refactor(android): extract asCacheFirstStateFlow helper (DRY 3d)

Five cache-first ViewModels all ended their flow pipeline with:

    .catch { e -> emit(UiState.Error(ErrorCopy.fromThrowable(e))) }
    .stateIn(viewModelScope,
             SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
             UiState.Loading)

plus a per-file private const for the 5_000L share-stop timeout.

Extract to a single Flow<UiState<T>> -> StateFlow<UiState<T>> extension
in shared/CacheFirstStateFlow.kt; migrate Library, PlaylistsList,
LikedTab, AddToPlaylist, and Home VMs. Each VM drops the catch +
stateIn + ErrorCopy + SharingStarted imports + the local constant.

AddToPlaylistVM keeps its onStart { refresh; emit Loading } block
in front of the helper -- that re-emit is intentional UX for sheet
re-opens past the 5s subscriber timeout.

android/app/src/main/java/com/fabledsword/minstrel/home/ui/HomeScreen.kt

@@ -47,7 +47,6 @@ import com.composables.icons.lucide.Heart
 import com.composables.icons.lucide.History
 import com.composables.icons.lucide.Lucide
 import com.composables.icons.lucide.Music
-import com.fabledsword.minstrel.api.ErrorCopy
 import com.fabledsword.minstrel.home.data.HomeRepository
 import com.fabledsword.minstrel.library.widgets.AlbumCard
 import com.fabledsword.minstrel.library.widgets.ArtistCard
@@ -66,6 +65,7 @@ import com.fabledsword.minstrel.playlists.widgets.OfflinePoolCard
 import com.fabledsword.minstrel.playlists.widgets.PlaylistCard
 import com.fabledsword.minstrel.playlists.widgets.PlaylistPlaceholderCard
 import com.fabledsword.minstrel.shared.UiState
+import com.fabledsword.minstrel.shared.asCacheFirstStateFlow
 import com.fabledsword.minstrel.shared.widgets.EmptyState
 import com.fabledsword.minstrel.shared.widgets.HorizontalScrollRow
 import com.fabledsword.minstrel.shared.widgets.MinstrelTopAppBar
@@ -81,7 +81,6 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
-import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.receiveAsFlow
@@ -196,11 +195,8 @@ class HomeViewModel @Inject constructor(
         status.join()
     }
 
-    val uiState: StateFlow<UiState<HomeSections>> = combineHomeFlows().stateIn(
-        scope = viewModelScope,
-        started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
-        initialValue = UiState.Loading,
-    )
+    val uiState: StateFlow<UiState<HomeSections>> =
+        combineHomeFlows().asCacheFirstStateFlow(viewModelScope)
 
     /**
      * Five home-section flows merged into the sections struct without
@@ -229,7 +225,7 @@ class HomeViewModel @Inject constructor(
         observeHomeSections().combine(playlistsRepository.observeAll()) { sections, playlists ->
             val merged = sections.copy(playlists = playlists)
             if (merged.isAllEmpty) UiState.Empty else UiState.Success(merged)
-        }.catch { e -> emit(UiState.Error(ErrorCopy.fromThrowable(e))) }
+        }
 }
 
 // ─── Screen ──────────────────────────────────────────────────────────

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

@@ -2,22 +2,17 @@ package com.fabledsword.minstrel.library.ui
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
-import com.fabledsword.minstrel.api.ErrorCopy
 import com.fabledsword.minstrel.cache.sync.SyncController
 import com.fabledsword.minstrel.library.data.LibraryRepository
 import com.fabledsword.minstrel.shared.UiState
+import com.fabledsword.minstrel.shared.asCacheFirstStateFlow
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
-private const val SHARE_STOP_TIMEOUT_MS = 5_000L
-
 @HiltViewModel
 class LibraryViewModel @Inject constructor(
     private val repository: LibraryRepository,
@@ -36,14 +31,7 @@ class LibraryViewModel @Inject constructor(
                 UiState.Success(LibraryData(artists, albums))
             }
         }
-            .catch { e ->
-                emit(UiState.Error(ErrorCopy.fromThrowable(e)))
-            }
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
-                initialValue = UiState.Loading,
-            )
+            .asCacheFirstStateFlow(viewModelScope)
 
     /**
      * Pull-to-refresh entry point. Triggers /api/library/sync via the

android/app/src/main/java/com/fabledsword/minstrel/likes/ui/LikedTab.kt

@@ -25,7 +25,6 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewModelScope
 import androidx.navigation.NavHostController
-import com.fabledsword.minstrel.api.ErrorCopy
 import com.fabledsword.minstrel.likes.data.LikesRepository
 import com.fabledsword.minstrel.library.widgets.AlbumCard
 import com.fabledsword.minstrel.library.widgets.ArtistCard
@@ -36,6 +35,7 @@ import com.fabledsword.minstrel.nav.AlbumDetail
 import com.fabledsword.minstrel.nav.ArtistDetail
 import com.fabledsword.minstrel.player.PlayerController
 import com.fabledsword.minstrel.shared.UiState
+import com.fabledsword.minstrel.shared.asCacheFirstStateFlow
 import com.fabledsword.minstrel.shared.widgets.TrackRow
 import com.fabledsword.minstrel.shared.widgets.EmptyState
 import com.fabledsword.minstrel.shared.widgets.HorizontalScrollRow
@@ -46,16 +46,11 @@ import com.fabledsword.minstrel.shared.widgets.TrackCoverThumb
 import com.fabledsword.minstrel.shared.widgets.trackactions.TrackActionsButton
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
-private const val SHARE_STOP_TIMEOUT_MS = 5_000L
-
 // ─── State ───────────────────────────────────────────────────────────
 
