improve provider lifetime

app/lib/extensions/ref_cache.dart

@@ -0,0 +1,17 @@
+import 'dart:async';
+
+import 'package:riverpod/riverpod.dart';
+
+extension CacheForExtension on Ref {
+  /// Keeps the provider alive for [duration].
+  void cacheFor(Duration duration) {
+    // Immediately prevent the state from getting destroyed.
+    final link = keepAlive();
+    // After duration has elapsed, we re-enable automatic disposal.
+    final timer = Timer(duration, link.close);
+
+    // Optional: when the provider is recomputed (such as with ref.watch),
+    // we cancel the pending timer.
+    onDispose(timer.cancel);
+  }
+}