look ahead

lib/providers/sync_provider.dart

@@ -51,6 +51,8 @@ class SyncController extends ChangeNotifier {
   bool _queuedFullSync = false;
   Timer? _pushDebounce;
   Timer? _progressHold;
+  Timer? _uiNotifyThrottle;
+  var _uiNotifyQueued = false;
   String? _lastError;
   DateTime? _lastSyncedAt;
   String _lastSyncSummary = '';
@@ -64,6 +66,7 @@ class SyncController extends ChangeNotifier {
   double _syncProgress = 0;
   bool _showProgressRing = false;
   bool _progressSuccess = false;
+  int _lastNotifiedProgressPct = -1;
 
   bool get isSyncing => _syncing;
   String? get lastError => _lastError;
@@ -86,6 +89,25 @@ class SyncController extends ChangeNotifier {
   /// Ring turns green when this is true (sync finished successfully).
   bool get progressSuccess => _progressSuccess;
 
+  void _notifyUiNow() {
+    _uiNotifyThrottle?.cancel();
+    _uiNotifyQueued = false;
+    _lastNotifiedProgressPct = (_syncProgress * 100).round();
+    notifyListeners();
+  }
+
+  /// Coalesce high-frequency progress/status into ~10 Hz UI updates.
+  void _notifyUiThrottled() {
+    if (_uiNotifyQueued) return;
+    _uiNotifyQueued = true;
+    _uiNotifyThrottle?.cancel();
+    _uiNotifyThrottle = Timer(const Duration(milliseconds: 100), () {
+      _uiNotifyQueued = false;
+      _lastNotifiedProgressPct = (_syncProgress * 100).round();
+      notifyListeners();
+    });
+  }
+
   void _announce(String message, {bool isProgress = false, bool isError = false}) {
     _feedbackEpoch++;
     _feedback = SyncFeedback(
@@ -94,24 +116,38 @@ class SyncController extends ChangeNotifier {
       isProgress: isProgress,
       isError: isError,
     );
-    notifyListeners();
+    _notifyUiNow();
   }
 
   void _setProgress(double value, {bool success = false}) {
-    _syncProgress = value.clamp(0.0, 1.0);
+    final next = value.clamp(0.0, 1.0);
+    final pct = (next * 100).round();
+    _syncProgress = next;
     _showProgressRing = true;
     _progressSuccess = success;
-    notifyListeners();
+    // Skip tiny progress moves — avatar only shows whole percents.
+    if (!success &&
+        pct == _lastNotifiedProgressPct &&
+        _showProgressRing) {
+      return;
+    }
+    if (success) {
+      _notifyUiNow();
+    } else {
+      _notifyUiThrottled();
+    }
   }
 
   void _setStatus(String message) {
     if (_statusDetail == message) return;
     _statusDetail = message;
-    notifyListeners();
+    _notifyUiThrottled();
   }
 
   void _finishProgress({required bool success}) {
     _progressHold?.cancel();
+    _uiNotifyThrottle?.cancel();
+    _uiNotifyQueued = false;
     _statusDetail = '';
     if (success) {
       _setProgress(1, success: true);
@@ -119,13 +155,15 @@ class SyncController extends ChangeNotifier {
         _showProgressRing = false;
         _progressSuccess = false;
         _syncProgress = 0;
-        notifyListeners();
+        _lastNotifiedProgressPct = -1;
+        _notifyUiNow();
       });
     } else {
       _showProgressRing = false;
       _progressSuccess = false;
       _syncProgress = 0;
-      notifyListeners();
+      _lastNotifiedProgressPct = -1;
+      _notifyUiNow();
     }
   }
 
@@ -138,12 +176,15 @@ class SyncController extends ChangeNotifier {
     if (!loggedIn) {
       _pushDebounce?.cancel();
       _progressHold?.cancel();
+      _uiNotifyThrottle?.cancel();
+      _uiNotifyQueued = false;
       _lastError = null;
       _statusDetail = '';
       _showProgressRing = false;
       _progressSuccess = false;
       _syncProgress = 0;
-      notifyListeners();
+      _lastNotifiedProgressPct = -1;
+      _notifyUiNow();
     }
   }
 
@@ -191,8 +232,11 @@ class SyncController extends ChangeNotifier {
       _setProgress(0.5);
       _setStatus('Merging…');
       final mergedMeta = mergeTxMetaStores(_meta.exportStore(), remoteMeta);
-      await _meta.replaceStore(mergedMeta);
-      await _bank.applySyncedTransactions(remoteTxs);
+      // Apply without notifying — one rebuild after both stores are ready.
+      await _meta.replaceStore(mergedMeta, notify: false);
+      await _bank.applySyncedTransactions(remoteTxs, notify: false);
+      _meta.notifyListeners();
+      _bank.notifyListeners();
       _setProgress(0.55);
       _setStatus('Pushing…');
       final metaSummary = await service.push(
@@ -283,6 +327,7 @@ class SyncController extends ChangeNotifier {
   void dispose() {
     _pushDebounce?.cancel();
     _progressHold?.cancel();
+    _uiNotifyThrottle?.cancel();
     _auth.removeListener(_onAuthChanged);
     _meta.onPersisted = null;
     super.dispose();