Package-level declarations

Thin wrapper over one Navigation3 NavBackStack — the object registered in NavigatorsHolder under a navigatorId, and what Navigate/NavigateUp/NavigateClearingStack actually operate on. One instance per backstack — the app's own root one (built in MosaicApplication) and one per currently-composed NestedNavigationGraph tile.

App-wide lookup table of NavigationControllers by navigatorId — lets Navigate/NavigateUp/ NavigateClearingStack trigger navigation on any registered backstack by name, from any event chain, without the backstack itself (which only really exists near the top of the Compose tree) being threaded down as a parameter. A single Koin single. MosaicApplication registers the app's own root backstack under the conventional id "root"; a custom container tile hosting its own nested navigation graph (the way NestedNavigationGraph does) registers its own backstack the same way, under whatever navigatorId the DSL author chose for it.

Where to pop a backstack up to before pushing a new destination — Navigate's popUpTo parameter.

Builds a PopUpTo — the DSL helper behind Navigate's popUpTo = poppingUpTo(...) parameter.