feat: fetch tracks on-demand, logout button

BUGS.md

@@ -8,6 +8,9 @@
 
 - the server should implement some rate limiting / deadman switch / to avoid spamming Spotify API with broken-app API calls
 
+- pairing fails:
+	- (tag data from mp3 files is there)
+	- are we missing tracks? (or title/artist on the tracks?)
 
 ## Nice-to
 
@@ -22,3 +25,34 @@
 
 
 - toast: "no tracks loaded for this playlist yet.  [...]"
+
+## Spotify API check
+
+after fetching about 90 playlists, I start to see 429 rate limiting.
+
+ALSO, now, I seem to get this very soon with 429:
+(even after logging in again)
+"""
+
+84.115.228.119 - - [14/May/2026 00:46:04] "GET /playlists HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:05] "GET /playlists HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:07] "GET /playlists HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:09] "GET /playlists/4f4P6ULiHn0oEedTHal2AU HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:10] "GET /playlists/4f4P6ULiHn0oEedTHal2AU HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:12] "GET /playlists HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:12] "GET /playlists/4f4P6ULiHn0oEedTHal2AU HTTP/1.1" 429 -
+
+
+84.115.228.119 - - [14/May/2026 00:46:17] "GET /playlists/4f4P6ULiHn0oEedTHal2AU HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:22] "GET /playlists HTTP/1.1" 429 -
+84.115.228.119 - - [14/May/2026 00:46:26] "GET /playlists/4f4P6ULiHn0oEedTHal2AU HTTP/1.1" 429 -
+
+"""
+
+---
+
+"""
+can we please *avoid* fetching playlist details upon first-run? i.e. only fetch the playlists but not their contents.
+*only* fetch playlist details upon clicking a playlist.
+"""
+

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,

app/src/main/java/at/lockstep/player/ui/LockstepAppNavHost.kt

@@ -80,6 +80,7 @@ fun LockstepAppNavHost(
         }
         composable(Routes.Settings) {
             SettingsScreen(
+                viewModel = viewModel,
                 onBack = { navController.popBackStack() },
             )
         }

app/src/main/java/at/lockstep/player/ui/library/LibraryScreen.kt

@@ -83,6 +83,11 @@ fun LibraryScreen(
                             .fillMaxWidth()
                             .clickable {
                                 scope.launch {
+                                    val err = viewModel.syncPlaylistDetailForLibraryOpen(playlist.id)
+                                    if (err != null) {
+                                        Toast.makeText(context, err, Toast.LENGTH_LONG).show()
+                                        return@launch
+                                    }
                                     val hasPaired =
                                         viewModel.hasPairedTracks(playlist.id)
                                     onPlaylistSelected(playlist, hasPaired)

app/src/main/java/at/lockstep/player/ui/settings/SettingsScreen.kt

@@ -6,6 +6,8 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.Button
+import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -17,11 +19,13 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.unit.dp
+import at.lockstep.player.LockstepViewModel
 import at.lockstep.player.R
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun SettingsScreen(
+    viewModel: LockstepViewModel,
     onBack: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
@@ -51,6 +55,21 @@ fun SettingsScreen(
                 text = context.getString(R.string.settings_stub_body),
                 style = MaterialTheme.typography.bodyLarge,
             )
+            Text(
+                text = context.getString(R.string.settings_logout_spotify_help),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+            Button(
+                onClick = { viewModel.logoutSpotifyAndRestartOnboarding() },
+                colors =
+                    ButtonDefaults.buttonColors(
+                        containerColor = MaterialTheme.colorScheme.errorContainer,
+                        contentColor = MaterialTheme.colorScheme.onErrorContainer,
+                    ),
+            ) {
+                Text(text = context.getString(R.string.settings_logout_spotify))
+            }
         }
     }
 }

app/src/main/res/values/strings.xml

@@ -26,6 +26,8 @@
 
     <string name="settings_title">Settings</string>
     <string name="settings_stub_body">More controls will land here in a later milestone.</string>
+    <string name="settings_logout_spotify">Sign out of Spotify</string>
+    <string name="settings_logout_spotify_help">Clears your stored access token and returns to the welcome steps so you can log in again. Use this if the app gets HTTP 401 from the server.</string>
 
     <string name="pairing_title">Pair local MP3s</string>
     <string name="pairing_choose_folder">Choose folder of MP3s</string>