android/app/src/main/java/com/fabledsword/minstrel/MainActivity.kt

@@ -10,6 +10,7 @@ import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -17,27 +18,34 @@ import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.navigation.compose.rememberNavController
 import com.fabledsword.minstrel.auth.ui.AuthGateViewModel
+import com.fabledsword.minstrel.nav.DetailSeedCache
+import com.fabledsword.minstrel.nav.LocalDetailSeedCache
 import com.fabledsword.minstrel.nav.MinstrelNavGraph
 import com.fabledsword.minstrel.theme.MinstrelTheme
 import com.fabledsword.minstrel.theme.ThemePreferenceViewModel
 import dagger.hilt.android.AndroidEntryPoint
+import javax.inject.Inject
 
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {
+    @Inject lateinit var seedCache: DetailSeedCache
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
-        setContent { App() }
+        setContent { App(seedCache = seedCache) }
     }
 }
 
 @Composable
 private fun App(
+    seedCache: DetailSeedCache,
     themeVm: ThemePreferenceViewModel = hiltViewModel(),
     gate: AuthGateViewModel = hiltViewModel(),
 ) {
     val theme by themeVm.themeMode.collectAsStateWithLifecycle()
     MinstrelTheme(darkOverride = theme.toDarkOverride()) {
+        CompositionLocalProvider(LocalDetailSeedCache provides seedCache) {
             val startDestination by gate.startDestination.collectAsStateWithLifecycle()
             val resolved = startDestination
             if (resolved == null) {
@@ -57,6 +65,7 @@ private fun App(
             }
         }
     }
+}
 
 @Composable
 private fun BootSplash() {

android/app/src/main/java/com/fabledsword/minstrel/library/ui/AlbumDetailScreen.kt

@@ -95,7 +95,7 @@ fun AlbumDetailScreen(
             modifier = Modifier.fillMaxSize().padding(inner),
         ) {
             when (val s = state) {
-                AlbumDetailUiState.Loading -> LoadingCentered()
+                is AlbumDetailUiState.Loading -> LoadingCentered()
                 is AlbumDetailUiState.Error -> EmptyState(
                     title = "Couldn't load album",
                     body = s.message,
@@ -125,7 +125,8 @@ fun AlbumDetailScreen(
 
 private fun titleFor(state: AlbumDetailUiState): String = when (state) {
     is AlbumDetailUiState.Success -> state.detail.album.title
-    else -> "Album"
+    is AlbumDetailUiState.Loading -> state.seed?.title ?: "Album"
+    is AlbumDetailUiState.Error -> "Album"
 }
 
 @Composable

android/app/src/main/java/com/fabledsword/minstrel/library/ui/AlbumDetailViewModel.kt

@@ -7,7 +7,9 @@ import androidx.navigation.toRoute
 import com.fabledsword.minstrel.library.data.LibraryRepository
 import com.fabledsword.minstrel.likes.data.LikesRepository
 import com.fabledsword.minstrel.models.AlbumDetailRef
+import com.fabledsword.minstrel.models.AlbumRef
 import com.fabledsword.minstrel.nav.AlbumDetail
+import com.fabledsword.minstrel.nav.DetailSeedCache
 import com.fabledsword.minstrel.player.PlayerController
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
@@ -23,7 +25,7 @@ import javax.inject.Inject
 private const val SHARE_STOP_TIMEOUT_MS = 5_000L
 
 sealed interface AlbumDetailUiState {
-    data object Loading : AlbumDetailUiState
+    data class Loading(val seed: AlbumRef? = null) : AlbumDetailUiState
     data class Success(val detail: AlbumDetailRef) : AlbumDetailUiState
     data class Error(val message: String) : AlbumDetailUiState
 }
@@ -33,13 +35,15 @@ class AlbumDetailViewModel @Inject constructor(
     private val repository: LibraryRepository,
     private val likes: LikesRepository,
     private val player: PlayerController,
+    private val seedCache: DetailSeedCache,
     savedStateHandle: SavedStateHandle,
 ) : ViewModel() {
 
     private val route: AlbumDetail = savedStateHandle.toRoute()
     val albumId: String = route.id
 
