Initial scaffold: React+TS+Vite frontend, FastAPI backend, config system

frontend/src/hooks/useAlerts.ts

@@ -0,0 +1,35 @@
+import { useEffect, useRef } from 'react';
+import { AlertWebSocket } from '@/services/alerts';
+import { useAlertStore } from '@/stores/alertStore';
+import { useConfigStore } from '@/stores/configStore';
+
+export function useAlerts() {
+  const wsRef = useRef<AlertWebSocket | null>(null);
+  const config = useConfigStore((s) => s.config);
+  const { showAlert, isSuppressed, activeAlert } = useAlertStore();
+
+  useEffect(() => {
+    if (!config?.alerts.enabled) return;
+
+    const ws = new AlertWebSocket();
+    wsRef.current = ws;
+
+    const unsub = ws.subscribe((event) => {
+      // Don't show if there's already an active alert
+      if (useAlertStore.getState().activeAlert) return;
+
+      // Check suppression
+      if (isSuppressed(event.camera, config.alerts.suppression_seconds)) return;
+
+      showAlert(event);
+    });
+
+    ws.connect();
+
+    return () => {
+      unsub();
+      ws.disconnect();
+      wsRef.current = null;
+    };
+  }, [config?.alerts.enabled]);
+}