Refactor navigation state management

This commit refactors the navigation state management by renaming `NiaNavigatorState` to `NavigationState` to make it more generic.

Specific changes include:
- Renamed `NiaNavigatorState` to `NavigationState`.
- Renamed `NiaNavigatorProvider` to `NavigationStateProvider`.
- Updated all usages of the renamed classes, including `NiaNavigator`, `NiaBackStackViewModel`, and various tests.
- Replaced the `getEntries()` extension function with `toEntries()`.
- Added numerous TODOs to identify areas for future improvement, such as removing dependencies on `SavedStateHandle` for navigation state, simplifying event handling in ViewModels, and documenting the new navigation components.

app/src/main/kotlin/com/google/samples/apps/nowinandroid/MainActivity.kt

@@ -85,6 +85,8 @@ class MainActivity : ComponentActivity() {
 
     private val viewModel: MainActivityViewModel by viewModels()
 
+
+    // TODO: This isn't used
     private val backStackViewModel: NiaBackStackViewModel by viewModels()
 
     override fun onCreate(savedInstanceState: Bundle?) {

app/src/main/kotlin/com/google/samples/apps/nowinandroid/di/NavigationStateProvider.kt

@@ -17,7 +17,7 @@
 package com.google.samples.apps.nowinandroid.di
 
 import com.google.samples.apps.nowinandroid.core.navigation.NiaNavKey
-import com.google.samples.apps.nowinandroid.core.navigation.NiaNavigatorState
+import com.google.samples.apps.nowinandroid.core.navigation.NavigationState
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination
 import dagger.Module
 import dagger.Provides
@@ -28,15 +28,19 @@ import kotlinx.serialization.modules.SerializersModule
 import kotlinx.serialization.modules.polymorphic
 import javax.inject.Singleton
 
+// TODO: Rename to `NiaNavigationStateProvider`
+//  Does this even need to be injected? Can't we just instantiate it directly using `rememberNavigationState`?
 @Module
 @InstallIn(SingletonComponent::class)
-object NiaNavigatorProvider {
+object NavigationStateProvider {
     @Provides
     @Singleton
-    fun providerNiaNavigatorState(): NiaNavigatorState =
-        NiaNavigatorState(
+    fun provideNavigationState(): NavigationState =
+        NavigationState(
             startKey = TopLevelDestination.FOR_YOU.key,
         )
+
+// TODO: Remove commented out code
 //
 //    @Provides
 //    @Singleton

app/src/main/kotlin/com/google/samples/apps/nowinandroid/navigation/NiaNavDisplay.kt

@@ -23,8 +23,7 @@ import androidx.navigation3.runtime.EntryProviderScope
 import androidx.navigation3.ui.NavDisplay
 import com.google.samples.apps.nowinandroid.core.navigation.NiaNavKey
 import com.google.samples.apps.nowinandroid.core.navigation.NiaNavigator
-import com.google.samples.apps.nowinandroid.core.navigation.getEntries
-import kotlin.collections.plus
+import com.google.samples.apps.nowinandroid.core.navigation.toEntries
 
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
 @Composable
@@ -33,7 +32,7 @@ fun NiaNavDisplay(
     entryProviderBuilders: Set<EntryProviderScope<NiaNavKey>.() -> Unit>,
 ) {
     val listDetailStrategy = rememberListDetailSceneStrategy<NiaNavKey>()
-    val entries = niaNavigator.navigatorState.getEntries(entryProviderBuilders)
+    val entries = niaNavigator.navigationState.toEntries(entryProviderBuilders)
     NavDisplay(
         entries = entries,
         sceneStrategy = listDetailStrategy,

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -241,6 +241,11 @@ internal fun NiaApp(
                         },
                     ),
                 ) {
+
+                    // Instantiate the NavigationState here
+
+
+
                     NiaNavDisplay(
                         niaNavigator = appState.niaNavigator,
                         entryProviderBuilders = entryProviderBuilders,

app/src/main/kotlin/com/google/samples/apps/nowinandroid/ui/NiaAppState.kt

@@ -71,7 +71,7 @@ class NiaAppState(
     timeZoneMonitor: TimeZoneMonitor,
 ) {
     val currentTopLevelDestination: TopLevelDestination?
-        @Composable get() = TopLevelDestinations[niaNavigator.navigatorState.currentTopLevelKey]
+        @Composable get() = TopLevelDestinations[niaNavigator.navigationState.currentTopLevelKey]
 
     val isOffline = networkMonitor.isOnline
         .map(Boolean::not)

core/navigation/src/androidTest/kotlin/com/google/samples/apps/nowinandroid/core/navigation/NiaBackStackViewModelTest.kt