-    private val internal = MutableStateFlow<AlbumDetailUiState>(AlbumDetailUiState.Loading)
+    private val internal =
+        MutableStateFlow<AlbumDetailUiState>(AlbumDetailUiState.Loading())
     val uiState: StateFlow<AlbumDetailUiState> = internal.asStateFlow()
 
     val albumLiked: StateFlow<Boolean> =
@@ -64,7 +68,12 @@ class AlbumDetailViewModel @Inject constructor(
     }
 
     fun refresh(): Job = viewModelScope.launch {
-        internal.value = AlbumDetailUiState.Loading
+        val carried = when (val cur = internal.value) {
+            is AlbumDetailUiState.Loading -> cur.seed
+            is AlbumDetailUiState.Success -> cur.detail.album
+            is AlbumDetailUiState.Error -> null
+        }
+        internal.value = AlbumDetailUiState.Loading(carried ?: seedCache.peekAlbum(albumId))
         try {
             val detail = repository.refreshAlbumDetail(albumId)
             internal.value = AlbumDetailUiState.Success(detail)

android/app/src/main/java/com/fabledsword/minstrel/library/ui/ArtistDetailScreen.kt

@@ -76,7 +76,7 @@ fun ArtistDetailScreen(
             modifier = Modifier.fillMaxSize().padding(inner),
         ) {
             when (val s = state) {
-                ArtistDetailUiState.Loading -> LoadingCentered()
+                is ArtistDetailUiState.Loading -> LoadingCentered()
                 is ArtistDetailUiState.Error -> EmptyState(
                     title = "Couldn't load artist",
                     body = s.message,
@@ -98,7 +98,8 @@ fun ArtistDetailScreen(
 
 private fun titleFor(state: ArtistDetailUiState): String = when (state) {
     is ArtistDetailUiState.Success -> state.detail.artist.name
-    else -> "Artist"
+    is ArtistDetailUiState.Loading -> state.seed?.name ?: "Artist"
+    is ArtistDetailUiState.Error -> "Artist"
 }
 
 @Composable

android/app/src/main/java/com/fabledsword/minstrel/library/ui/ArtistDetailViewModel.kt

@@ -7,7 +7,9 @@ import androidx.navigation.toRoute
 import com.fabledsword.minstrel.library.data.LibraryRepository
 import com.fabledsword.minstrel.likes.data.LikesRepository
 import com.fabledsword.minstrel.models.ArtistDetailRef
+import com.fabledsword.minstrel.models.ArtistRef
 import com.fabledsword.minstrel.nav.ArtistDetail
+import com.fabledsword.minstrel.nav.DetailSeedCache
 import com.fabledsword.minstrel.player.PlayerController
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
@@ -22,7 +24,7 @@ import javax.inject.Inject
 private const val SHARE_STOP_TIMEOUT_MS = 5_000L
 
 sealed interface ArtistDetailUiState {
-    data object Loading : ArtistDetailUiState
+    data class Loading(val seed: ArtistRef? = null) : ArtistDetailUiState
     data class Success(val detail: ArtistDetailRef) : ArtistDetailUiState
     data class Error(val message: String) : ArtistDetailUiState
 }
@@ -32,13 +34,15 @@ class ArtistDetailViewModel @Inject constructor(
     private val repository: LibraryRepository,
     private val likes: LikesRepository,
     private val player: PlayerController,
+    private val seedCache: DetailSeedCache,
     savedStateHandle: SavedStateHandle,
 ) : ViewModel() {
 
     private val route: ArtistDetail = savedStateHandle.toRoute()
     val artistId: String = route.id
 
-    private val internal = MutableStateFlow<ArtistDetailUiState>(ArtistDetailUiState.Loading)
+    private val internal =
+        MutableStateFlow<ArtistDetailUiState>(ArtistDetailUiState.Loading())
     val uiState: StateFlow<ArtistDetailUiState> = internal.asStateFlow()
 
     val artistLiked: StateFlow<Boolean> =
@@ -61,7 +65,12 @@ class ArtistDetailViewModel @Inject constructor(
     }
 
     fun refresh(): Job = viewModelScope.launch {
-        internal.value = ArtistDetailUiState.Loading
+        val carried = when (val cur = internal.value) {
+            is ArtistDetailUiState.Loading -> cur.seed
+            is ArtistDetailUiState.Success -> cur.detail.artist
+            is ArtistDetailUiState.Error -> null
+        }
+        internal.value = ArtistDetailUiState.Loading(carried ?: seedCache.peekArtist(artistId))
         try {
             val detail = repository.refreshArtistDetail(artistId)
             internal.value = ArtistDetailUiState.Success(detail)

android/app/src/main/java/com/fabledsword/minstrel/library/widgets/AlbumCard.kt

@@ -27,12 +27,15 @@ import com.composables.icons.lucide.Disc3
 import com.composables.icons.lucide.Lucide
 import androidx.compose.material3.Icon
 import com.fabledsword.minstrel.models.AlbumRef
+import com.fabledsword.minstrel.nav.LocalDetailSeedCache
 import com.fabledsword.minstrel.theme.FabledSwordFlatTokens
 
