feat(ui): richer diff viewer + surface child roadblocks on parents

- UnifiedDiffParser detects added/deleted/renamed/binary files; diff
  modal shows a file list, binary/empty placeholders, and can diff a
  merged task by commit range after its worktree is gone
- DetailsIslandViewModel flags children needing attention (failed,
  cancelled, awaiting review, or with roadblocks) on the parent
- GitService gains worktree head-commit/range support; planning chain,
  merge orchestration, and session manager tweaks with updated tests
- refresh app/installer/worker icons

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -165,6 +165,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
     {
         OnPropertyChanged(nameof(HasChildOutcomes));
         OnPropertyChanged(nameof(ShowMergeSection));
+        NotifyAttention();
 
         // The Session tab is only visible when it has outcomes; if it just
         // emptied while selected, fall back to Output so the body isn't blank.
@@ -354,7 +355,11 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
 
     [ObservableProperty] private string? _worktreePath;
     [ObservableProperty] private string? _worktreeBaseCommit;
+    [ObservableProperty] private string? _worktreeHeadCommit;
     [ObservableProperty] private string? _worktreeStateLabel;
+    // Repo working dir of the selected task's list — used to diff a merged task's
+    // commit range after its worktree directory is gone.
+    private string? _listWorkingDir;
     [ObservableProperty] private string? _branchLine;
     [ObservableProperty] private int _turns;
     [ObservableProperty] private int _tokens;
@@ -388,6 +393,27 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
     public ObservableCollection<ChildOutcomeRowViewModel> ChildOutcomes { get; } = new();
     public bool HasChildOutcomes => ChildOutcomes.Count > 0;
 
+    // Children that need the user's attention before the parent can be approved:
+    // failed, cancelled, still awaiting their own review, or that reported roadblocks.
+    // The parent deliberately stays in WaitingForChildren until these are resolved;
+    // this surfaces a flag so the roadblock is visible on the parent.
+    public int ChildrenNeedingAttention => ChildOutcomes.Count(c =>
+        c.Status == ClaudeDo.Data.Models.TaskStatus.Failed
+        || c.Status == ClaudeDo.Data.Models.TaskStatus.Cancelled
+        || c.Status == ClaudeDo.Data.Models.TaskStatus.WaitingForReview
+        || c.RoadblockCount > 0);
+    public bool HasChildrenNeedingAttention => ChildrenNeedingAttention > 0;
+    public string ChildrenAttentionText => ChildrenNeedingAttention == 1
+        ? "1 child needs attention"
+        : $"{ChildrenNeedingAttention} children need attention";
+
+    private void NotifyAttention()
+    {
+        OnPropertyChanged(nameof(ChildrenNeedingAttention));
+        OnPropertyChanged(nameof(HasChildrenNeedingAttention));
+        OnPropertyChanged(nameof(ChildrenAttentionText));
+    }
+
     [ObservableProperty] private string _newSubtaskTitle = "";
 
     // Planning merge controls
@@ -840,6 +866,8 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             EditableDescription = "";
             Model = null;
             WorktreePath = null;
+            WorktreeHeadCommit = null;
+            _listWorkingDir = null;
             WorktreeStateLabel = null;
             BranchLine = null;
             DiffAdditions = 0;
@@ -876,6 +904,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             var entity = await ctx.Tasks
                 .AsNoTracking()
                 .Include(t => t.Worktree)
+                .Include(t => t.List)
                 .FirstOrDefaultAsync(t => t.Id == row.Id, ct);
             ct.ThrowIfCancellationRequested();
             if (entity == null) return;
@@ -885,8 +914,10 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             try { EditableDescription = entity.Description ?? ""; }
             finally { _suppressDescSave = false; }
             Model = entity.Model;
+            _listWorkingDir = entity.List?.WorkingDir;
             WorktreePath = entity.Worktree?.Path;
             WorktreeBaseCommit = entity.Worktree?.BaseCommit;
+            WorktreeHeadCommit = entity.Worktree?.HeadCommit;
             WorktreeStateLabel = entity.Worktree?.State.ToString();
             BranchLine = entity.Worktree is { } w ? $"{w.BranchName} \u2190 main" : null;
             var (add, del) = ParseDiffStat(entity.Worktree?.DiffStat);
@@ -914,13 +945,12 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
                 Subtasks.Add(new SubtaskRowViewModel { Id = s.Id, Title = s.Title, Done = s.Completed });
 
