Offline resilience: persist playlist cache for cold-start recovery

Web player:
- Cache playlist JSON to localStorage on every update
- Restore and start playing immediately on boot before connecting
- Clear cache on unpair/reset

Android app:
- Cache playlist JSON to EncryptedSharedPreferences on every update
- Restore cached playlist on cold-start, play from disk-cached content
- Update cache on content deletion, clear on unpair

Server (device socket):
- Fingerprint reconnect: issue fresh token instead of rejecting
- Send device:paired on fingerprint recovery for claimed devices
- Add status logging and dashboard notification on fingerprint reconnect

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

android/app/src/main/java/com/remotedisplay/player/MainActivity.kt

@@ -147,7 +147,25 @@ class MainActivity : AppCompatActivity() {
             onVideoComplete = { playlistController.onVideoComplete() }
         )
 
+        // Restore cached playlist for offline cold-start (play immediately from disk cache)
+        val cachedJson = config.cachedPlaylist
+        if (cachedJson.isNotEmpty()) {
+            try {
+                val cached = JSONObject(cachedJson)
+                val assignments = cached.getJSONArray("assignments")
+                if (assignments.length() > 0) {
+                    Log.i("MainActivity", "Restoring cached playlist: ${assignments.length()} items")
+                    playlistController.updatePlaylist(assignments)
+                    playlistController.startIfNeeded()
+                }
+            } catch (e: Exception) {
+                Log.w("MainActivity", "Failed to restore cached playlist: ${e.message}")
+            }
+        }
+
+        if (!playlistController.isPlaying) {
             showStatus("Connecting to server...")
+        }
 
         // Start and bind to WebSocket service
         try {
@@ -184,6 +202,9 @@ class MainActivity : AppCompatActivity() {
 
             val assignments = data.getJSONArray("assignments")
 
+            // Cache playlist JSON for offline cold-start
+            config.cachedPlaylist = data.toString()
+
             // Check for multi-zone layout
             val layoutObj = if (data.isNull("layout")) null else data.optJSONObject("layout")
             val layoutZones = layoutObj?.optJSONArray("zones")
@@ -272,6 +293,20 @@ class MainActivity : AppCompatActivity() {
         wsService?.onContentDelete = { contentId ->
             contentCache.deleteContent(contentId)
             playlistController.removeContent(contentId)
+            // Update cached playlist to reflect deletion
+            try {
+                val cached = JSONObject(config.cachedPlaylist)
+                val arr = cached.optJSONArray("assignments")
+                if (arr != null) {
+                    val filtered = org.json.JSONArray()
+                    for (i in 0 until arr.length()) {
+                        val item = arr.getJSONObject(i)
+                        if (item.optString("content_id") != contentId) filtered.put(item)
+                    }
+                    cached.put("assignments", filtered)
+                    config.cachedPlaylist = cached.toString()
+                }
+            } catch (_: Exception) {}
         }
 
         wsService?.onScreenshotRequest = {
@@ -360,6 +395,7 @@ class MainActivity : AppCompatActivity() {
 
         wsService?.onUnpaired = {
             Log.w("MainActivity", "Device removed from server, going to provisioning")
+            config.clearPlaylistCache()
             handler.post {
                 startActivity(Intent(this, ProvisioningActivity::class.java).apply {
                     addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK or Intent.FLAG_ACTIVITY_NEW_TASK)

android/app/src/main/java/com/remotedisplay/player/data/ServerConfig.kt

@@ -62,4 +62,13 @@ class ServerConfig(context: Context) {
     fun clear() {
         prefs.edit().clear().apply()
     }
+
+    // Playlist cache for offline cold-start
+    var cachedPlaylist: String
+        get() = prefs.getString("cached_playlist", "") ?: ""
+        set(value) = prefs.edit().putString("cached_playlist", value).apply()
+
+    fun clearPlaylistCache() {
+        prefs.edit().remove("cached_playlist").apply()
+    }
 }

server/player/index.html

@@ -88,6 +88,13 @@
       try { return JSON.parse(localStorage.getItem(STORAGE_KEY) || '{}'); } catch { return {}; }
     }
     function saveConfig(cfg) { localStorage.setItem(STORAGE_KEY, JSON.stringify(cfg)); }
+    const PLAYLIST_CACHE_KEY = 'rd_playlist_cache';
+    function savePlaylistCache(items) {
+      try { localStorage.setItem(PLAYLIST_CACHE_KEY, JSON.stringify(items)); } catch {}
+    }
+    function loadPlaylistCache() {
+      try { return JSON.parse(localStorage.getItem(PLAYLIST_CACHE_KEY) || '[]'); } catch { return []; }
+    }
 
