fix(diagnostics): say which read failed, and let Live restart

- "Load older" is not offered off a loading filter's placeholder rows,
  whose cursor belongs to the previous filter.
- A failed older page, stale rows and missing counts each get their own
  message (HU/EN).
- Live shows as off once a failed read stopped the polling; pressing it
  again reads now.

frontend/src/components/AdminLogs.tsx

@@ -105,11 +105,26 @@ export default function AdminLogs() {
     placeholderData: keepPreviousData,
     refetchInterval: (q) => (live && q.state.status !== "error" ? LIVE_MS * 4 : false),
   });
-  // What "Load older" continues from — read off the data, since `hasNextPage` is off while live.
-  const olderCursor = logs.data?.pages[logs.data.pages.length - 1]?.next_cursor ?? null;
-  // A read failed while rows (or counts) were already on screen: they are kept, and said to be old.
-  const stale = (logs.isError && !!logs.data) || facets.isError;
-  const retryStale = () => {
+  // A failed read stops the polling (the intervals above); the button shows that, and pressing it
+  // again reads now.
+  const polling = live && !logs.isError;
+  // What "Load older" continues from — read off the data, since `hasNextPage` is off while live; not
+  // off placeholder rows, which are the previous filter's.
+  const olderCursor = logs.isPlaceholderData
+    ? null
+    : (logs.data?.pages[logs.data.pages.length - 1]?.next_cursor ?? null);
+  // A read that failed while lines were on screen: they are kept, and the message says what the
+  // failure means for them. (With no lines, the list's own error state says it.)
+  const failure = !logs.data
+    ? null
+    : logs.isFetchNextPageError
+      ? "olderFailed"
+      : logs.isError || (facets.isError && facets.data)
+        ? "stale"
+        : facets.isError
+          ? "countsFailed"
+          : null;
+  const retryFailed = () => {
     if (logs.isFetchNextPageError) void logs.fetchNextPage();
     else if (logs.isError) void logs.refetch();
     if (facets.isError) void facets.refetch();
@@ -129,13 +144,17 @@ export default function AdminLogs() {
     id === "none" ? t("adminLogs.noAccount") : (accounts[id] ?? `#${id}`);
 
   const toggleLive = () => {
-    if (!live) {
-      // Watching the top: drop the older pages now; `liveRef` keeps each tick to the first page.
-      qc.setQueryData<typeof logs.data>(key, (d) =>
-        d ? { pages: d.pages.slice(0, 1), pageParams: d.pageParams.slice(0, 1) } : d,
-      );
+    if (polling) {
+      setLive(false);
+      return;
     }
-    setLive(!live);
+    // Watching the top: drop the older pages now; `liveRef` keeps each tick to the first page.
+    qc.setQueryData<typeof logs.data>(key, (d) =>
+      d ? { pages: d.pages.slice(0, 1), pageParams: d.pageParams.slice(0, 1) } : d,
+    );
+    setLive(true);
+    if (logs.isError) void logs.refetch();
+    if (facets.isError) void facets.refetch();
   };
 
   const loadOlder = () => {
@@ -256,10 +275,10 @@ export default function AdminLogs() {
             />
             <span className="ml-auto flex gap-1.5">
               <Button
-                variant={live ? "outline-accent" : "outline"}
+                variant={polling ? "outline-accent" : "outline"}
                 size="xs"
                 icon={<Radio className="h-3.5 w-3.5" />}
-                aria-pressed={live}
+                aria-pressed={polling}
                 onClick={toggleLive}
               >
                 {t("adminLogs.live")}
@@ -296,14 +315,14 @@ export default function AdminLogs() {
             </div>
           )}
 
-          {stale && (
+          {failure && (
             <StateMessage
               tone="error"
               compact
-              onRetry={retryStale}
+              onRetry={retryFailed}
               className="border-b border-border"
             >
-              {t("adminLogs.stale")}
+              {t(`adminLogs.${failure}`)}
             </StateMessage>
           )}