feat(ui): show mergeability and surface approve conflicts in the work console

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

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

@@ -339,6 +339,24 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     [ObservableProperty] private string? _mergeAllDisabledReason;
     [ObservableProperty] private string? _mergeAllError;
 
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ShowMergePreviewMuted))]
+    private string _mergePreviewText = "";
+
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ShowMergePreviewMuted))]
+    private bool _mergeIsClean;
+
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ShowMergePreviewMuted))]
+    private bool _mergeIsConflict;
+
+    public bool ShowMergePreviewMuted =>
+        !MergeIsClean && !MergeIsConflict && !string.IsNullOrEmpty(MergePreviewText);
+
+    public bool ShowSingleMerge =>
+        WorktreePath != null && Task?.IsPlanningParent != true;
+
     // Claude CLI stream-json parser + buffer for partial text deltas
     private readonly StreamLineFormatter _formatter = new();
     private readonly StringBuilder _claudeBuf = new();
@@ -812,6 +830,20 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
             {
                 await LoadChildOutcomesAsync(row.Id, ct);
             }
+
+            if (entity.Worktree != null
+                && entity.PlanningPhase == ClaudeDo.Data.Models.PlanningPhase.None
+                && MergeTargetBranches.Count == 0)
+            {
+                var targets = await _worker.GetMergeTargetsAsync(row.Id);
+                if (targets != null)
+                {
+                    MergeTargetBranches.Clear();
+                    foreach (var b in targets.LocalBranches) MergeTargetBranches.Add(b);
+                    SelectedMergeTarget = targets.DefaultBranch; // triggers OnSelectedMergeTargetChanged → preview
+                }
+            }
+            await RefreshMergePreviewAsync();
         }
         catch (OperationCanceledException) { }
     }
@@ -1102,6 +1134,45 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
         catch { /* best-effort refresh */ }
     }
 
+    private async System.Threading.Tasks.Task RefreshMergePreviewAsync()
+    {
+        if (Task is null || WorktreePath is null)
+        {
+            MergePreviewText = ""; MergeIsClean = false; MergeIsConflict = false;
+            return;
+        }
+        // Only probe Active worktrees; terminal states show their label instead.
+        if (WorktreeStateLabel is { } label && label != "Active")
+        {
+            MergePreviewText = label; MergeIsClean = false; MergeIsConflict = false;
+            return;
+        }
+        var dto = await _worker.PreviewMergeAsync(Task.Id, SelectedMergeTarget ?? "");
+        var (text, clean, conflict) = MergePreviewPresenter.Describe(dto);
+        MergePreviewText = text; MergeIsClean = clean; MergeIsConflict = conflict;
+    }
+
+    [RelayCommand]
+    private async System.Threading.Tasks.Task MergeAsync()
+    {
+        if (Task is null || WorktreePath is null || !_worker.IsConnected) return;
+        try
+        {
+            var result = await _worker.MergeTaskAsync(Task.Id, SelectedMergeTarget ?? "", false, "Merge task");
+            if (result.Status == "conflict")
+            {
+                var (text, _, _) = MergePreviewPresenter.Describe(
+                    new MergePreviewDto("conflict", result.ConflictFiles, 0));
+                MergePreviewText = text; MergeIsClean = false; MergeIsConflict = true;
+            }
+            else
+            {
+                await RefreshMergePreviewAsync();
+            }
+        }
+        catch { /* broadcast reconciles */ }
+    }
+
     [RelayCommand(CanExecute = nameof(CanOpenDiff))]
     private async System.Threading.Tasks.Task OpenDiffAsync()
     {
@@ -1138,11 +1209,17 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
 
     private bool CanOpenWorktree() => WorktreePath != null;
 
+    partial void OnSelectedMergeTargetChanged(string? value)
+    {
+        _ = RefreshMergePreviewAsync();
+    }
+
     partial void OnWorktreePathChanged(string? value)
     {
         OpenDiffCommand.NotifyCanExecuteChanged();
         OpenWorktreeCommand.NotifyCanExecuteChanged();
         NotifySessionSections();
+        OnPropertyChanged(nameof(ShowSingleMerge));
     }
 
