fix(ui): отделить ошибки статистики от пустых данных

app/(main)/statistics/page.tsx

@@ -9,6 +9,7 @@ import {
   ServerIcon,
   UsersIcon,
 } from "lucide-react"
+import { Button } from "@/components/ui/button"
 import { PageHeader } from "@/components/page-header"
 import { KpiStatGrid } from "@/components/reui-kit/kpi-stat-grid"
 import { DataPageCard } from "@/components/data-page-card"
@@ -243,10 +244,16 @@ function StatisticsPageInner() {
   const pivotRow = useMemo(() => readPivotDim(searchParams, "pivotRow", "country"), [searchParams])
   const pivotCol = useMemo(() => readPivotDim(searchParams, "pivotCol", "service"), [searchParams])
 
-  const [data, setData] = useState<StatisticsDto>(EMPTY)
-  const [pivot, setPivot] = useState<StatisticsPivotDto>(EMPTY_PIVOT)
-  const [loading, setLoading] = useState(false)
-  const [error, setError] = useState<string | null>(null)
+  const [retry, setRetry] = useState(0)
+  const requestKey = JSON.stringify({ backendUrl, isLive, range, slices, view, pivotRow, pivotCol, planes, retry })
+  const [result, setResult] = useState<{
+    key: string; data: StatisticsDto; pivot: StatisticsPivotDto; error: string | null
+  } | null>(null)
+  const current = result?.key === requestKey ? result : null
+  const loading = isLive && current === null
+  const error = current?.error ?? null
+  const dataReady = isLive && current !== null && !error
+  const pivot = dataReady ? current.pivot : EMPTY_PIVOT
 
   const replaceParams = useCallback(
     (patch: Record<string, string | undefined>) => {
@@ -287,37 +294,32 @@ function StatisticsPageInner() {
     if (!prefsHydrated || !isLive) return
     let cancelled = false
     void (async () => {
-      setLoading(true)
-      setError(null)
       try {
         const query = toQuery(range, slices, planes)
         const dto = await getStatistics(backendUrl, query)
-        if (!cancelled) setData(dto)
+        if (cancelled) return
+        let matrix = EMPTY_PIVOT
         if (view === "pivot" && pivotRow !== pivotCol) {
-          const matrix = await getStatisticsPivot(backendUrl, {
+          matrix = await getStatisticsPivot(backendUrl, {
             ...query,
             row: pivotRow,
             col: pivotCol,
             metric: "bytes",
           })
-          if (!cancelled) setPivot(matrix)
         }
+        if (!cancelled) setResult({ key: requestKey, data: dto, pivot: matrix, error: null })
       } catch (e: unknown) {
         if (!cancelled) {
-          setData(EMPTY)
-          setPivot(EMPTY_PIVOT)
-          setError(e instanceof Error ? e.message : "Не удалось загрузить статистику")
+          setResult({ key: requestKey, data: EMPTY, pivot: EMPTY_PIVOT, error: e instanceof Error ? e.message : "Не удалось загрузить статистику" })
         }
-      } finally {
-        if (!cancelled) setLoading(false)
       }
     })()
     return () => {
       cancelled = true
     }
-  }, [backendUrl, isLive, prefsHydrated, range, slices, view, pivotRow, pivotCol, planes])
+  }, [backendUrl, isLive, prefsHydrated, range, slices, view, pivotRow, pivotCol, planes, requestKey])
 
-  const viewData = isLive ? data : EMPTY
+  const viewData = dataReady ? current.data : EMPTY
   const sliced = hasAnySlice(slices)
   const emptyCube = !isLive || (!loading && viewData.kpis.bytes === 0 && viewData.interfaces.length === 0)
 
@@ -369,13 +371,13 @@ function StatisticsPageInner() {
         ) : null}
 
         {error ? (
-          <Alert variant="destructive">
+          <Alert variant="destructive" role="alert">
             <AlertTitle>Ошибка загрузки</AlertTitle>
-            <AlertDescription>{error}</AlertDescription>
+            <AlertDescription>{error}<Button type="button" variant="outline" size="sm" onClick={() => setRetry(n => n + 1)}>Повторить загрузку</Button></AlertDescription>
           </Alert>
         ) : null}
 
-        {!slices.serverId && isLive && !emptyCube ? (
+        {!slices.serverId && dataReady && !emptyCube ? (
           <Alert>
             <AlertTitle>Уникальный объём</AlertTitle>
             <AlertDescription>
@@ -384,7 +386,7 @@ function StatisticsPageInner() {
           </Alert>
         ) : null}
 
-        <KpiStatGrid
+        {(dataReady || loading) && <KpiStatGrid
           aria-label="Сводка трафика"
           isLoading={loading}
           skeletonCount={5}
@@ -432,9 +434,9 @@ function StatisticsPageInner() {
               iconClassName: "text-muted-foreground",
             },
           ]}
-        />
+        />}
 
-        <StatisticsVolumeChart series={viewData.series} grain={viewData.grain} />
+        {dataReady && <StatisticsVolumeChart series={viewData.series} grain={viewData.grain} />}
 
         <DataPageCard>
           <DataPageToolbar
@@ -482,7 +484,7 @@ function StatisticsPageInner() {
               </div>
             }
             filterControl={<StatisticsFilters key={JSON.stringify(slices)} slices={slices} onApply={setSlices} />}
-            countLabel={countLabel}
+            countLabel={dataReady ? countLabel : undefined}
           />
           <SliceChips
             chips={chips}
@@ -492,7 +494,9 @@ function StatisticsPageInner() {
               setSlices(next)
             }}
           />
-          {emptyCube ? (
+          {isLive && !dataReady ? (
+            <div role="status" className="p-6 text-sm text-muted-foreground">{loading ? "Загрузка статистики…" : "Статистика недоступна. Повторите загрузку."}</div>
+          ) : emptyCube ? (
             <EmptyState
               title="Нет данных куба"
               description="За выбранный период нет IPFIX-фактов. Куб заполняется с момента деплоя, без бэкфилла за год."