fix: handle background isolate shutdown on iOS

lib/services/bif_thumbnail_service.dart

@@ -1,4 +1,4 @@
-import 'dart:isolate';
+import '../utils/isolate_helper.dart';
 import 'dart:typed_data';
 
 import 'plex_client.dart';
@@ -76,7 +76,7 @@ class BifThumbnailService {
         appLogger.w('BIF file too large (${bytes.length} bytes), skipping');
         return;
       }
-      _entries = await Isolate.run(() => _parseBifBytes(bytes));
+      _entries = await tryIsolateRun(() => _parseBifBytes(bytes));
     } catch (e) {
       appLogger.w('BIF download/parse failed', error: e);
     }

lib/services/download_manager_service.dart

@@ -1085,6 +1085,7 @@ class DownloadManagerService {
     String? errorMessage,
     String? currentFile,
   }) {
+    if (_disposed) return;
     _progressController.add(
       DownloadProgress(
         globalKey: globalKey,
@@ -1118,6 +1119,7 @@ class DownloadManagerService {
 
   /// Emit progress update with artwork paths so DownloadProvider can sync
   void _emitProgressWithArtwork(String globalKey, {String? thumbPath}) {
+    if (_disposed) return;
     // Emit a progress update containing artwork path
     // The status is preserved as downloading since artwork is just one step
     _progressController.add(
@@ -1263,6 +1265,7 @@ class DownloadManagerService {
 
   /// Emit deletion progress update
   void _emitDeletionProgress(DeletionProgress progress) {
+    if (_disposed) return;
     _deletionProgressController.add(progress);
   }
 

lib/services/plex_api_cache.dart

@@ -1,5 +1,5 @@
 import 'dart:convert';
-import 'dart:isolate';
+import '../utils/isolate_helper.dart';
 
 import 'package:drift/drift.dart';
 
@@ -42,7 +42,7 @@ class PlexApiCache {
     final result = await (_db.select(_db.apiCache)..where((t) => t.cacheKey.equals(key))).getSingleOrNull();
 
     if (result != null) {
-      return await Isolate.run(() => jsonDecode(result.data) as Map<String, dynamic>);
+      return await tryIsolateRun(() => jsonDecode(result.data) as Map<String, dynamic>);
     }
     return null;
   }
@@ -50,7 +50,7 @@ class PlexApiCache {
   /// Cache a response for an endpoint
   Future<void> put(String serverId, String endpoint, Map<String, dynamic> data) async {
     final key = _buildKey(serverId, endpoint);
-    final encoded = await Isolate.run(() => jsonEncode(data));
+    final encoded = await tryIsolateRun(() => jsonEncode(data));
     await _db
         .into(_db.apiCache)
         .insertOnConflictUpdate(ApiCacheCompanion(cacheKey: Value(key), data: Value(encoded), cachedAt: Value(DateTime.now())));
@@ -145,7 +145,7 @@ class PlexApiCache {
 
     if (entries.isEmpty) return {};
 
-    return await Isolate.run(() {
+    return await tryIsolateRun(() {
       final result = <String, PlexMetadata>{};
       for (final (serverId, ratingKey, rawData) in entries) {
         try {

lib/services/plex_client.dart

@@ -1,6 +1,6 @@
 import 'dart:async';
 import 'dart:convert';
-import 'dart:isolate';
+import '../utils/isolate_helper.dart';
 import 'dart:math';
 import 'package:flutter/foundation.dart';
 
@@ -112,7 +112,7 @@ class ConnectionTestResult {
   ConnectionTestResult({required this.success, required this.latencyMs, this.error});
 }
 
-// Top-level function required by compute()
+// Top-level function required by tryIsolateRun()
 String _decodeUtf8(List<int> bytes) {
   return utf8.decode(bytes, allowMalformed: true);
 }
@@ -158,7 +158,7 @@ class PlexClient {
     ResponseBody responseBody,
   ) {
     if (responseBytes.length > 50 * 1024) {
-      return compute(_decodeUtf8, responseBytes);
+      return tryIsolateRun(() => _decodeUtf8(responseBytes));
     }
     return utf8.decode(responseBytes, allowMalformed: true);
   }
@@ -993,7 +993,7 @@ class PlexClient {
     final response = await _dio.get('/library/onDeck');
     final sid = serverId;
     final sname = serverName;
-    return await Isolate.run(() => _processOnDeckResponse(response.data as Map<String, dynamic>, sid, sname));
+    return await tryIsolateRun(() => _processOnDeckResponse(response.data as Map<String, dynamic>, sid, sname));
   }
 
   /// Get children of a metadata item (e.g., seasons for a show, episodes for a season)
@@ -1481,7 +1481,7 @@ class PlexClient {
       );
       final sid = serverId;
       final sname = serverName;
-      return await Isolate.run(() => _processHubResponse(response.data as Map<String, dynamic>, sid, sname));
+      return await tryIsolateRun(() => _processHubResponse(response.data as Map<String, dynamic>, sid, sname));
     } catch (e) {
       appLogger.e('Failed to get library hubs: $e');
     }
@@ -1496,7 +1496,7 @@ class PlexClient {
       final response = await _dio.get('/hubs', queryParameters: {'count': limit, 'includeGuids': 1});
       final sid = serverId;
       final sname = serverName;
-      return await Isolate.run(() => _processHubResponse(response.data as Map<String, dynamic>, sid, sname));
+      return await tryIsolateRun(() => _processHubResponse(response.data as Map<String, dynamic>, sid, sname));
     } catch (e) {
       appLogger.e('Failed to get global hubs: $e');
     }

lib/utils/isolate_helper.dart

@@ -0,0 +1,14 @@
+import 'dart:isolate';
+
+/// Runs [computation] in a background isolate via [Isolate.run].
+///
+/// Falls back to synchronous execution when the isolate infrastructure is
+/// unavailable (e.g. iOS killed background isolates while the app was
+/// suspended).
+Future<R> tryIsolateRun<R>(R Function() computation) async {
+  try {
+    return await Isolate.run(computation);
+  } on StateError {
+    return computation();
+  }
+}