Trigger one-time Flutter effects

Rendering and effects have different responsibilities. Keep visible state in Builder or Selector and use UseCaseListener for navigation, dialogs, snackbars, or analytics.

UseCaseListener<LoginUseCase, LoginState>(
  listenWhen: (previous, current) =>
      previous.state.session != current.state.session,
  listener: (context, snapshot) {
    if (snapshot.state.session != null) {
      Navigator.of(context).pop();
    }
  },
  child: const LoginForm(),
)

Listener skips the Snapshot replayed when it subscribes, so mounting a screen does not repeat an old effect. Use UseCaseConsumer when one subscription must both build and listen; its filters remain independent.

Stream onError handles errors delivered by the Snapshot stream. It does not replace command-level error handling in core.