feat(ui): add conflict resolution dialog for planning merge-all

Opens a modal when PlanningMergeConflict fires, listing conflicted files
with options to open in VS Code, continue, or abort the merge.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs

@@ -4,9 +4,12 @@ using System.Threading;
 using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using ClaudeDo.Data;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Ui.Services;
 using ClaudeDo.Ui.ViewModels.Islands;
+using ClaudeDo.Ui.ViewModels.Planning;
+using Microsoft.EntityFrameworkCore;
 
 namespace ClaudeDo.Ui.ViewModels;
 
@@ -27,6 +30,10 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
 
     private readonly UpdateCheckService _updateCheck;
     private readonly InstallerLocator _installerLocator;
+    private readonly IDbContextFactory<ClaudeDoDbContext>? _dbFactory;
+
+    // Set by MainWindow to open the conflict resolution dialog.
+    public Func<ConflictResolutionViewModel, Task>? ShowConflictDialog { get; set; }
 
     [ObservableProperty] private bool _isUpdateBannerVisible;
     [ObservableProperty] private string? _updateBannerLatestVersion;
@@ -84,6 +91,47 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         WorkerLogText = null;
     }
 
+    private void OnPlanningMergeConflict(string planningTaskId, string subtaskId, IReadOnlyList<string> conflictedFiles)
+    {
+        // Already on UI thread (WorkerClient dispatches via Dispatcher.UIThread.Post).
+        _ = OpenConflictDialogAsync(planningTaskId, subtaskId, conflictedFiles);
+    }
+
+    private async Task OpenConflictDialogAsync(string planningTaskId, string subtaskId, IReadOnlyList<string> conflictedFiles)
+    {
+        if (ShowConflictDialog == null || _dbFactory == null) return;
+
+        string subtaskTitle = subtaskId;
+        string worktreePath = System.Environment.CurrentDirectory;
+        string targetBranch = Worker?.LastMergeAllTarget ?? "main";
+
+        try
+        {
+            await using var ctx = await _dbFactory.CreateDbContextAsync();
+            var entity = await ctx.Tasks
+                .Include(t => t.Worktree)
+                .AsNoTracking()
+                .FirstOrDefaultAsync(t => t.Id == subtaskId);
+            if (entity != null)
+            {
+                subtaskTitle = entity.Title;
+                if (entity.Worktree?.Path is { } p)
+                    worktreePath = p;
+            }
+        }
+        catch { /* Non-fatal: fall back to subtaskId and cwd */ }
+
+        var vm = new ConflictResolutionViewModel(
+            Worker!,
+            planningTaskId,
+            subtaskTitle,
+            targetBranch,
+            conflictedFiles,
+            worktreePath);
+
+        await ShowConflictDialog(vm);
+    }
+
     // For tests only — does NOT wire up events.
     internal IslandsShellViewModel() { }
 
@@ -93,11 +141,13 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
         DetailsIslandViewModel details,
         WorkerClient worker,
         UpdateCheckService updateCheck,
-        InstallerLocator installerLocator)
+        InstallerLocator installerLocator,
+        IDbContextFactory<ClaudeDoDbContext> dbFactory)
     {
         Lists = lists; Tasks = tasks; Details = details; Worker = worker;
         _updateCheck = updateCheck;
         _installerLocator = installerLocator;
+        _dbFactory = dbFactory;
         Lists.SelectionChanged += (_, _) => Tasks.LoadForList(Lists.SelectedList);
         Tasks.SelectionChanged += (_, _) => Details.Bind(Tasks.SelectedTask);
         Tasks.TasksChanged     += (_, _) => _ = Lists.RefreshCountsAsync();
@@ -122,6 +172,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase
             }
         };
         Worker.WorkerLogReceivedEvent += OnWorkerLogReceived;
+        Worker.PlanningMergeConflictEvent += OnPlanningMergeConflict;
         _clearTimer.Elapsed += (_, _) =>
         {
             if (Dispatcher.UIThread.CheckAccess())