             if (entity.PlanningPhase != ClaudeDo.Data.Models.PlanningPhase.None)
-            {
                 await LoadPlanningChildrenAsync(row.Id, ct);
-            }
-            else
-            {
-                await LoadChildOutcomesAsync(row.Id, ct);
-            }
+            // Surface every parent's children — planning or improvement — in the
+            // Session tab with their live status + roadblock count. This is what
+            // makes the Session tab appear for planning parents and lets a child's
+            // roadblock register on the parent.
+            await LoadChildOutcomesAsync(row.Id, ct);
 
             if (entity.Worktree != null
                 && entity.PlanningPhase == ClaudeDo.Data.Models.PlanningPhase.None
@@ -1125,6 +1155,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             row.RoadblockCount = child.RoadblockCount;
             row.WorktreeState = child.Worktree?.State ?? ClaudeDo.Data.Models.WorktreeState.Active;
             ReviewCombinedDiffCommand.NotifyCanExecuteChanged();
+            NotifyAttention();
         }
         catch { /* best-effort */ }
     }
@@ -1148,11 +1179,14 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             var entity = await ctx.Tasks
                 .AsNoTracking()
                 .Include(t => t.Worktree)
+                .Include(t => t.List)
                 .FirstOrDefaultAsync(t => t.Id == taskId);
             if (entity == null || Task?.Id != taskId) return;
 
+            _listWorkingDir = entity.List?.WorkingDir;
             WorktreePath = entity.Worktree?.Path;
             WorktreeBaseCommit = entity.Worktree?.BaseCommit;
+            WorktreeHeadCommit = entity.Worktree?.HeadCommit;
             WorktreeStateLabel = entity.Worktree?.State.ToString();
             BranchLine = entity.Worktree is { } w ? $"{w.BranchName} ← main" : null;
             AgentState = StatusToStateKey(entity.Status);
@@ -1190,21 +1224,53 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
     [RelayCommand(CanExecute = nameof(CanOpenDiff))]
     private async System.Threading.Tasks.Task OpenDiffAsync()
     {
-        if (WorktreePath == null || ShowDiffModal == null) return;
-        var diffVm = new DiffModalViewModel(_services.GetRequiredService<ClaudeDo.Data.Git.GitService>())
+        if (ShowDiffModal == null) return;
+        var git = _services.GetRequiredService<ClaudeDo.Data.Git.GitService>();
+
+        // Active worktree on disk → diff the worktree live (and allow merging from it).
+        var hasLiveWorktree =
+            WorktreePath != null
+            && WorktreeStateLabel == "Active"
+            && System.IO.Directory.Exists(WorktreePath);
+
+        DiffModalViewModel diffVm;
+        if (hasLiveWorktree)
         {
-            WorktreePath = WorktreePath,
-            BaseRef = WorktreeBaseCommit,
-            TaskId = Task?.Id,
-            TaskTitle = Task?.Title ?? "",
-            ShowMergeModal = ShowMergeModal,
-            ResolveMergeVm = () => _services.GetRequiredService<MergeModalViewModel>(),
-        };
+            diffVm = new DiffModalViewModel(git)
+            {
+                WorktreePath = WorktreePath!,
+                BaseRef = WorktreeBaseCommit,
+                TaskId = Task?.Id,
+                TaskTitle = Task?.Title ?? "",
+                ShowMergeModal = ShowMergeModal,
+                ResolveMergeVm = () => _services.GetRequiredService<MergeModalViewModel>(),
+            };
+        }
+        else if (CanDiffMergedRange)
+        {
+            // Worktree is gone (merged/discarded) but the commits survive on the
+            // target branch — diff the captured base..head range in the repo. No
+            // merge action: the work is already integrated.
+            diffVm = new DiffModalViewModel(git)
+            {
+                WorktreePath = _listWorkingDir!,
+                BaseRef = WorktreeBaseCommit,
+                HeadCommit = WorktreeHeadCommit,
+                FromCommitRange = true,
+                TaskId = Task?.Id,
+                TaskTitle = Task?.Title ?? "",
+            };
+        }
+        else return;
+
         await diffVm.LoadAsync();
         await ShowDiffModal(diffVm);
     }
 
