fix(ui): stop the merge-helper tick from re-ticking unticked candidates

src/ClaudeDo.Ui/ViewModels/Modals/MergeHelperSelectionModalViewModel.cs

@@ -41,6 +41,10 @@ public sealed partial class MergeHelperSelectionModalViewModel : ViewModelBase
     // Parent id -> its child rows, built after load; drives the tick-parent-ticks-children cascade.
     private Dictionary<string, List<MergeHelperTaskRowViewModel>> _childrenByParentId = new();
 
+    // Set while ReconcileTickAsync restores remembered ticks, so replaying a parent's state
+    // doesn't cascade over its children's own remembered state.
+    private bool _suppressCascade;
+
     public ObservableCollection<MergeHelperTaskRowViewModel> Tasks { get; } = new();
 
     [ObservableProperty] private string _scopeLabel = "";
@@ -70,16 +74,31 @@ public sealed partial class MergeHelperSelectionModalViewModel : ViewModelBase
         ScopeLabel = Loc.T("modals.mergeHelper.scopeList", listName);
     }
 
-    // LoadAsync rebuilds every row from scratch, which would wipe the user's ticks out from
-    // under them on every tick — capture and restore selection by id around the reload.
+    // LoadAsync rebuilds every row from scratch and re-applies IsTickedByDefault, which would wipe
+    // the user's ticks out from under them on every tick — in BOTH directions. Remembering only
+    // the ticked ids would silently re-tick a row the user deliberately unticked (Idle/Queued/
+    // WaitingForReview/Failed all default to ticked), so carry the full state of every row that
+    // already existed across the reload; only genuinely new rows get the default.
     internal async Task ReconcileTickAsync()
     {
         if (string.IsNullOrEmpty(_listId)) return;
-        var selected = Tasks.Where(t => t.IsSelected).Select(t => t.Id).ToHashSet();
+        var previous = Tasks.ToDictionary(t => t.Id, t => t.IsSelected);
         await LoadAsync();
-        foreach (var t in Tasks)
-            if (selected.Contains(t.Id))
-                t.IsSelected = true;
+
+        // Restore without the parent→children cascade: it would overwrite a child's own remembered
+        // state with its parent's, undoing exactly the per-child choice being restored.
+        _suppressCascade = true;
+        try
+        {
+            foreach (var t in Tasks)
+                if (previous.TryGetValue(t.Id, out var wasSelected))
+                    t.IsSelected = wasSelected;
+        }
+        finally
+        {
+            _suppressCascade = false;
+        }
+
         OnPropertyChanged(nameof(CanConfirm));
     }
 
@@ -162,7 +181,8 @@ public sealed partial class MergeHelperSelectionModalViewModel : ViewModelBase
         // Ticking/unticking a parent cascades to its children; a child can still be
         // deselected on its own afterwards without affecting the parent's checkbox —
         // ClaudeDo has no indeterminate/tri-state parent checkbox.
-        if (sender is MergeHelperTaskRowViewModel row
+        if (!_suppressCascade
+            && sender is MergeHelperTaskRowViewModel row
             && _childrenByParentId.TryGetValue(row.Id, out var children))
         {
             foreach (var child in children) child.IsSelected = row.IsSelected;