Reactive Values

Use Popsicle.value for a small standalone mutable value:

final selectedTab = Popsicle.value(0);

Render:

selectedTab.ui(
  (index) => Text('$index'),
);

Mutate from a Scope:

scope.set(selectedTab, 2);
scope.update(selectedTab, (index) => index + 1);

Use a Store instead when the state grows behavior, multiple related fields, async orchestration, or effects.