feat(ui): add reconcile tick to self-heal lost worker broadcasts

TasksIslandViewModel now runs a periodic tick that diffs the flat Items
collection against SQLite and patches properties in place (capped at 500
rows, sharing the Phase 1 delta sequence guard so it never overtakes a
fresher broadcast). Never rebuilds rows or triggers Regroup/LoadForList, so
it stays decoupled from the parallel Phase 2b virtualization work. The same
cadence now refreshes the long-lived Worktrees Overview, Log Visualizer, and
Merge Helper selection overlays; short-lived modals are untouched.

src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs

@@ -1,5 +1,6 @@
 using System.Collections.ObjectModel;
 using System.Globalization;
+using Avalonia.Threading;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using ClaudeDo.Data;
@@ -29,6 +30,8 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
     // one task can be in flight at once. Only the newest may write to the row.
     private readonly Dictionary<string, long> _deltaSeq = new();
     private long _deltaCounter;
+    // Phase 3 reconcile tick — see the block at the end of this class.
+    private readonly System.Timers.Timer _reconcileTimer = new(4_000);
 
     public event EventHandler? SelectionChanged;
     public event EventHandler? FocusAddTaskRequested;
@@ -127,11 +130,15 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         }
         _langChangedHandler = (_, _) => RefreshLocalizedText();
         Loc.LanguageChanged += _langChangedHandler;
+        _reconcileTimer.Elapsed += (_, _) => Dispatcher.UIThread.Post(() => _ = ReconcileTickAsync());
+        _reconcileTimer.Start();
     }
 
     public void Dispose()
     {
         Loc.LanguageChanged -= _langChangedHandler;
+        _reconcileTimer.Stop();
+        _reconcileTimer.Dispose();
     }
 
     private void RefreshLocalizedText()
@@ -1225,4 +1232,81 @@ public sealed partial class TasksIslandViewModel : ViewModelBase, IDisposable
         foreach (var i in Items) i.IsSelected = ReferenceEquals(i, value);
         SelectionChanged?.Invoke(this, EventArgs.Empty);
     }
+
+    // ── Phase 3: reconcile tick ──────────────────────────────────────────────
+    // Self-healing safety net for a lost broadcast: every few seconds, diff the flat `Items`
+    // master collection against SQLite and patch properties in place. Never rebuilds a row,
+    // never calls Regroup() (Phase 2b owns OverdueItems/OpenItems/CompletedItems/Regroup and is
+    // rewriting them in parallel), and never falls back to LoadForList — the delta path already
+    // owns that escalation.
+
+    // Above this many rows, only the first N (in Items order) are reconciled per tick, so the
+    // query cost stays bounded instead of growing with an ever-larger list.
+    internal const int ReconcileRowCap = 500;
+
+    // Set by the shell from the main window's WindowState; the tick no-ops while minimized.
+    public bool IsWindowVisible { get; set; } = true;
+
+    // Test seam: awaited right after the reconcile query returns and before its results are
+    // applied, so a test can land a fresher, higher-sequence update in that gap and exercise the
+    // stale-sequence guard deterministically. Always null outside tests.
+    internal Func<Task>? ReconcileTickTestBarrier { get; set; }
+
+    // Awaitable so tests can drive it deterministically (mirrors RefreshTaskFromWorkerAsync).
+    internal async Task ReconcileTickAsync(CancellationToken ct = default)
+    {
+        var list = _currentList;
+        if (!IsWindowVisible || list is null) return;
+
+        // Mirrors the full-reload guard in RefreshTaskFromWorkerAsync: matching virtual:queued /
+        // virtual:running depends on a Planning parent's children, not a single entity.
+        if (list.Kind == ListKind.Virtual &&
+            (list.Id == "virtual:queued" || list.Id == "virtual:running"))
+            return;
+
+        var ids = Items.Select(r => r.Id).Take(ReconcileRowCap).ToList();
+        if (ids.Count == 0) return;
+
+        // Same monotonic per-task sequence as the Phase 1 delta path, so whichever of the two
+        // started most recently for a given task id wins, regardless of completion order.
+        var seqByTaskId = new Dictionary<string, long>(ids.Count);
+        foreach (var id in ids)
+        {
+            var seq = ++_deltaCounter;
+            seqByTaskId[id] = seq;
+            _deltaSeq[id] = seq;
+        }
+
+        List<TaskEntity> entities;
+        try
+        {
+            var idSet = ids.ToHashSet();
+            await using var db = await _dbFactory.CreateDbContextAsync(ct);
+            entities = await db.Tasks
+                .Include(t => t.List)
+                .Include(t => t.Worktree)
+                .Where(t => idSet.Contains(t.Id))
+                .ToListAsync(ct);
+        }
+        catch (OperationCanceledException) { return; }
+        catch (Exception ex)
+        {
+            System.Diagnostics.Debug.WriteLine($"TasksIsland: reconcile tick failed ({ex.Message})");
+            return;
+        }
+
+        if (ReconcileTickTestBarrier is { } barrier) await barrier();
+
+        var byId = entities.ToDictionary(e => e.Id);
+        foreach (var id in ids)
+        {
+            // Superseded by a fresher delta refresh or a later tick that landed while this one
+            // was reading — its result is stale, discard it.
+            if (!_deltaSeq.TryGetValue(id, out var current) || current != seqByTaskId[id]) continue;
+            if (!byId.TryGetValue(id, out var entity)) continue; // deleted; the delta path removes rows, not the tick
+
+            var row = Items.FirstOrDefault(r => r.Id == id);
+            row?.UpdateFromEntity(entity);
+        }
+    }
 }