     // ==================== State ====================
     let socket = null;
@@ -162,6 +169,17 @@
     }
 
     if (config.serverUrl && config.deviceId && config.paired) {
+      // Restore cached playlist immediately so content plays even if offline
+      const cachedPlaylist = loadPlaylistCache();
+      if (cachedPlaylist.length > 0) {
+        console.log('Restored cached playlist:', cachedPlaylist.length, 'items');
+        playlist = cachedPlaylist;
+        currentIndex = 0;
+        isPlaying = true;
+        document.getElementById('setupScreen').style.display = 'none';
+        playCurrentItem();
+      }
+
       // Show tap-to-start overlay to unlock audio on auto-reconnect
       const tapOverlay = document.createElement('div');
       tapOverlay.style.cssText = 'position:fixed;inset:0;background:#111827;z-index:2000;display:flex;flex-direction:column;align-items:center;justify-content:center;cursor:pointer';
@@ -285,6 +303,7 @@
         delete config.deviceToken;
         config.paired = false;
         saveConfig(config);
+        savePlaylistCache([]);
         document.getElementById('setupScreen').style.display = 'flex';
         document.getElementById('urlForm').style.display = 'block';
         document.getElementById('pairingSection').style.display = 'none';
@@ -310,6 +329,7 @@
 
       socket.on('device:content-delete', (data) => {
         playlist = playlist.filter(p => p.content_id !== data.content_id);
+        savePlaylistCache(playlist);
         if (playlist.length === 0) showStatus('Waiting for content...');
       });
 
@@ -486,6 +506,7 @@
 
       console.log('Playlist changed, updating');
       playlist = newItems;
+      savePlaylistCache(playlist);
 
       if (playlist.length === 0) {
         showStatus('Waiting for content...');
@@ -939,6 +960,7 @@
         // Reset config and go back to setup
         if (confirm('Reset player and return to setup?')) {
           localStorage.removeItem(STORAGE_KEY);
+          localStorage.removeItem(PLAYLIST_CACHE_KEY);
           location.reload();
         }
       }

server/ws/deviceSocket.js

@@ -139,19 +139,24 @@ module.exports = function setupDeviceSocket(io) {
               // Someone reinstalled - link them back to existing device
               const oldDevice = db.prepare('SELECT * FROM devices WHERE id = ?').get(existing.device_id);
               if (oldDevice) {
-                // Validate token if the old device has one
-                if (oldDevice.device_token && !validateDeviceToken(existing.device_id, device_token)) {
-                  console.warn(`Fingerprint match but invalid token for device ${existing.device_id}`);
-                  // Generate a new token — the reinstalled app needs a fresh one via re-pairing
-                  socket.emit('device:unpaired', { reason: 'invalid_token' });
-                  return;
-                }
-                console.log(`Fingerprint match: linking to existing device ${existing.device_id}`);
+                // Fingerprint matched — this is a reinstalled app reconnecting to its old device.
+                // Issue a fresh token so the app can authenticate going forward.
+                const newToken = generateDeviceToken();
+                db.prepare('UPDATE devices SET device_token = ? WHERE id = ?').run(newToken, existing.device_id);
+                console.log(`Fingerprint match: linking reinstalled app to existing device ${existing.device_id} (new token issued)`);
                 authenticated = true;
-                socket.emit('device:registered', { device_id: existing.device_id, device_token: oldDevice.device_token, status: oldDevice.status });
+                db.prepare("UPDATE devices SET status = 'online', last_heartbeat = strftime('%s','now'), ip_address = ?, updated_at = strftime('%s','now') WHERE id = ?")
+                  .run(getClientIp(socket), existing.device_id);
+                socket.emit('device:registered', { device_id: existing.device_id, device_token: newToken, status: 'online' });
+                // If device was already claimed by a user, tell the player it's paired
+                if (oldDevice.user_id) {
+                  socket.emit('device:paired', { name: oldDevice.name || 'Display' });
+                }
                 currentDeviceId = existing.device_id;
                 heartbeat.registerConnection(existing.device_id, socket.id);
                 socket.join(existing.device_id);
+                logDeviceStatus(existing.device_id, 'online');
+                dashboardNs.emit('dashboard:device-status', { device_id: existing.device_id, status: 'online' });
                 // Send playlist
                 const access = checkDeviceAccess(existing.device_id);
                 if (!access.allowed) {