-    private bool CanOpenDiff() => WorktreePath != null;
+    private bool CanDiffMergedRange =>
+        WorktreeBaseCommit != null && WorktreeHeadCommit != null && _listWorkingDir != null;
+
+    private bool CanOpenDiff() => WorktreePath != null || CanDiffMergedRange;
 
     [RelayCommand(CanExecute = nameof(CanOpenWorktree))]
     private void OpenWorktree()
@@ -1235,6 +1301,9 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
         NotifySessionSections();
     }
 
+    partial void OnWorktreeHeadCommitChanged(string? value) =>
+        OpenDiffCommand.NotifyCanExecuteChanged();
+
     partial void OnTaskChanged(TaskRowViewModel? value) => NotifySessionSections();
 
     [RelayCommand]
@@ -1473,7 +1542,13 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             }
             // hasChildren: conflicts arrive via PlanningMergeConflictEvent → conflict dialog
         }
-        catch { /* stale review action; broadcast reconciles */ }
+        catch (Exception ex)
+        {
+            // A real failure (e.g. a child still needs attention, so the unit can't
+            // be approved yet) must not vanish — tell the user why nothing happened.
+            if (ShowErrorAsync != null)
+                await ShowErrorAsync(ex.Message);
+        }
     }
 
     [RelayCommand]

src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs

@@ -154,21 +154,23 @@ public sealed partial class IslandsShellViewModel : ViewModelBase, IDisposable
         if (ShowConflictDialog == null || _dbFactory == null) return;
 
         string subtaskTitle = subtaskId;
-        string worktreePath = System.Environment.CurrentDirectory;
+        // The conflict lives in the list's working dir (the repo being merged into),
+        // not the subtask worktree. VS Code must open this folder to show the merge UI.
+        string repoDirectory = System.Environment.CurrentDirectory;
         string targetBranch = Worker?.LastApproveTarget ?? "main";
 
         try
         {
             await using var ctx = await _dbFactory.CreateDbContextAsync();
             var entity = await ctx.Tasks
-                .Include(t => t.Worktree)
+                .Include(t => t.List)
                 .AsNoTracking()
                 .FirstOrDefaultAsync(t => t.Id == subtaskId);
             if (entity != null)
             {
                 subtaskTitle = entity.Title;
-                if (entity.Worktree?.Path is { } p)
-                    worktreePath = p;
+                if (entity.List?.WorkingDir is { } dir && !string.IsNullOrWhiteSpace(dir))
+                    repoDirectory = dir;
             }
         }
         catch { /* Non-fatal: fall back to subtaskId and cwd */ }
@@ -179,7 +181,7 @@ public sealed partial class IslandsShellViewModel : ViewModelBase, IDisposable
             subtaskTitle,
             targetBranch,
             conflictedFiles,
-            worktreePath);
+            repoDirectory);
 
         await ShowConflictDialog(vm);
     }

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

@@ -8,6 +8,8 @@ namespace ClaudeDo.Ui.ViewModels.Modals;
 
 public enum DiffLineKind { Add, Del, Ctx, File }
 
+public enum DiffFileStatus { Modified, Added, Deleted, Renamed }
+
 public sealed class DiffLineViewModel
 {
     public required DiffLineKind Kind { get; init; }
@@ -32,10 +34,27 @@ public sealed class DiffLineViewModel
 