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

@@ -41,8 +41,16 @@ public sealed partial class LogVisualizerViewModel : ViewModelBase
         _worker = worker;
         _copyToClipboard = copyToClipboard;
         Rows.CollectionChanged += (_, _) => CopyLastCommand.NotifyCanExecuteChanged();
+        // Phase 3 reconcile tick: this overlay is long-lived (stays open while the user reads
+        // through the log), so refresh it on the same cadence as TasksIslandViewModel's tick
+        // instead of leaving it frozen at the moment it was opened.
+        _reconcileTimer.Elapsed += (_, _) =>
+            Avalonia.Threading.Dispatcher.UIThread.Post(() => _ = RefreshAsync());
+        _reconcileTimer.Start();
     }
 
+    private readonly System.Timers.Timer _reconcileTimer = new(4_000);
+
     [RelayCommand]
     public async Task RefreshAsync()
     {
@@ -65,7 +73,13 @@ public sealed partial class LogVisualizerViewModel : ViewModelBase
             : Loc.T("modals.logVisualizer.count", Rows.Count);
     }
 
-    [RelayCommand] private void Close() => CloseAction?.Invoke();
+    [RelayCommand]
+    private void Close()
+    {
+        _reconcileTimer.Stop();
+        _reconcileTimer.Dispose();
+        CloseAction?.Invoke();
+    }
 
     private bool CanCopyLast() => Rows.Count > 0;
 

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

@@ -51,8 +51,18 @@ public sealed partial class MergeHelperSelectionModalViewModel : ViewModelBase
     public TaskCompletionSource<IReadOnlyList<string>?> Result { get; } = new();
     public Action? CloseAction { get; set; }
 
+    private readonly System.Timers.Timer _reconcileTimer = new(4_000);
+
     public MergeHelperSelectionModalViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory)
-        => _dbFactory = dbFactory;
+    {
+        _dbFactory = dbFactory;
+        // Phase 3 reconcile tick: this overlay is long-lived (stays open while the user ticks
+        // through candidates), so refresh it on the same cadence as TasksIslandViewModel's tick
+        // instead of leaving it frozen at the moment it was opened.
+        _reconcileTimer.Elapsed += (_, _) =>
+            Avalonia.Threading.Dispatcher.UIThread.Post(() => _ = ReconcileTickAsync());
+        _reconcileTimer.Start();
+    }
 
