refactor(worker): make the list-handler launch spec single-list and single-repo

src/ClaudeDo.Ui/Services/Interfaces/IWorkerClient.cs

@@ -86,8 +86,8 @@ public interface IWorkerClient : INotifyPropertyChanged
     /// no task, no worktree.</summary>
     Task<LaunchSpec> GetAdHocLaunchSpecAsync(string directory, CancellationToken ct = default);
     /// <summary>Launch spec for an embedded ConPTY "merge helper" session that drives the given
-    /// tasks to a merged/Done state. listId scopes the session to that list; null = all lists.</summary>
-    Task<LaunchSpec> GetMergeHelperLaunchSpecAsync(IReadOnlyList<string> taskIds, string? listId, CancellationToken ct = default);
+    /// tasks to a merged/Done state. listId scopes the session (and cwd) to that list.</summary>
+    Task<LaunchSpec> GetMergeHelperLaunchSpecAsync(IReadOnlyList<string> taskIds, string listId, CancellationToken ct = default);
     /// <summary>Starts a planning session and returns the launch spec for an embedded ConPTY
     /// planning terminal (replaces StartPlanningSessionAsync's external wt window).</summary>
     Task<LaunchSpec> GetPlanningStartLaunchSpecAsync(string taskId, CancellationToken ct = default);

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -522,7 +522,7 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
     public async Task<LaunchSpec> GetAdHocLaunchSpecAsync(string directory, CancellationToken ct = default)
         => await _hub.InvokeAsync<LaunchSpec>("GetAdHocLaunchSpec", directory, ct);
 
-    public async Task<LaunchSpec> GetMergeHelperLaunchSpecAsync(IReadOnlyList<string> taskIds, string? listId, CancellationToken ct = default)
+    public async Task<LaunchSpec> GetMergeHelperLaunchSpecAsync(IReadOnlyList<string> taskIds, string listId, CancellationToken ct = default)
         => await _hub.InvokeAsync<LaunchSpec>("GetMergeHelperLaunchSpec", taskIds, listId, ct);
 
     public async Task<LaunchSpec> GetPlanningStartLaunchSpecAsync(string taskId, CancellationToken ct = default)

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

@@ -16,8 +16,8 @@ namespace ClaudeDo.Ui.ViewModels.Islands;
 
 public enum ListKind { Smart, Virtual, User }
 
-/// <summary>Confirmed merge-helper run: the scope list (null = all lists) and the ordered selected task ids.</summary>
-public sealed record MergeHelperRequest(string? ListId, IReadOnlyList<string> TaskIds);
+/// <summary>Confirmed handler run: the scope list and the ordered selected task ids.</summary>
+public sealed record MergeHelperRequest(string ListId, IReadOnlyList<string> TaskIds);
 
 public sealed partial class ListsIslandViewModel : ViewModelBase, IDisposable
 {

src/ClaudeDo.Ui/ViewModels/MissionControlViewModel.cs

@@ -322,23 +322,20 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
         }
     }
 
-    // Merge-helper session over a hand-picked set of tasks ("Let Claude handle it").
+    // List-handler session over a hand-picked set of tasks ("Let Claude handle it").
     // Ad-hoc style: no owning task, never deduped — every run opens a fresh pane.
-    public async System.Threading.Tasks.Task OpenMergeHelperConPtySessionAsync(string? listId, IReadOnlyList<string> taskIds)
+    public async System.Threading.Tasks.Task OpenMergeHelperConPtySessionAsync(string listId, IReadOnlyList<string> taskIds)
     {
         if (taskIds is not { Count: > 0 }) return;
 
         var title = Loc.T("missionControl.mergeHelperTitle");
-        if (listId is not null)
+        try
         {
-            try
-            {
-                await using var ctx = await _dbFactory.CreateDbContextAsync();
-                var list = await ctx.Lists.AsNoTracking().FirstOrDefaultAsync(l => l.Id == listId);
-                if (list?.Name is { Length: > 0 } name) title = $"{title} — {name}";
-            }
-            catch { /* best-effort title lookup */ }
+            await using var ctx = await _dbFactory.CreateDbContextAsync();
+            var list = await ctx.Lists.AsNoTracking().FirstOrDefaultAsync(l => l.Id == listId);
+            if (list?.Name is { Length: > 0 } name) title = $"{title} — {name}";
         }
+        catch { /* best-effort title lookup */ }
 
         try
         {