library: keep detail scroll positions across navigation

app/src/main/kotlin/com/subtracks/ui/library/AlbumDetailScreen.kt

@@ -67,9 +67,9 @@ fun AlbumDetailRoute(
     viewModel: AlbumDetailViewModel = koinViewModel(key = albumId) { parametersOf(albumId) },
     playbackController: PlaybackController = koinInject(),
 ) {
-    val album by viewModel.album.collectAsStateWithLifecycle(initialValue = null)
+    val album by viewModel.album.collectAsStateWithLifecycle()
-    val songs by viewModel.songs.collectAsStateWithLifecycle(initialValue = emptyList())
+    val songs by viewModel.songs.collectAsStateWithLifecycle()
-    val discs by viewModel.discs.collectAsStateWithLifecycle(initialValue = emptyList())
+    val discs by viewModel.discs.collectAsStateWithLifecycle()
     val downloads by viewModel.downloads.collectAsStateWithLifecycle()
     val downloadStatus by viewModel.downloadStatus.collectAsStateWithLifecycle()
     val offline by viewModel.offline.collectAsStateWithLifecycle()

app/src/main/kotlin/com/subtracks/ui/library/AlbumDetailViewModel.kt

@@ -15,7 +15,6 @@ import com.subtracks.data.repo.LibraryRepository
 import com.subtracks.data.repo.SourceRepository
 import com.subtracks.playback.PlaybackController
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.combine
@@ -35,13 +34,20 @@ class AlbumDetailViewModel(
 ) : ViewModel() {
     private val sourceId = libraryRepository.activeSourceId.filterNotNull()
 
-    val album: Flow<Album?> = sourceId.flatMapLatest { libraryRepository.album(it, albumId) }
+    val album: StateFlow<Album?> =
+        sourceId
+            .flatMapLatest { libraryRepository.album(it, albumId) }
+            .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)
 
-    val songs: Flow<List<Song>> =
+    val songs: StateFlow<List<Song>> =
         combine(sourceId, sourceRepository.offline) { id, offline -> id to offline }
             .flatMapLatest { (id, offline) -> libraryRepository.albumSongs(id, albumId, offline) }
+            .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())
 
-    val discs: Flow<List<Disc>> = sourceId.flatMapLatest { libraryRepository.albumDiscs(it, albumId) }
+    val discs: StateFlow<List<Disc>> =
+        sourceId
+            .flatMapLatest { libraryRepository.albumDiscs(it, albumId) }
+            .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())
 
     val downloads: StateFlow<Map<String, SongDownload>> = downloadRepository.states()
 

app/src/main/kotlin/com/subtracks/ui/library/ArtistDetailScreen.kt

@@ -191,9 +191,9 @@ fun ArtistDetailRoute(
     viewModel: ArtistDetailViewModel = koinViewModel(key = artistId) { parametersOf(artistId) },
     playbackController: PlaybackController = koinInject(),
 ) {
-    val artist by viewModel.artist.collectAsStateWithLifecycle(initialValue = null)
+    val artist by viewModel.artist.collectAsStateWithLifecycle()
-    val artistName by viewModel.artistName.collectAsStateWithLifecycle(initialValue = null)
+    val artistName by viewModel.artistName.collectAsStateWithLifecycle()
-    val albums by viewModel.albums.collectAsStateWithLifecycle(initialValue = null)
+    val albums by viewModel.albums.collectAsStateWithLifecycle()
     val bioSnapshots =
         remember(viewModel) {
             viewModel.artistBio.map { BioSnapshot(known = true, present = it != null, biography = it?.biography) }

app/src/main/kotlin/com/subtracks/ui/library/ArtistDetailViewModel.kt

@@ -17,7 +17,6 @@ import com.subtracks.ui.components.ArtistArt
 import com.subtracks.ui.components.artistArt
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.Job
-import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
@@ -27,7 +26,6 @@ import kotlinx.coroutines.flow.filterNotNull
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 
@@ -41,23 +39,27 @@ class ArtistDetailViewModel(
 ) : ViewModel() {
     private val sourceId = libraryRepository.activeSourceId.filterNotNull()
 
-    val artist: Flow<Artist?> = sourceId.flatMapLatest { libraryRepository.artist(it, artistId) }
+    val artist: StateFlow<Artist?> =
+        sourceId
+            .flatMapLatest { libraryRepository.artist(it, artistId) }
+            .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)
 
-    val artistName: Flow<String?> =
+    val artistName: StateFlow<String?> =
-        sourceId.flatMapLatest { id ->
+        sourceId
+            .flatMapLatest { id ->
                 combine(
                     libraryRepository.artist(id, artistId),
                     libraryRepository.artistName(id, artistId),
                 ) { loaded, fromSongs -> loaded?.name?.takeIf { it.isNotBlank() } ?: fromSongs }
-        }
+            }.stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)
 
     val offline: StateFlow<Boolean> = sourceRepository.offline
 
-    val albums: Flow<ArtistAlbums?> =
+    val albums: StateFlow<ArtistAlbums?> =
         combine(sourceId, sourceRepository.offline) { id, offline -> id to offline }
             .flatMapLatest { (id, offline) -> libraryRepository.artistAlbums(id, artistId, offline) }
             .map<ArtistAlbums, ArtistAlbums?> { it }
-            .onStart { emit(null) }
+            .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)
 
     val downloadStatus: StateFlow<ListDownloadStatus> =
         sourceId
@@ -69,7 +71,10 @@ class ArtistDetailViewModel(
             .flatMapLatest { downloadRepository.statuses(it, DownloadList.Album) }
             .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyMap())
 
-    val artistBio: Flow<ArtistBio?> = sourceId.flatMapLatest { libraryRepository.artistBio(it, artistId) }
+    val artistBio: StateFlow<ArtistBio?> =
+        sourceId
+            .flatMapLatest { libraryRepository.artistBio(it, artistId) }
+            .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)
 
     private val _bioLoading = MutableStateFlow(true)
     val bioLoading: StateFlow<Boolean> = _bioLoading