Split multi-hook frontend modules into single-hook files

frontend/src/hooks/useBlocklistStatus.ts

@@ -0,0 +1,45 @@
+/**
+ * React hook for polling blocklist schedule error state.
+ */
+
+import { useEffect, useState } from "react";
+import { fetchSchedule } from "../api/blocklist";
+
+const BLOCKLIST_POLL_INTERVAL_MS = 60_000;
+
+export interface UseBlocklistStatusReturn {
+  hasErrors: boolean;
+}
+
+/**
+ * Poll `GET /api/blocklists/schedule` every 60 seconds to detect whether
+ * the most recent blocklist import had errors.
+ */
+export function useBlocklistStatus(): UseBlocklistStatusReturn {
+  const [hasErrors, setHasErrors] = useState(false);
+
+  useEffect(() => {
+    let cancelled = false;
+
+    const poll = (): void => {
+      fetchSchedule()
+        .then((info) => {
+          if (!cancelled) {
+            setHasErrors(info.last_run_errors === true);
+          }
+        })
+        .catch(() => {
+          // Silently swallow network errors — do not change indicator state.
+        });
+    };
+
+    poll();
+    const id = window.setInterval(poll, BLOCKLIST_POLL_INTERVAL_MS);
+    return (): void => {
+      cancelled = true;
+      window.clearInterval(id);
+    };
+  }, []);
+
+  return { hasErrors };
+}