 data class LikedSections(
@@ -100,13 +95,7 @@ class LikedTabViewModel @Inject constructor(
     ) { artists, albums, tracks ->
         val sections = LikedSections(artists, albums, tracks)
         if (sections.isAllEmpty) UiState.Empty else UiState.Success(sections)
-    }
-        .catch { e -> emit(UiState.Error(ErrorCopy.fromThrowable(e))) }
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
-            initialValue = UiState.Loading,
-        )
+    }.asCacheFirstStateFlow(viewModelScope)
 
     /**
      * Build a queue from the currently-displayed liked tracks and start

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

@@ -21,13 +21,13 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewModelScope
 import androidx.navigation.NavHostController
-import com.fabledsword.minstrel.api.ErrorCopy
 import com.fabledsword.minstrel.events.EventsStream
 import com.fabledsword.minstrel.models.PlaylistRef
 import com.fabledsword.minstrel.nav.PlaylistDetail
 import com.fabledsword.minstrel.nav.Playlists
 import com.fabledsword.minstrel.playlists.data.PlaylistsRepository
 import com.fabledsword.minstrel.shared.UiState
+import com.fabledsword.minstrel.shared.asCacheFirstStateFlow
 import com.fabledsword.minstrel.playlists.widgets.PlaylistCard
 import com.fabledsword.minstrel.shared.widgets.EmptyState
 import com.fabledsword.minstrel.shared.widgets.LoadingCentered
@@ -35,17 +35,12 @@ import com.fabledsword.minstrel.shared.widgets.MinstrelTopAppBar
 import com.fabledsword.minstrel.shared.widgets.PullToRefreshScaffold
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
-private const val SHARE_STOP_TIMEOUT_MS = 5_000L
-
 // ─── State ───────────────────────────────────────────────────────────
 
 // ─── ViewModel ───────────────────────────────────────────────────────
@@ -81,14 +76,7 @@ class PlaylistsListViewModel @Inject constructor(
                     UiState.Success(list)
                 }
             }
-            .catch { e ->
-                emit(UiState.Error(ErrorCopy.fromThrowable(e)))
-            }
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
-                initialValue = UiState.Loading,
-            )
+            .asCacheFirstStateFlow(viewModelScope)
 }
 
 // ─── Screen ──────────────────────────────────────────────────────────

android/app/src/main/java/com/fabledsword/minstrel/shared/CacheFirstStateFlow.kt

@@ -0,0 +1,31 @@
+package com.fabledsword.minstrel.shared
+
+import com.fabledsword.minstrel.api.ErrorCopy
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.stateIn
+
+private const val SHARE_STOP_TIMEOUT_MS = 5_000L
+
+/**
+ * Terminal operator for the cache-first VM idiom: a Flow that maps
+ * cache emissions to `UiState.Success` / `UiState.Empty` becomes a
+ * subscriber-active StateFlow that starts in [UiState.Loading] and
+ * routes any upstream throwable through [ErrorCopy] into
+ * [UiState.Error].
+ *
+ * Replaces the catch + stateIn(viewModelScope, WhileSubscribed,
+ * Loading) tail that every cache-first ViewModel writes today.
+ */
+fun <T> Flow<UiState<T>>.asCacheFirstStateFlow(
+    scope: CoroutineScope,
+): StateFlow<UiState<T>> = this
+    .catch { e -> emit(UiState.Error(ErrorCopy.fromThrowable(e))) }
+    .stateIn(
+        scope = scope,
+        started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
+        initialValue = UiState.Loading,
+    )

android/app/src/main/java/com/fabledsword/minstrel/shared/widgets/trackactions/AddToPlaylistViewModel.kt

@@ -2,22 +2,17 @@ package com.fabledsword.minstrel.shared.widgets.trackactions
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
-import com.fabledsword.minstrel.api.ErrorCopy
 import com.fabledsword.minstrel.models.PlaylistRef
 import com.fabledsword.minstrel.playlists.data.PlaylistsRepository
 import com.fabledsword.minstrel.shared.UiState
+import com.fabledsword.minstrel.shared.asCacheFirstStateFlow
 import dagger.hilt.android.lifecycle.HiltViewModel
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onStart
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
-private const val SHARE_STOP_TIMEOUT_MS = 5_000L
-
 /**
  * Backs [AddToPlaylistSheet] with the caller's user-owned playlists.
  * System playlists (For You / Discover / etc.) are filtered out at
@@ -42,10 +37,5 @@ class AddToPlaylistViewModel @Inject constructor(
             }
             emit(UiState.Loading)
         }
-        .catch { e -> emit(UiState.Error(ErrorCopy.fromThrowable(e))) }
-        .stateIn(
-            scope = viewModelScope,
-            started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
-            initialValue = UiState.Loading,
-        )
+        .asCacheFirstStateFlow(viewModelScope)
 }