Android / KMP Navigation

Principles

• Type-safe navigation with @Serializable route objects (KotlinX Serialization).
• One nav graph per feature, defined in the feature's presentation module.
• Feature nav graphs are assembled in :app.
• Navigation within a feature uses a NavController passed into the feature nav graph.
• Feature-to-feature navigation uses callbacks, keeping features decoupled.

Route Objects

Define routes as @Serializable objects or data classes in the feature's presentation module:

// feature:notes:presentation
@Serializable object NoteListRoute
@Serializable data class NoteDetailRoute(val noteId: String)

Use data object for screens with no parameters, data class for screens with arguments.

Feature Nav Graph

Each feature exposes a NavGraphBuilder extension function:

// feature:notes:presentation
fun NavGraphBuilder.notesGraph(
    navController: NavController,
    onNavigateToEditor: (String) -> Unit  // callback for cross-feature navigation
) {
    navigation<NoteListRoute>(startDestination = NoteListRoute) {
        composable<NoteListRoute> {
            NoteListRoot(
                onNavigateToDetail = { navController.navigate(NoteDetailRoute(it)) }
            )
        }
        composable<NoteDetailRoute> { backStackEntry ->
            val route: NoteDetailRoute = backStackEntry.toRoute()
            NoteDetailRoot(
                noteId = route.noteId,
                onNavigateToEditor = onNavigateToEditor
            )
        }
    }
}

Wiring in :app

All feature nav graphs are assembled in one place:

// :app
NavHost(navController, startDestination = NoteListRoute) {
    notesGraph(
        navController = navController,
        onNavigateToEditor = { navController.navigate(EditorRoute(it)) }
    )
    editorGraph(navController)
}

Cross-feature navigation is always expressed as a lambda callback — never by importing a route from another feature module.

Passing Arguments

For simple scalar arguments, use @Serializable data class routes:

@Serializable data class NoteDetailRoute(val noteId: String)
 
// Navigate
navController.navigate(NoteDetailRoute(noteId = "abc123"))
 
// Receive
composable<NoteDetailRoute> { backStackEntry ->
    val route: NoteDetailRoute = backStackEntry.toRoute()
    // route.noteId available here
}

Avoid passing complex objects via navigation — pass IDs and load data in the destination ViewModel.

Naming Conventions

Checklist: Adding Navigation to a New Feature

• Define @Serializable route objects for each screen in feature:presentation
• Add feature nav graph function (NavGraphBuilder.<feature>Graph(...))
• Pass NavController for intra-feature navigation
• Expose cross-feature destinations as lambda callbacks (not direct route imports)
• Wire nav graph and cross-feature callbacks in :app's NavHost