     partial void OnTaskChanged(TaskRowViewModel? value) => NotifySessionSections();
@@ -1362,10 +1439,16 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     private async System.Threading.Tasks.Task ApproveReviewAsync()
     {
         if (Task is null || !_worker.IsConnected) return;
-        // The hub rejects (HubException) if the task is no longer WaitingForReview
+        try
-        // — e.g. after "Merge all" folded the parent. Swallow it; the TaskUpdated
+        {
-        // broadcast reconciles the UI. An unhandled command exception would crash.
+            var result = await _worker.ApproveReviewAsync(Task.Id, SelectedMergeTarget ?? "");
-        try { await _worker.ApproveReviewAsync(Task.Id, SelectedMergeTarget ?? ""); }
+            if (result?.Status == "conflict")
+            {
+                var (text, _, _) = MergePreviewPresenter.Describe(
+                    new MergePreviewDto("conflict", result.ConflictFiles, 0));
+                MergePreviewText = text; MergeIsClean = false; MergeIsConflict = true;
+            }
+        }
         catch { /* stale review action; broadcast reconciles */ }
     }
 

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

@@ -0,0 +1,28 @@
+using System.Linq;
+using ClaudeDo.Ui.Services;
+
+namespace ClaudeDo.Ui.ViewModels.Islands;
+
+/// Pure mapping from a merge-preview DTO to display text + color flags.
+public static class MergePreviewPresenter
+{
+    public static (string Text, bool IsClean, bool IsConflict) Describe(MergePreviewDto? dto)
+    {
+        if (dto is null) return ("", false, false);
+
+        switch (dto.Status)
+        {
+            case "clean":
+                var unit = dto.ChangedFileCount == 1 ? "file" : "files";
+                return ($"Merges cleanly · {dto.ChangedFileCount} {unit}", true, false);
+
+            case "conflict":
+                var names = string.Join(", ", dto.ConflictFiles.Take(3));
+                var more = dto.ConflictFiles.Count > 3 ? $" (+{dto.ConflictFiles.Count - 3} more)" : "";
+                return ($"Conflicts in {names}{more}", false, true);
+
+            default:
+                return ("Mergeability unknown", false, false);
+        }
+    }
+}

tests/ClaudeDo.Ui.Tests/ViewModels/MergePreviewPresenterTests.cs

@@ -0,0 +1,62 @@
+using ClaudeDo.Ui.Services;
+using ClaudeDo.Ui.ViewModels.Islands;
+
+namespace ClaudeDo.Ui.Tests.ViewModels;
+
+public class MergePreviewPresenterTests
+{
+    [Fact]
+    public void Clean_Plural()
+    {
+        var (text, clean, conflict) = MergePreviewPresenter.Describe(
+            new MergePreviewDto("clean", System.Array.Empty<string>(), 3));
+        Assert.Equal("Merges cleanly · 3 files", text);
+        Assert.True(clean);
+        Assert.False(conflict);
+    }
+
+    [Fact]
+    public void Clean_Singular()
+    {
+        var (text, _, _) = MergePreviewPresenter.Describe(
+            new MergePreviewDto("clean", System.Array.Empty<string>(), 1));
+        Assert.Equal("Merges cleanly · 1 file", text);
+    }
+
+    [Fact]
+    public void Conflict_ListsUpToThree()
+    {
+        var (text, clean, conflict) = MergePreviewPresenter.Describe(
+            new MergePreviewDto("conflict", new[] { "a.cs", "b.cs" }, 0));
+        Assert.Equal("Conflicts in a.cs, b.cs", text);
+        Assert.False(clean);
+        Assert.True(conflict);
+    }
+
+    [Fact]
+    public void Conflict_TruncatesWithMore()
+    {
+        var (text, _, _) = MergePreviewPresenter.Describe(
+            new MergePreviewDto("conflict", new[] { "a", "b", "c", "d", "e" }, 0));
+        Assert.Equal("Conflicts in a, b, c (+2 more)", text);
+    }
+
+    [Fact]
+    public void Unavailable_IsMuted()
+    {
+        var (text, clean, conflict) = MergePreviewPresenter.Describe(
+            new MergePreviewDto("unavailable", System.Array.Empty<string>(), 0));
+        Assert.Equal("Mergeability unknown", text);
+        Assert.False(clean);
+        Assert.False(conflict);
+    }
+
+    [Fact]
+    public void Null_IsEmpty()
+    {
+        var (text, clean, conflict) = MergePreviewPresenter.Describe(null);
+        Assert.Equal("", text);
+        Assert.False(clean);
+        Assert.False(conflict);
+    }
+}