fix(android): reconcile playlist cache to prune stale system-playlist UUIDs

Tapping certain playlists showed 'That playlist no longer exists' because the server's BuildSystemPlaylists rotates system-playlist UUIDs every rebuild, and the LIST refresh only upserted -- stale UUIDs lingered in the cache, tapping them triggered a 404. Mirrors playlists_provider.dart: PlaylistsRepository.refreshList now deletes the user's cached rows not in the fresh owned set (catches both deleted user playlists AND old system UUIDs since system playlists are user-scoped) before upserting the fresh all, atomically via a new replaceList @Transaction on the DAO. Also deletes the cached row when refreshDetail 404s so a stale tap self-heals the list. Inject AuthController for the current user id.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/cache/db/dao/CachedPlaylistDao.kt

@@ -4,6 +4,7 @@ import androidx.room.Dao
 import androidx.room.Insert
 import androidx.room.OnConflictStrategy
 import androidx.room.Query
+import androidx.room.Transaction
 import com.fabledsword.minstrel.cache.db.entities.CachedPlaylistEntity
 import kotlinx.coroutines.flow.Flow
 
@@ -35,4 +36,35 @@ interface CachedPlaylistDao {
 
     @Query("DELETE FROM cached_playlists WHERE id IN (:ids)")
     suspend fun deleteByIds(ids: List<String>)
+
+    @Query("DELETE FROM cached_playlists WHERE userId = :userId")
+    suspend fun deleteAllOwned(userId: String)
+
+    @Query("DELETE FROM cached_playlists WHERE userId = :userId AND id NOT IN (:keepIds)")
+    suspend fun deleteOwnedNotIn(userId: String, keepIds: List<String>)
+
+    /**
+     * Atomically reconciles the cache against the fresh list response.
+     * Mirrors `flutter_client/lib/playlists/playlists_provider.dart:54` —
+     * `BuildSystemPlaylists` rotates system-playlist UUIDs every
+     * rebuild, so upsert alone leaves stale rows whose detail fetch
+     * 404s. Delete any of the user's rows not in [freshOwnedIds] (this
+     * catches both deleted owned playlists AND old system-playlist
+     * UUIDs, since system playlists are user-scoped and appear in
+     * [all] under their new id rather than in [freshOwnedIds]), then
+     * upsert the fresh set.
+     */
+    @Transaction
+    suspend fun replaceList(
+        userId: String,
+        freshOwnedIds: List<String>,
+        all: List<CachedPlaylistEntity>,
+    ) {
+        if (freshOwnedIds.isEmpty()) {
+            deleteAllOwned(userId)
+        } else {
+            deleteOwnedNotIn(userId, freshOwnedIds)
+        }
+        upsertAll(all)
+    }
 }

android/app/src/main/java/com/fabledsword/minstrel/playlists/data/PlaylistsRepository.kt

@@ -2,6 +2,9 @@ package com.fabledsword.minstrel.playlists.data
 
 import com.fabledsword.minstrel.api.endpoints.AppendTracksRequest
 import com.fabledsword.minstrel.api.endpoints.PlaylistsApi
+import com.fabledsword.minstrel.auth.AuthController
+import retrofit2.HttpException
+import java.net.HttpURLConnection
 import com.fabledsword.minstrel.cache.db.dao.CachedPlaylistDao
 import com.fabledsword.minstrel.cache.db.dao.CachedPlaylistTrackDao
 import com.fabledsword.minstrel.cache.db.entities.CachedPlaylistEntity
@@ -39,6 +42,7 @@ class PlaylistsRepository @Inject constructor(
     private val playlistDao: CachedPlaylistDao,
     private val playlistTrackDao: CachedPlaylistTrackDao,
     private val mutationQueue: MutationQueue,
+    private val authController: AuthController,
     retrofit: Retrofit,
 ) {
     private val api: PlaylistsApi = retrofit.create()
@@ -67,8 +71,21 @@ class PlaylistsRepository @Inject constructor(
      */
     suspend fun refreshList() {
         val wire = api.list(kind = "all")
-        val all = wire.owned + wire.public
-        playlistDao.upsertAll(all.map { it.toEntity() })
+        val all = (wire.owned + wire.public).map { it.toEntity() }
+        val userId = authController.currentUser.value?.id
+        if (userId != null) {
+            // Reconcile: BuildSystemPlaylists rotates system-playlist
+            // UUIDs every rebuild, so upsert alone leaves stale rows
+            // whose detail fetch 404s ("That playlist no longer
+            // exists"). Mirrors playlists_provider.dart's deleteWhere.
+            playlistDao.replaceList(
+                userId = userId,
+                freshOwnedIds = wire.owned.map { it.id },
+                all = all,
+            )
+        } else {
+            playlistDao.upsertAll(all)
+        }
     }
 
     /**
@@ -79,7 +96,17 @@ class PlaylistsRepository @Inject constructor(
      * track-membership IDs, not the display fields.
      */
     suspend fun refreshDetail(id: String): PlaylistDetailRef {
-        val wire = api.get(id)
+        val wire = try {
+            api.get(id)
+        } catch (e: HttpException) {
+            // Server says this playlist is gone — drop the stale cache
+            // row so the list stops showing it. Mirrors
+            // playlists_provider.dart's deleteWhere on detail failure.
+            if (e.code() == HttpURLConnection.HTTP_NOT_FOUND) {
+                playlistDao.deleteByIds(listOf(id))
+            }
+            throw e
+        }
         playlistDao.upsertAll(listOf(wire.toPlaylistEntity()))
         playlistTrackDao.deleteByPlaylist(id)
         playlistTrackDao.upsertAll(