     public void Configure(string listId, string listName)
     {
@@ -60,6 +70,19 @@ 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.
+    internal async Task ReconcileTickAsync()
+    {
+        if (string.IsNullOrEmpty(_listId)) return;
+        var selected = Tasks.Where(t => t.IsSelected).Select(t => t.Id).ToHashSet();
+        await LoadAsync();
+        foreach (var t in Tasks)
+            if (selected.Contains(t.Id))
+                t.IsSelected = true;
+        OnPropertyChanged(nameof(CanConfirm));
+    }
+
     public async Task LoadAsync(CancellationToken ct = default)
     {
         foreach (var row in Tasks) row.PropertyChanged -= OnRowChanged;
@@ -163,6 +186,7 @@ public sealed partial class MergeHelperSelectionModalViewModel : ViewModelBase
     [RelayCommand]
     private void Confirm()
     {
+        StopReconcileTick();
         Result.TrySetResult(Tasks.Where(t => t.IsSelected).Select(t => t.Id).ToList());
         CloseAction?.Invoke();
     }
@@ -170,7 +194,17 @@ public sealed partial class MergeHelperSelectionModalViewModel : ViewModelBase
     [RelayCommand]
     private void Cancel()
     {
+        StopReconcileTick();
         Result.TrySetResult(null);
         CloseAction?.Invoke();
     }
+
+    // Also called from the dialog's native-close fallback (WindowDialogService), which resolves
+    // Result without going through Confirm/Cancel. Idempotent — Timer.Stop()/Dispose() tolerate
+    // repeated calls.
+    internal void StopReconcileTick()
+    {
+        _reconcileTimer.Stop();
+        _reconcileTimer.Dispose();
+    }
 }

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

@@ -100,8 +100,20 @@ public sealed partial class WorktreesOverviewModalViewModel : ViewModelBase
         _worker = worker;
         _diffVmFactory = diffVmFactory;
         _merge = merge;
+        // Phase 3 reconcile tick: this overlay is long-lived (stays open while the user reviews
+        // worktrees), so refresh it on the same cadence as TasksIslandViewModel's tick instead of
+        // leaving it frozen at the moment it was opened. Skipped while a load or batch merge is
+        // already in flight — reloading mid-merge would replace the row instances the merge loop
+        // is still updating.
+        _reconcileTimer.Elapsed += (_, _) =>
+            Avalonia.Threading.Dispatcher.UIThread.Post(() => _ = ReconcileTickAsync());
+        _reconcileTimer.Start();
     }
 
+    private readonly System.Timers.Timer _reconcileTimer = new(4_000);
+
+    internal Task ReconcileTickAsync() => IsBusy || IsMerging ? Task.CompletedTask : LoadAsync();
+
     public void SelectRow(WorktreeOverviewRowViewModel row)
     {
         if (SelectedRow is not null) SelectedRow.IsSelected = false;
@@ -179,7 +191,12 @@ public sealed partial class WorktreesOverviewModalViewModel : ViewModelBase
     }
 
     [RelayCommand]
-    private void Close() => CloseAction?.Invoke();
+    private void Close()
+    {
+        _reconcileTimer.Stop();
+        _reconcileTimer.Dispose();
+        CloseAction?.Invoke();
+    }
 
     [RelayCommand]
     private void ShowDiff(WorktreeOverviewRowViewModel? row)

src/ClaudeDo.Ui/Views/MainWindow.axaml.cs

@@ -25,7 +25,11 @@ public partial class MainWindow : Window
     {
         base.OnPropertyChanged(change);
         if (change.Property == WindowStateProperty)
+        {
             UpdateMaxIcon();
+            if (DataContext is IslandsShellViewModel vm && vm.Tasks is not null)
+                vm.Tasks.IsWindowVisible = WindowState != WindowState.Minimized;
+        }
         if (change.Property == OffScreenMarginProperty)
             RootGrid.Margin = OffScreenMargin;
     }
@@ -48,6 +52,8 @@ public partial class MainWindow : Window
                     WindowState = WindowState.Normal;
                 Activate();
             };
+            if (vm.Tasks is not null)
+                vm.Tasks.IsWindowVisible = WindowState != WindowState.Minimized;
         }
     }
 

src/ClaudeDo.Ui/Views/WindowDialogService.cs

@@ -94,7 +94,11 @@ public sealed class WindowDialogService : IDialogService
     {
         var dlg = new MergeHelperSelectionModal { DataContext = vm };
         vm.CloseAction = () => dlg.Close();
-        dlg.Closed += (_, _) => vm.Result.TrySetResult(null);   // native close counts as cancel
+        dlg.Closed += (_, _) =>
+        {
+            vm.StopReconcileTick();
+            vm.Result.TrySetResult(null);   // native close counts as cancel
+        };
         await dlg.ShowDialog(_owner);
         return await vm.Result.Task;
     }