 public sealed class DiffFileViewModel
 {
-    public required string Path { get; init; }
+    public required string Path { get; set; }
+    public string? OldPath { get; set; }
+    public DiffFileStatus Status { get; set; } = DiffFileStatus.Modified;
+    public bool IsBinary { get; set; }
     public int Additions { get; set; }
     public int Deletions { get; set; }
     public ObservableCollection<DiffLineViewModel> Lines { get; } = new();
+
+    /// Single-letter badge for the file's change kind (A/M/D/R).
+    public string StatusCode => Status switch
+    {
+        DiffFileStatus.Added    => "A",
+        DiffFileStatus.Deleted  => "D",
+        DiffFileStatus.Renamed  => "R",
+        _                       => "M",
+    };
+
+    public bool HasLines => Lines.Count > 0;
+
+    /// A text file that produced no diff hunks (e.g. a newly added empty file).
+    public bool IsEmptyContent => !IsBinary && Lines.Count == 0;
 }
 
 public sealed partial class DiffModalViewModel : ViewModelBase
@@ -44,6 +63,11 @@ public sealed partial class DiffModalViewModel : ViewModelBase
 
     public required string WorktreePath { get; init; }
     public string? BaseRef { get; init; }
+    /// When set together with <see cref="FromCommitRange"/>, the diff is computed as
+    /// <c>BaseRef..HeadCommit</c> inside <see cref="WorktreePath"/> (used as the repo
+    /// dir) — lets a merged task's diff be viewed after its worktree is gone.
+    public string? HeadCommit { get; init; }
+    public bool FromCommitRange { get; init; }
     public string? TaskId { get; init; }
     public string TaskTitle { get; init; } = "";
     public Func<MergeModalViewModel, Task>? ShowMergeModal { get; set; }
@@ -77,6 +101,8 @@ public sealed partial class DiffModalViewModel : ViewModelBase
         var vm = ResolveMergeVm();
         await vm.InitializeAsync(TaskId, TaskTitle);
         await ShowMergeModal(vm);
+        // The diff is stale once the worktree has been merged away — close it too.
+        if (vm.Merged) CloseAction?.Invoke();
     }
 
     public async Task LoadAsync(CancellationToken ct = default)
@@ -87,9 +113,11 @@ public sealed partial class DiffModalViewModel : ViewModelBase
         string raw;
         try
         {
-            raw = BaseRef is not null
-                ? await _git.GetBranchDiffAsync(WorktreePath, BaseRef, ct)
-                : await _git.GetDiffAsync(WorktreePath, ct);
+            raw = FromCommitRange && BaseRef is not null && HeadCommit is not null
+                ? await _git.GetCommitRangeDiffAsync(WorktreePath, BaseRef, HeadCommit, ct)
+                : BaseRef is not null
+                    ? await _git.GetBranchDiffAsync(WorktreePath, BaseRef, ct)
+                    : await _git.GetDiffAsync(WorktreePath, ct);
         }
         catch (Exception ex)
         {

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

@@ -28,6 +28,10 @@ public sealed partial class MergeModalViewModel : ViewModelBase
 
     public Action? CloseAction { get; set; }
 
+    /// True once a merge has succeeded — lets the caller (e.g. the diff window)
+    /// close itself after this modal closes.
+    public bool Merged { get; private set; }
+
     public MergeModalViewModel(WorkerClient worker)
     {
         _worker = worker;
@@ -80,6 +84,7 @@ public sealed partial class MergeModalViewModel : ViewModelBase
             switch (result.Status)
             {
                 case "merged":
+                    Merged = true;
                     SuccessMessage = result.ErrorMessage is not null
                         ? $"Merged with warning: {result.ErrorMessage}"
                         : Loc.T("vm.merge.merged");

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

@@ -27,6 +27,36 @@ public static class UnifiedDiffParser
 
             if (current == null) continue;
 