 /**
  * One album tile. Mirrors the Flutter `AlbumCard` (~176dp wide, 144dp
  * square cover). Tap fires `onClick` — wired to `AlbumDetail` nav in
- * Phase 5.5.
+ * Phase 5.5. The tile stashes its `album` in [LocalDetailSeedCache]
+ * before firing onClick so the detail screen's AppBar renders title /
+ * cover / counts immediately without waiting for the fetch.
  */
 @Composable
 fun AlbumCard(
@@ -40,10 +43,14 @@ fun AlbumCard(
     onClick: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
+    val seedCache = LocalDetailSeedCache.current
     Surface(
         modifier = modifier
             .width(176.dp)
-            .clickable(onClick = onClick),
+            .clickable {
+                seedCache.stashAlbum(album)
+                onClick()
+            },
         color = Color.Transparent,
     ) {
         Column(modifier = Modifier.padding(horizontal = 8.dp)) {

android/app/src/main/java/com/fabledsword/minstrel/library/widgets/ArtistCard.kt

@@ -27,10 +27,13 @@ import coil3.compose.AsyncImage
 import com.composables.icons.lucide.Lucide
 import com.composables.icons.lucide.User
 import com.fabledsword.minstrel.models.ArtistRef
+import com.fabledsword.minstrel.nav.LocalDetailSeedCache
 
 /**
  * One artist tile. Circular cover; name centered beneath. Tap fires
- * `onClick` — wired to `ArtistDetail` nav in Phase 5.5.
+ * `onClick` — wired to `ArtistDetail` nav in Phase 5.5. Stashes the
+ * `artist` in [LocalDetailSeedCache] on click so the ArtistDetail
+ * AppBar renders the name before the fetch lands.
  */
 @Composable
 fun ArtistCard(
@@ -38,10 +41,14 @@ fun ArtistCard(
     onClick: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
+    val seedCache = LocalDetailSeedCache.current
     Surface(
         modifier = modifier
             .width(144.dp)
-            .clickable(onClick = onClick),
+            .clickable {
+                seedCache.stashArtist(artist)
+                onClick()
+            },
         color = Color.Transparent,
     ) {
         Column(

android/app/src/main/java/com/fabledsword/minstrel/nav/DetailSeedCache.kt

@@ -0,0 +1,51 @@
+package com.fabledsword.minstrel.nav
+
+import androidx.compose.runtime.staticCompositionLocalOf
+import com.fabledsword.minstrel.models.AlbumRef
+import com.fabledsword.minstrel.models.ArtistRef
+import com.fabledsword.minstrel.models.PlaylistRef
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * In-memory hand-off for detail-screen "seed" data — the lightweight
+ * Ref the caller already has when navigating to AlbumDetail /
+ * ArtistDetail / PlaylistDetail. The detail VM peeks the seed on
+ * init so the AppBar header (title / cover / counts) renders
+ * immediately, before the network round-trip completes.
+ *
+ * Mirrors Flutter's go_router `extra:` parameter pattern. Bounded
+ * per-bucket via insertion-order LRU so back/forward navigation
+ * doesn't grow unbounded.
+ */
+@Singleton
+class DetailSeedCache @Inject constructor() {
+    private val albums = lru<AlbumRef>(MAX_ENTRIES)
+    private val artists = lru<ArtistRef>(MAX_ENTRIES)
+    private val playlists = lru<PlaylistRef>(MAX_ENTRIES)
+
+    @Synchronized fun stashAlbum(ref: AlbumRef) { albums[ref.id] = ref }
+    @Synchronized fun stashArtist(ref: ArtistRef) { artists[ref.id] = ref }
+    @Synchronized fun stashPlaylist(ref: PlaylistRef) { playlists[ref.id] = ref }
+
+    @Synchronized fun peekAlbum(id: String): AlbumRef? = albums[id]
+    @Synchronized fun peekArtist(id: String): ArtistRef? = artists[id]
+    @Synchronized fun peekPlaylist(id: String): PlaylistRef? = playlists[id]
+
+    private companion object {
+        private const val MAX_ENTRIES = 32
+        private fun <V> lru(max: Int): MutableMap<String, V> =
+            object : LinkedHashMap<String, V>(max, 0.75f, true) {
+                override fun removeEldestEntry(eldest: Map.Entry<String, V>) = size > max
+            }
+    }
+}
+
+/**
+ * CompositionLocal carrying the app's [DetailSeedCache]. Provided
+ * at the [com.fabledsword.minstrel.MainActivity] root so any screen
+ * can stash a seed before calling `navController.navigate(...)`.
+ */
+val LocalDetailSeedCache = staticCompositionLocalOf<DetailSeedCache> {
+    error("DetailSeedCache not provided — wrap content in CompositionLocalProvider")
+}

android/app/src/main/java/com/fabledsword/minstrel/playlists/ui/PlaylistDetailScreen.kt

