fix(ui): проверять источник IPv4 для диагностики

app/(main)/probes/page.tsx

@@ -2,6 +2,7 @@
 
 import { Suspense, useEffect, useRef, useState, useMemo, useCallback } from "react"
 import { useSearchParams } from "next/navigation"
+import { readProbeSource } from "@/lib/probe-source"
 import { readProbeUrl, patchProbeUrl } from "@/lib/probe-url"
 import { PageHeader } from "@/components/page-header"
 import { FormToggle } from "@/components/form-kit"
@@ -616,7 +617,8 @@ function ProbesContent() {
   const [bwDuration, setBwDuration]  = useState(10)
   const [runBusy, setRunBusy]        = useState(false)
   /** В live: IPv4 для src-address (DNS A-запись к host API); undefined = грузим, null = не удалось */
-  const [rosSrcV4, setRosSrcV4] = useState<string | null | undefined>(undefined)
+  const [source, setSource] = useState<{ key: string; ipv4?: string | null; error?: string; loading: boolean } | null>(null)
+  const [sourceRevision, setSourceRevision] = useState(0)
 
   useEffect(() => {
     if (!isLive || !canRead) return
@@ -664,27 +666,6 @@ function ProbesContent() {
     }))
   ), [allServers])
 
-  useEffect(() => {
-    if (!isLive || !canRead || liveLoad !== "idle" || !allServers.some(s => s.id === srcId && s.enabled)) {
-      queueMicrotask(() => setRosSrcV4(undefined))
-      return
-    }
-    const n = Number.parseInt(srcId, 10)
-    if (!Number.isFinite(n)) {
-      setRosSrcV4(undefined)
-      return
-    }
-    let cancelled = false
-    setRosSrcV4(undefined)
-    void apiFetch<{ ipv4: string | null }>(`/api/servers/${n}/ros-src-address`)
-      .then((r) => {
-        if (!cancelled) setRosSrcV4(r.ipv4)
-      })
-      .catch(() => {
-        if (!cancelled) setRosSrcV4(null)
-      })
-    return () => { cancelled = true }
-  }, [isLive, canRead, liveLoad, allServers, srcId, apiFetch])
 
   useEffect(() => {
     if (!isLive || !canReadGre || liveLoad !== "idle" || !allServers.some(s => s.id === srcId && s.enabled)) return
@@ -735,6 +716,22 @@ function ProbesContent() {
 
   const bwTunnels = tunnelsForSrc
   const srcServer = useMemo(() => allServers.find(s => s.id === srcId), [allServers, srcId])
+  const sourceKey = JSON.stringify([srcId, srcServer?.host])
+  const sourceRequired = tool === "ping" || tool === "traceroute" || tool === "mtu"
+  const sourceCurrent = source?.key === sourceKey ? source : null
+  const rosSrcV4 = sourceCurrent?.ipv4
+  useEffect(() => {
+    if (!isLive || !canRead || liveLoad !== "idle" || !srcServer?.enabled || !sourceRequired) return
+    const host = srcServer.host, id = srcServer.id
+    if (!/^[1-9][0-9]*$/.test(id) || !Number.isSafeInteger(Number(id))) return
+    let cancelled = false
+    const ctrl = new AbortController()
+    queueMicrotask(() => { if (!cancelled) setSource({ key: sourceKey, loading: true }) })
+    void apiFetch<unknown>("/api/servers/" + id + "/ros-src-address", { signal: ctrl.signal })
+      .then(raw => { const ipv4 = readProbeSource(raw, host); if (!cancelled) setSource({ key: sourceKey, loading: false, ipv4 }) })
+      .catch(error => { if (!cancelled) setSource({ key: sourceKey, loading: false, error: error instanceof Error ? error.message : "Источник preview неизвестен." }) })
+    return () => { cancelled = true; ctrl.abort() }
+  }, [isLive, canRead, liveLoad, srcServer, sourceRequired, sourceKey, apiFetch, sourceRevision])
   const greReady = !isLive || (greState?.id === srcId && greState.state === "ready")
   const bwTun     = useMemo(() => bwTunnels.find(t => t.id === bwTunId), [bwTunnels, bwTunId])
 
@@ -1000,6 +997,15 @@ function ProbesContent() {
             </div>
           )}
 
+          {isLive && srcServer?.enabled && sourceRequired && (
+            <div className="text-xs text-muted-foreground">
+              {sourceCurrent?.error ? <div role="alert" aria-label="Источник preview"><p>{sourceCurrent.error}</p><Button type="button" size="sm" variant="outline" onClick={() => setSourceRevision(n => n + 1)}>Повторить определение IPv4</Button></div>
+                : !sourceCurrent || sourceCurrent.loading ? <p role="status">Определяем IPv4 для preview…</p>
+                : <p role="status">{sourceCurrent.ipv4 === null ? "IPv4 для preview не определён." : "IPv4 для preview: " + sourceCurrent.ipv4}</p>}
+              <p>Preview справочный. Backend повторно определяет источник при запуске; пустой результат не подтверждает исходный адрес команды.</p>
+            </div>
+          )}
+
           {/* ── tool selector + config ── */}
           <OpsPanel contentClassName="pt-4 pb-4 px-4 flex flex-col gap-4">