@@ -48,7 +48,7 @@ class NiaBackStackViewModelTest {
 
     private fun createViewModel() = NiaBackStackViewModel(
         savedStateHandle = SavedStateHandle(),
-        niaNavigatorState = NiaNavigatorState(TestStartKey),
+        navigationState = NavigationState(TestStartKey),
         serializersModules = serializersModules,
     )
 
@@ -67,7 +67,7 @@ class NiaBackStackViewModelTest {
     fun testNonTopLevelKeySaved() {
         val viewModel = createViewModel()
         rule.setContent {
-            val navigator = remember { NiaNavigator(viewModel.niaNavigatorState) }
+            val navigator = remember { NiaNavigator(viewModel.navigationState) }
             navigator.navigate(TestKeyFirst)
         }
         assertThat(viewModel.backStackMap.size).isEqualTo(1)
@@ -80,7 +80,7 @@ class NiaBackStackViewModelTest {
     fun testTopLevelKeySaved() {
         val viewModel = createViewModel()
         rule.setContent {
-            val navigator = remember { NiaNavigator(viewModel.niaNavigatorState) }
+            val navigator = remember { NiaNavigator(viewModel.navigationState) }
 
             navigator.navigate(TestKeyFirst)
             navigator.navigate(TestTopLevelKeyFirst)
@@ -101,7 +101,7 @@ class NiaBackStackViewModelTest {
     fun testMultiStacksSaved() {
         val viewModel = createViewModel()
         rule.setContent {
-            val navigator = remember { NiaNavigator(viewModel.niaNavigatorState) }
+            val navigator = remember { NiaNavigator(viewModel.navigationState) }
             navigator.navigate(TestKeyFirst)
             navigator.navigate(TestTopLevelKeyFirst)
             navigator.navigate(TestKeySecond)
@@ -122,7 +122,7 @@ class NiaBackStackViewModelTest {
     fun testPopSaved() {
         val viewModel = createViewModel()
         rule.setContent {
-            val navigator = remember { NiaNavigator(viewModel.niaNavigatorState) }
+            val navigator = remember { NiaNavigator(viewModel.navigationState) }
 
             navigator.navigate(TestKeyFirst)
 
@@ -144,14 +144,14 @@ class NiaBackStackViewModelTest {
     fun testRestore() {
         lateinit var scenario: ViewModelScenario<NiaBackStackViewModel>
         lateinit var navigator: NiaNavigator
-        lateinit var navigatorState: NiaNavigatorState
+        lateinit var navigatorState: NavigationState
         rule.setContent {
-            navigatorState = remember { NiaNavigatorState(TestStartKey) }
+            navigatorState = remember { NavigationState(TestStartKey) }
             navigator = remember { NiaNavigator(navigatorState) }
             scenario = viewModelScenario {
                 NiaBackStackViewModel(
                     savedStateHandle = createSavedStateHandle(),
-                    niaNavigatorState = navigatorState,
+                    navigationState = navigatorState,
                     serializersModules = serializersModules,
                 )
             }
@@ -181,14 +181,14 @@ class NiaBackStackViewModelTest {
     fun testRestoreMultiStacks() {
         lateinit var scenario: ViewModelScenario<NiaBackStackViewModel>
         lateinit var navigator: NiaNavigator
-        lateinit var navigatorState: NiaNavigatorState
+        lateinit var navigatorState: NavigationState
         rule.setContent {
-            navigatorState = remember { NiaNavigatorState(TestStartKey) }
+            navigatorState = remember { NavigationState(TestStartKey) }
             navigator = remember { NiaNavigator(navigatorState) }
             scenario = viewModelScenario {
                 NiaBackStackViewModel(
                     savedStateHandle = createSavedStateHandle(),
-                    niaNavigatorState = navigatorState,
+                    navigationState = navigatorState,
                     serializersModules = serializersModules,
                 )
             }

core/navigation/src/main/kotlin/com/google/samples/apps/nowinandroid/core/navigation/NiaBackStackViewModel.kt

@@ -33,10 +33,16 @@ import kotlinx.serialization.modules.SerializersModule
 import kotlinx.serialization.serializer
 import javax.inject.Inject
 
