlanApiResponse>(backendUrl, "/api/vxlan"),
         requestJson<BackendServer[]>(backendUrl, "/api/servers"),
       ])
-      setLiveTunnels(tunnelsRes.tunnels ?? [])
+      if (epoch !== loadEpoch.current) return
+      if (!Array.isArray(tunnelsRes?.tunnels) || !Array.isArray(serversRes)) throw new Error("Некорректный ответ загрузки VXLAN")
+      setLiveTunnels(tunnelsRes.tunnels)
+      setHasLoaded(true)
       setLiveServers(serversRes.filter((s) => s.enabled).map(mapBackendServer))
     } catch (e) {
+      if (epoch !== loadEpoch.current) return
       setLiveError(e instanceof Error ? e.message : "Ошибка загрузки")
     } finally {
-      setLoading(false)
+      if (epoch === loadEpoch.current) setLoading(false)
     }
   }, [isLive, backendUrl])
 
@@ -273,6 +281,8 @@ function VxlanPageContent({ selectedServerId, selectedTunnelId, allTunnelsHref,
               <AlertDescription className="text-xs">Ошибка загрузки: {liveError}</AlertDescription>
             </Alert>
           )}
+          {isLive && loading && <p role="status" className="text-sm text-muted-foreground">{hasLoaded ? "Обновление VXLAN…" : "Загрузка VXLAN…"}</p>}
+          {isLive && liveError && hasLoaded && <p className="text-sm text-muted-foreground">Показаны последние полученные данные; они могут быть устаревшими.</p>}
           {selectedTunnelId === null && isLive && !loading && displayTunnels.length === 0 && !liveError && (
             <div className="rounded-md border border-border bg-muted/30 px-4 py-6 text-center text-sm text-muted-foreground">
               На опрошенных серверах нет VXLAN-интерфейсов
@@ -290,28 +300,28 @@ function VxlanPageContent({ selectedServerId, selectedTunnelId, allTunnelsHref,
               {
                 id: "tunnels",
                 label: "Туннелей",
-                value: scopedTunnels.length,
+                value: isLive && !hasLoaded ? "—" : scopedTunnels.length,
                 icon: <NetworkIcon className="size-4" />,
                 iconClassName: "text-muted-foreground",
               },
               {
                 id: "up",
                 label: "Активных",
-                value: upCount,
+                value: isLive && !hasLoaded ? "—" : upCount,
                 icon: <LayersIcon className="size-4" />,
                 iconClassName: "text-success",
               },
               {
                 id: "vni",
                 label: "Уникальных VNI",
-                value: vnis,
+                value: isLive && !hasLoaded ? "—" : vnis,
                 icon: <LayersIcon className="size-4" />,
                 iconClassName: "text-info",
               },
               {
                 id: "servers",
                 label: "Серверов",
-                value: new Set(scopedTunnels.map((t) => t.serverId)).size,
+                value: isLive && !hasLoaded ? "—" : new Set(scopedTunnels.map((t) => t.serverId)).size,
                 icon: <NetworkIcon className="size-4" />,
                 iconClassName: "text-primary",
               },