@@ -65,6 +65,7 @@ import com.fabledsword.minstrel.models.PlaylistTrackRef
 import com.fabledsword.minstrel.models.TrackRef
 import com.fabledsword.minstrel.nav.AlbumDetail
 import com.fabledsword.minstrel.nav.ArtistDetail
+import com.fabledsword.minstrel.nav.DetailSeedCache
 import com.fabledsword.minstrel.nav.PlaylistDetail
 import com.fabledsword.minstrel.player.PlayerController
 import com.fabledsword.minstrel.likes.data.LikesRepository
@@ -98,7 +99,7 @@ private const val SHARE_STOP_TIMEOUT_MS = 5_000L
 // ─── State ───────────────────────────────────────────────────────────
 
 sealed interface PlaylistDetailUiState {
-    data object Loading : PlaylistDetailUiState
+    data class Loading(val seed: PlaylistRef? = null) : PlaylistDetailUiState
     data class Success(val detail: PlaylistDetailRef) : PlaylistDetailUiState
     data class Error(val message: String) : PlaylistDetailUiState
 }
@@ -111,13 +112,15 @@ class PlaylistDetailViewModel @Inject constructor(
     private val likes: LikesRepository,
     private val player: PlayerController,
     private val eventsStream: EventsStream,
+    private val seedCache: DetailSeedCache,
     savedStateHandle: SavedStateHandle,
 ) : ViewModel() {
 
     private val route: PlaylistDetail = savedStateHandle.toRoute()
     val playlistId: String = route.id
 
-    private val internal = MutableStateFlow<PlaylistDetailUiState>(PlaylistDetailUiState.Loading)
+    private val internal =
+        MutableStateFlow<PlaylistDetailUiState>(PlaylistDetailUiState.Loading())
     val uiState: StateFlow<PlaylistDetailUiState> = internal.asStateFlow()
 
     /**
@@ -178,7 +181,14 @@ class PlaylistDetailViewModel @Inject constructor(
 
     fun refresh(): Job = viewModelScope.launch {
         try {
-            internal.value = PlaylistDetailUiState.Loading
+            val carried = when (val cur = internal.value) {
+                is PlaylistDetailUiState.Loading -> cur.seed
+                is PlaylistDetailUiState.Success -> cur.detail.playlist
+                is PlaylistDetailUiState.Error -> null
+            }
+            internal.value = PlaylistDetailUiState.Loading(
+                carried ?: seedCache.peekPlaylist(playlistId),
+            )
             val detail = repository.refreshDetail(playlistId)
             internal.value = PlaylistDetailUiState.Success(detail)
         } catch (
@@ -287,7 +297,7 @@ private fun PlaylistDetailContent(
     navController: NavHostController,
 ) {
     when (state) {
-        PlaylistDetailUiState.Loading -> LoadingCentered()
+        is PlaylistDetailUiState.Loading -> LoadingCentered()
         is PlaylistDetailUiState.Error -> ErrorBlock(state.message, viewModel::refresh)
         is PlaylistDetailUiState.Success -> {
             val likedTrackIds by viewModel.likedTrackIds.collectAsState()
@@ -314,7 +324,8 @@ private fun PlaylistDetailContent(
 
 private fun currentTitle(state: PlaylistDetailUiState): String = when (state) {
     is PlaylistDetailUiState.Success -> state.detail.playlist.name
-    else -> "Playlist"
+    is PlaylistDetailUiState.Loading -> state.seed?.name ?: "Playlist"
+    is PlaylistDetailUiState.Error -> "Playlist"
 }
 
 // ─── Body composables ────────────────────────────────────────────────

android/app/src/main/java/com/fabledsword/minstrel/playlists/widgets/PlaylistCard.kt

@@ -26,6 +26,7 @@ import coil3.compose.AsyncImage
 import com.composables.icons.lucide.ListMusic
 import com.composables.icons.lucide.Lucide
 import com.fabledsword.minstrel.models.PlaylistRef
+import com.fabledsword.minstrel.nav.LocalDetailSeedCache
 import com.fabledsword.minstrel.theme.FabledSwordFlatTokens
 
 /**
@@ -43,10 +44,14 @@ fun PlaylistCard(
     onClick: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
+    val seedCache = LocalDetailSeedCache.current
     Surface(
         modifier = modifier
             .width(176.dp)
-            .clickable(onClick = onClick),
+            .clickable {
+                seedCache.stashPlaylist(playlist)
+                onClick()
+            },
         color = Color.Transparent,
     ) {
         Column(modifier = Modifier.padding(horizontal = 8.dp)) {