+/**
+ * TODO: I'm not sure why this needs to be a ViewModel - why can't it be a plain state holder that
+ *  is scoped to `NiaAppState`?
+ *  https://github.com/android/nav3-recipes/blob/main/app/src/main/java/com/example/nav3recipes/multiplestacks/NavigationState.kt#L71
+ *
+ */
 @HiltViewModel
 class NiaBackStackViewModel @Inject constructor(
     savedStateHandle: SavedStateHandle,
-    val niaNavigatorState: NiaNavigatorState,
+    val navigationState: NavigationState,
     serializersModules: SerializersModule,
 ) : ViewModel() {
 
@@ -63,9 +69,9 @@ class NiaBackStackViewModel @Inject constructor(
 
     init {
         if (backStackMap.isNotEmpty()) {
-            //    Restore backstack from saved state handle if not emtpy
+            // Restore backstack from saved state handle if not empty
             @Suppress("UNCHECKED_CAST")
-            niaNavigatorState.restore(
+            navigationState.restore(
                 activeTopLeveLKeys,
                 backStackMap as LinkedHashMap<NiaNavKey, SnapshotStateList<NiaNavKey>>,
             )
@@ -74,8 +80,8 @@ class NiaBackStackViewModel @Inject constructor(
         // Start observing changes to the backStack and save backStack whenever it updates
         viewModelScope.launch {
             snapshotFlow {
-                activeTopLeveLKeys = niaNavigatorState.activeTopLeveLKeys.toList()
-                backStackMap = niaNavigatorState.backStacks
+                activeTopLeveLKeys = navigationState.activeTopLeveLKeys.toList()
+                backStackMap = navigationState.backStacks
             }.collect()
         }
     }

core/navigation/src/main/kotlin/com/google/samples/apps/nowinandroid/core/navigation/NiaNavigator.kt

@@ -34,7 +34,8 @@ import org.jetbrains.annotations.VisibleForTesting
 import javax.inject.Inject
 import kotlin.collections.plus
 
-class NiaNavigatorState(
+// TODO: Consider changing this to `NiaNavigationState`
+class NavigationState(
     internal val startKey: NiaNavKey,
 ) {
     internal var backStacks: MutableMap<NiaNavKey, SnapshotStateList<NiaNavKey>> =
@@ -51,7 +52,7 @@ class NiaNavigatorState(
     val currentBackStack: List<NiaNavKey>
         get() = activeTopLeveLKeys.fold(mutableListOf()) { list, topLevelKey ->
             list.apply {
-                addAll(backStacks[topLevelKey]!!)
+                addAll(backStacks[topLevelKey] ?: error("No back stack found for $topLevelKey"))
             }
         }
 
@@ -76,13 +77,18 @@ class NiaNavigatorState(
     }
 }
 
-// https://github.com/android/nowinandroid/issues/1934
+/**
+ * TODO: Document this
+ */
 class NiaNavigator @Inject constructor(
-    val navigatorState: NiaNavigatorState,
+    val navigationState: NavigationState,
 ) {
+    // TODO: I wonder if it'd be simpler to have separate methods
+    //  for navigating to a graph and navigating to a key. If the key is on a separate graph then
+    //  navigate to that graph first.
     fun navigate(key: NiaNavKey) {
         val currentActiveSubStacks = linkedSetOf<NiaNavKey>()
-        navigatorState.apply {
+        navigationState.apply {
             currentActiveSubStacks.addAll(activeTopLeveLKeys)
             when {
                 // top level singleTop -> clear substack
@@ -120,7 +126,7 @@ class NiaNavigator @Inject constructor(
     }
 
     fun pop() {
-        navigatorState.apply {
+        navigationState.apply {
             val currentSubstack = backStacks[currentTopLevelKey]!!
             if (currentSubstack.size == 1) {
                 // if current sub-stack only has one key, remove the sub-stack from the map
@@ -134,12 +140,17 @@ class NiaNavigator @Inject constructor(
     }
 }
 
+// TODO: I wonder if removing this would remove the need for the serializers modules
 interface NiaNavKey {
     val isTopLevel: Boolean
 }
 
+/**
+ * Convert the navigation state to `NavEntry`s that can be displayed by a `NavDisplay`
+ */
 @Composable
-public fun NiaNavigatorState.getEntries(
+fun NavigationState.toEntries(
+    // TODO: Might be better to pass this in fully constructed
     entryProviderBuilders: Set<EntryProviderScope<NiaNavKey>.() -> Unit>,
 ): List<NavEntry<NiaNavKey>> =
     activeTopLeveLKeys.fold(emptyList()) { entries, topLevelKey ->

core/navigation/src/test/kotlin/com/google/samples/apps/nowinandroid/core/navigation/NiaNavigatorStateTest.kt

