refactor: shared coalescer, profile-scoped prefs key, and form-error helper

lib/services/storage_service.dart

@@ -96,12 +96,12 @@ class StorageService extends BaseSharedPreferencesService {
   /// full profile id is the scope.
   String? activeUserScope() => _activeUserScope();
 
-  String userScopeForProfileId(String profileId) => parsePlexHomeProfileId(profileId)?.homeUserUuid ?? profileId;
+  String userScopeForProfileId(String profileId) => profileUserScope(profileId);
 
   String? _activeUserScope() {
     final id = getActiveProfileId();
     if (id == null) return null;
-    return parsePlexHomeProfileId(id)?.homeUserUuid ?? id;
+    return profileUserScope(id);
   }
 
   /// Returns `'user_{scope}_'` for the active profile, or `''` if no

lib/services/trackers/future_coalescer.dart

@@ -12,4 +12,30 @@ class FutureCoalescer<T> {
     _inFlight = future;
     return future;
   }
+
+  /// Detach the in-flight future (it keeps running, but the next [run]
+  /// starts fresh instead of joining it). The identical-guard above keeps
+  /// the detached future's completion from clearing a newer slot.
+  void reset() {
+    _inFlight = null;
+  }
+}
+
+/// Keyed [FutureCoalescer]: one in-flight future per key. Used for the
+/// static per-identity re-auth/refresh maps (Trakt refresh-by-token, Seerr
+/// re-auth-by-instance) so concurrent 401s trigger one login each.
+class KeyedFutureCoalescer<K, T> {
+  final Map<K, Future<T>> _inFlight = {};
+
+  Future<T> run(K key, Future<T> Function() create) {
+    final existing = _inFlight[key];
+    if (existing != null) return existing;
+
+    late final Future<T> future;
+    future = create().whenComplete(() {
+      if (identical(_inFlight[key], future)) _inFlight.remove(key);
+    });
+    _inFlight[key] = future;
+    return future;
+  }
 }

lib/services/trackers/tracker_account_store.dart

@@ -1,3 +1,4 @@
+import '../../profiles/profile.dart';
 import '../base_shared_preferences_service.dart';
 import 'tracker_constants.dart';
 import 'tracker_session.dart';
@@ -25,7 +26,7 @@ class TrackerAccountStore {
 
   TrackerAccountStore._(this.service, this._baseKey);
 
-  String _scopedKey(String userUuid) => userUuid.isEmpty ? _baseKey : 'user_${userUuid}_$_baseKey';
+  String _scopedKey(String userUuid) => profileScopedPrefsKey(userUuid, _baseKey);
 
   Future<TrackerSession?> load(String userUuid) async {
     final prefs = await BaseSharedPreferencesService.sharedCache();