Retained.kt

// In an activity:
private val presenter by retain { entry ->
  // entry exposes the viewModelScope, savedStateHandle, and a way to listen to onClear()
  MyPresenter() 
}

// Or in a composable, implicitly:
val presenter = retain { MyPresenter() } // this will look at LocalViewModelStoreOwner.current
// Or explicitly:
val activity = ...
val presenter = retain (owner = activity) { MyPresenter() } 

// In a Compose NavHost:
composable(route = "myRoute") { navBackStackEntry ->
  val presenter = retain(navBackStackEntry) { MyPresenter() }
}