+            // File-level metadata that carries the change kind.
+            if (line.StartsWith("new file", StringComparison.Ordinal))
+            {
+                current.Status = DiffFileStatus.Added;
+                continue;
+            }
+            if (line.StartsWith("deleted file", StringComparison.Ordinal))
+            {
+                current.Status = DiffFileStatus.Deleted;
+                continue;
+            }
+            if (line.StartsWith("rename from ", StringComparison.Ordinal))
+            {
+                current.Status = DiffFileStatus.Renamed;
+                current.OldPath = line["rename from ".Length..];
+                continue;
+            }
+            if (line.StartsWith("rename to ", StringComparison.Ordinal))
+            {
+                current.Status = DiffFileStatus.Renamed;
+                current.Path = line["rename to ".Length..];
+                continue;
+            }
+            if (line.StartsWith("Binary files", StringComparison.Ordinal) ||
+                line.StartsWith("GIT binary patch", StringComparison.Ordinal))
+            {
+                current.IsBinary = true;
+                continue;
+            }
+
             if (line.StartsWith("@@ ", StringComparison.Ordinal))
             {
                 // e.g. "@@ -10,7 +10,9 @@"
@@ -34,13 +64,15 @@ public static class UnifiedDiffParser
                 continue;
             }
 
-            // Skip diff metadata lines
+            // Skip remaining diff metadata lines
             if (line.StartsWith("--- ", StringComparison.Ordinal) ||
                 line.StartsWith("+++ ", StringComparison.Ordinal) ||
                 line.StartsWith("index ", StringComparison.Ordinal) ||
-                line.StartsWith("new file", StringComparison.Ordinal) ||
-                line.StartsWith("deleted file", StringComparison.Ordinal) ||
-                line.StartsWith("Binary ", StringComparison.Ordinal))
+                line.StartsWith("old mode", StringComparison.Ordinal) ||
+                line.StartsWith("new mode", StringComparison.Ordinal) ||
+                line.StartsWith("similarity index", StringComparison.Ordinal) ||
+                line.StartsWith("copy from", StringComparison.Ordinal) ||
+                line.StartsWith("copy to", StringComparison.Ordinal))
                 continue;
 
             if (line.StartsWith('+'))

src/ClaudeDo.Ui/ViewModels/Planning/ConflictResolutionViewModel.cs

@@ -10,7 +10,10 @@ public sealed partial class ConflictResolutionViewModel : ObservableObject
 {
     private readonly IWorkerClient _worker;
     private readonly string _planningTaskId;
-    private readonly string _worktreePath;
+    // The repository directory that is currently mid-merge (the list's working dir),
+    // NOT the subtask worktree. Opening this folder is what makes VS Code show its
+    // merge-conflict resolution UI.
+    private readonly string _repoDirectory;
 
     public string SubtaskTitle { get; }
     public string TargetBranch { get; }
@@ -29,11 +32,11 @@ public sealed partial class ConflictResolutionViewModel : ObservableObject
         string subtaskTitle,
         string targetBranch,
         IReadOnlyList<string> conflictedFiles,
-        string worktreePath)
+        string repoDirectory)
     {
         _worker = worker;
         _planningTaskId = planningTaskId;
-        _worktreePath = worktreePath;
+        _repoDirectory = repoDirectory;
         SubtaskTitle = subtaskTitle;
         TargetBranch = targetBranch;
         ConflictedFiles = conflictedFiles;
@@ -44,12 +47,13 @@ public sealed partial class ConflictResolutionViewModel : ObservableObject
     {
         try
         {
-            var args = string.Join(" ", ConflictedFiles.Select(f => $"\"{f}\""));
+            // Open the folder that is mid-merge so VS Code shows the Source Control
+            // merge-conflict UI for every conflicted file. Opening individual files
+            // gives only a plain editor with no conflict resolution affordances.
             Process.Start(new ProcessStartInfo
             {
                 FileName = "code",
-                Arguments = args,
-                WorkingDirectory = _worktreePath,
+                Arguments = $"\"{_repoDirectory}\"",
                 UseShellExecute = true,
             });
             VsCodeError = null;