feat: fetch tracks on-demand, logout button

app/src/main/java/at/lockstep/player/LockstepViewModel.kt

@@ -128,7 +128,7 @@ class LockstepViewModel(
         app.setSpotifyAccessTokenForApi(token)
         return withContext(Dispatchers.IO) {
             try {
-                app.playlistRepository.syncInitial()
+                app.playlistRepository.syncDelta(false)
                 null
             } catch (e: LockstepApiException) {
                 e.message ?: "Sync failed"
@@ -138,6 +138,27 @@ class LockstepViewModel(
         }
     }
 
+    suspend fun syncPlaylistDetailForLibraryOpen(playlistId: String): String? {
+        val token = spotifyAccessToken.value
+        if (token.isNullOrBlank()) {
+            return "Not signed in"
+        }
+        app.setSpotifyAccessTokenForApi(token)
+        return withContext(Dispatchers.IO) {
+            if (app.playlistRepository.getTracks(playlistId).isNotEmpty()) {
+                return@withContext null
+            }
+            try {
+                app.playlistRepository.syncPlaylistDetail(playlistId)
+                null
+            } catch (e: LockstepApiException) {
+                e.message ?: "Load failed"
+            } catch (e: IOException) {
+                e.message ?: "Load failed"
+            }
+        }
+    }
+
     fun completeOnboarding() {
         viewModelScope.launch {
             prefs.setOnboardingComplete(true)
@@ -150,6 +171,14 @@ class LockstepViewModel(
         }
     }
 
+    /** Clears the Spotify token and shows the first-run flow again so you can sign in with a fresh token. */
+    fun logoutSpotifyAndRestartOnboarding() {
+        viewModelScope.launch {
+            prefs.setSpotifyAccessToken(null)
+            prefs.setOnboardingComplete(false)
+        }
+    }
+
     private suspend fun upsertPairing(
         playlistId: String,
         trackId: String,