First cut

src/hooks/useJobSocket.js

@@ -0,0 +1,35 @@
+import { useEffect, useRef, useCallback } from 'react';
+
+/**
+ * Connect to the server WebSocket.
+ * @param {(msg: object) => void} onMessage  Called with parsed JSON messages.
+ */
+export function useJobSocket(onMessage) {
+  const wsRef = useRef(null);
+  const onMessageRef = useRef(onMessage);
+  onMessageRef.current = onMessage;
+
+  const connect = useCallback(() => {
+    const proto = location.protocol === 'https:' ? 'wss' : 'ws';
+    const ws = new WebSocket(`${proto}://${location.host}/ws`);
+    wsRef.current = ws;
+
+    ws.onmessage = (e) => {
+      try {
+        onMessageRef.current(JSON.parse(e.data));
+      } catch (_) {}
+    };
+
+    ws.onclose = () => {
+      // Auto-reconnect after 2 s
+      setTimeout(connect, 2000);
+    };
+
+    return ws;
+  }, []);
+
+  useEffect(() => {
+    const ws = connect();
+    return () => ws.close();
+  }, [connect]);
+}