@@ -24,49 +24,49 @@ import kotlin.test.assertFailsWith
 
 class NiaNavigatorStateTest {
 
-    private lateinit var niaNavigatorState: NiaNavigatorState
+    private lateinit var navigationState: NavigationState
     private lateinit var niaNavigator: NiaNavigator
 
     @Before
     fun setup() {
-        niaNavigatorState = NiaNavigatorState(TestStartKey)
-        niaNavigator = NiaNavigator(niaNavigatorState)
+        navigationState = NavigationState(TestStartKey)
+        niaNavigator = NiaNavigator(navigationState)
     }
 
     @Test
     fun testStartKey() {
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestStartKey)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
     fun testNavigate() {
         niaNavigator.navigate(TestKeyFirst)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeyFirst)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeyFirst)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
     fun testNavigateTopLevel() {
         niaNavigator.navigate(TestTopLevelKey)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestTopLevelKey)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
     }
 
     @Test
     fun testNavigateSingleTop() {
         niaNavigator.navigate(TestKeyFirst)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
         ).inOrder()
 
         niaNavigator.navigate(TestKeyFirst)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
         ).inOrder()
@@ -77,7 +77,7 @@ class NiaNavigatorStateTest {
         niaNavigator.navigate(TestTopLevelKey)
         niaNavigator.navigate(TestKeyFirst)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestTopLevelKey,
             TestKeyFirst,
@@ -85,7 +85,7 @@ class NiaNavigatorStateTest {
 
         niaNavigator.navigate(TestTopLevelKey)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestTopLevelKey,
         ).inOrder()
@@ -95,13 +95,13 @@ class NiaNavigatorStateTest {
     fun testSubStack() {
         niaNavigator.navigate(TestKeyFirst)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeyFirst)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeyFirst)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
 
         niaNavigator.navigate(TestKeySecond)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeySecond)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeySecond)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
@@ -109,33 +109,33 @@ class NiaNavigatorStateTest {
         // add to start stack
         niaNavigator.navigate(TestKeyFirst)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeyFirst)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeyFirst)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
 
         // navigate to new top level
         niaNavigator.navigate(TestTopLevelKey)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestTopLevelKey)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
 
         // add to new stack
         niaNavigator.navigate(TestKeySecond)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeySecond)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeySecond)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
 
         // go back to start stack
         niaNavigator.navigate(TestStartKey)
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeyFirst)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeyFirst)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
     fun testRestore() {
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(TestStartKey)
+        assertThat(navigationState.currentBackStack).containsExactly(TestStartKey)
 
-        niaNavigatorState.restore(
+        navigationState.restore(
             listOf(TestStartKey, TestTopLevelKey),
             linkedMapOf(
                 TestStartKey to mutableStateListOf(TestStartKey, TestKeyFirst),
@@ -143,15 +143,15 @@ class NiaNavigatorStateTest {
             ),
         )
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
             TestTopLevelKey,
             TestKeySecond,
         ).inOrder()
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeySecond)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeySecond)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
     }
 
     @Test
@@ -159,7 +159,7 @@ class NiaNavigatorStateTest {
         niaNavigator.navigate(TestKeyFirst)
         niaNavigator.navigate(TestKeySecond)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
             TestKeySecond,
@@ -167,13 +167,13 @@ class NiaNavigatorStateTest {
 
         niaNavigator.pop()
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
         ).inOrder()
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeyFirst)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeyFirst)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
@@ -181,25 +181,25 @@ class NiaNavigatorStateTest {
         niaNavigator.navigate(TestKeyFirst)
         niaNavigator.navigate(TestTopLevelKey)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
             TestTopLevelKey,
         ).inOrder()
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestTopLevelKey)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestTopLevelKey)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestTopLevelKey)
 
         // remove TopLevel
         niaNavigator.pop()
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
         ).inOrder()
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestKeyFirst)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestKeyFirst)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
@@ -207,7 +207,7 @@ class NiaNavigatorStateTest {
         niaNavigator.navigate(TestKeyFirst)
         niaNavigator.navigate(TestKeySecond)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestKeyFirst,
             TestKeySecond,
@@ -216,12 +216,12 @@ class NiaNavigatorStateTest {
         niaNavigator.pop()
         niaNavigator.pop()
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
         ).inOrder()
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestStartKey)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test
@@ -238,7 +238,7 @@ class NiaNavigatorStateTest {
         niaNavigator.navigate(testTopLevelKeyTwo)
         niaNavigator.navigate(TestKeySecond)
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
             TestTopLevelKey,
             TestKeyFirst,
@@ -250,12 +250,12 @@ class NiaNavigatorStateTest {
             niaNavigator.pop()
         }
 
