watch_it Expert - Reactive Widget State Management

What: Reactive widgets that auto-rebuild when ValueListenables/Listenables, Streams, or Futures change. Built on get_it. Provides di global alias for GetIt.I.

CRITICAL RULES

• ORDERING: All watch*(), registerHandler*(), createOnce(), callOnce() calls MUST execute in the same order on every build (like React Hooks)
• Widget type: Must extend WatchingWidget / WatchingStatefulWidget or use WatchItMixin / WatchItStatefulWidgetMixin
• Never in callbacks: Don't call watch functions inside builders, callbacks, or event handlers
• watchValue selector MUST return a ValueListenable<R>, not a bare value
• createOnce works in BOTH stateless and stateful widgets

Widget Types

ALWAYS prefer WatchingWidget / WatchingStatefulWidget for new code. Only use the mixin variants (WatchItMixin / WatchItStatefulWidgetMixin) when:

• The widget needs additional mixins (e.g. TickerProviderStateMixin)
• You're adding watch_it to existing code and don't want to change the base class