How to intercept Back press in Navigation3 to switch Bottom Navigation tabs?

Body:

I am implementing the new androidx.navigation3 library in my Jetpack Compose project. I am using a custom Navigator class (injected via Koin) to manage the global backStack.

The Architecture:

Global Navigation: Managed by NavDisplay and a SnapshotStateList.

Bottom Navigation: Implemented as a single Destination (Dashboard) in the global stack. Inside Dashboard, I switch screens using local var currentTab state.

The Problem: When I navigate to the Dashboard and switch to a secondary tab (e.g., "Profile"), pressing the system Back button triggers the global NavDisplay's onBack, which pops the Dashboard screen entirely and closes the app.

Desired Behavior:

If on "Profile" tab -> Back press switches to "Home" tab.

If on "Home" tab -> Back press pops the screen (closes app).

Code Snippets:

1. Navigator.kt (Global State)

Kotlin

class Navigator(startDestination: Any) { val backStack: SnapshotStateList<Any> = mutableStateListOf(startDestination) fun goBack() { backStack.removeLastOrNull() } }

2. RootNavHost.kt (Entry Point)

Kotlin

@Composable fun RootNavHost() { val navigator = koinInject<Navigator>() NavDisplay( backStack = navigator.backStack, onBack = { navigator.goBack() }, // <--- This fires immediately entryProvider = remember(navigator) { entryProvider<Any> { entry<Dashboard> { MainScaffold() } // ... other entries } } ) }

3. MainScaffold.kt (Bottom Nav)

Kotlin

@Composable fun MainScaffold() { // Local state managing the tabs var currentTab by rememberSaveable { mutableStateOf(AppTab.Home) } Scaffold( bottomBar = { // NavigationBar implementation modifying currentTab } ) { padding -> // Switching content based on currentTab when (currentTab) { AppTab.Home -> HomeScreen(...) AppTab.Profile -> ProfileScreen(...) } } }

Question: In the context of Navigation3, what is the recommended pattern to handle this? Should I be using a BackHandler inside MainScaffold to intercept the back event before it reaches NavDisplay, or is there a way to integrate the Dashboard internal state into the Navigator backstack?