-        assertThat(niaNavigatorState.currentBackStack).containsExactly(
+        assertThat(navigationState.currentBackStack).containsExactly(
             TestStartKey,
         ).inOrder()
 
-        assertThat(niaNavigatorState.currentKey).isEqualTo(TestStartKey)
-        assertThat(niaNavigatorState.currentTopLevelKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentKey).isEqualTo(TestStartKey)
+        assertThat(navigationState.currentTopLevelKey).isEqualTo(TestStartKey)
     }
 
     @Test

feature/foryou/impl/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/foryou/impl/navigation/ForYouEntryProvider.kt

@@ -39,11 +39,16 @@ object ForYouEntryProvider {
     @IntoSet
     fun provideForYouEntryProviderBuilder(
         navigator: NiaNavigator,
-    ): EntryProviderScope<NiaNavKey>.() -> Unit = {
-        entry<ForYouRoute> {
-            ForYouScreen(
-                onTopicClick = navigator::navigateToTopic,
-            )
-        }
+    ): EntryProviderScope<NiaNavKey>.() -> Unit = forYouEntry(navigator)
+}
+
+fun forYouEntry(navigator: NiaNavigator): EntryProviderScope<NiaNavKey>.() -> Unit = {
+    entry<ForYouRoute> {
+        ForYouScreen(
+            onTopicClick = navigator::navigateToTopic,
+        )
     }
 }
+
+
+

feature/interests/impl/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/interests/impl/InterestsScreen.kt

@@ -47,6 +47,7 @@ fun InterestsScreen(
         uiState = uiState,
         followTopic = viewModel::followTopic,
         onTopicClick = {
+            // TODO: this violates SSOT, events should go through the ViewModel
             viewModel.onTopicClick(it)
             onTopicClick(it)
         },

feature/interests/impl/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/interests/impl/InterestsViewModel.kt

@@ -39,9 +39,12 @@ class InterestsViewModel @AssistedInject constructor(
     private val savedStateHandle: SavedStateHandle,
     val userDataRepository: UserDataRepository,
     getFollowableTopics: GetFollowableTopicsUseCase,
+    // TODO: see comment below
     @Assisted val key: InterestsRoute,
 ) : ViewModel() {
 
+    // TODO: this should no longer be necessary, the currently selected topic should be
+    //  available through the navigation state
     // Key used to save and retrieve the currently selected topic id from saved state.
     private val selectedTopicIdKey = "selectedTopicIdKey"
 
@@ -67,6 +70,8 @@ class InterestsViewModel @AssistedInject constructor(
     }
 
     fun onTopicClick(topicId: String?) {
+        // TODO: This should modify the navigation state directly rather than just updating the
+        //  savedStateHandle
         savedStateHandle[selectedTopicIdKey] = topicId
     }
 

feature/interests/impl/src/main/kotlin/com/google/samples/apps/nowinandroid/feature/interests/impl/navigation/InterestsEntryProvider.kt

@@ -52,7 +52,11 @@ object InterestsEntryProvider {
                 it.create(key)
             }
             InterestsScreen(
+                // TODO: This event should be provided by the ViewModel
                 onTopicClick = navigator::navigateToTopic,
+
+                // TODO: This should be dynamically calculated based on the rendering scene
+                //  See https://github.com/android/nav3-recipes/commit/488f4811791ca3ed7192f4fe3c86e7371b32ebdc#diff-374e02026cdd2f68057dd940f203dc4ba7319930b33e9555c61af7e072211cabR89
                 shouldHighlightSelectedTopic = false,
                 viewModel = viewModel,
             )

feature/interests/impl/src/test/kotlin/com/google/samples/apps/nowinandroid/interests/impl/InterestsListDetailScreenTest.kt

@@ -162,6 +162,7 @@ class InterestsListDetailScreenTest {
         composeTestRule.apply {
             setContent {
                 val backStackViewModel by composeTestRule.activity.viewModels<NiaBackStackViewModel>()
+                // TODO: This is broken
                 val backStack = backStackViewModel.niaNavigator.backStack
                 NiaTheme {
                     NavDisplay(