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
         {

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -678,8 +678,8 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
 
     // Builds the launch spec for an embedded ConPTY "merge helper" session that drives the given
     // tasks to a merged/Done state via the mcp__claudedo__* tools. listId scopes the brief label
-    // and cwd to that list; null means all lists.
-    public Task<LaunchSpec> GetMergeHelperLaunchSpec(string[] taskIds, string? listId) => HubGuard(() =>
+    // and cwd to that list.
+    public Task<LaunchSpec> GetMergeHelperLaunchSpec(string[] taskIds, string listId) => HubGuard(() =>
     {
         if (_interactiveLaunchSpec is null)
             throw new InvalidOperationException("Interactive launch spec service is not configured.");

src/ClaudeDo.Worker/Runner/InteractiveLaunchSpecService.cs

@@ -163,51 +163,28 @@ public sealed class InteractiveLaunchSpecService : IInteractiveLaunchSpecService
     private const string MergeHelperAllowedTools =
         "mcp__claudedo__*,Read,Grep,Glob,Edit,Bash,WebFetch,WebSearch,Skill";
 
-    public async Task<LaunchSpec> BuildForMergeHelperAsync(IReadOnlyList<string> taskIds, string? listId, CancellationToken ct)
+    public async Task<LaunchSpec> BuildForMergeHelperAsync(IReadOnlyList<string> taskIds, string listId, CancellationToken ct)
     {
         if (taskIds.Count == 0)
-            throw new InvalidOperationException("No tasks selected for the merge helper.");
+            throw new InvalidOperationException("No tasks selected for the list handler.");
 
         await using var ctx = await _dbFactory.CreateDbContextAsync(ct);
         var taskRepo = new TaskRepository(ctx);
         var listRepo = new ListRepository(ctx);
 
-        var listsById = new Dictionary<string, ListEntity?>();
-        var briefLines = new List<string>();
-        var repoDirs = new List<string>(); // distinct, existing, in first-seen order
+        var list = await listRepo.GetByIdAsync(listId, ct)
+            ?? throw new KeyNotFoundException($"List not found: {listId}");
 
+        var repoDir = list.WorkingDir;
+        if (string.IsNullOrEmpty(repoDir) || !Directory.Exists(repoDir))
+            throw new InvalidOperationException($"list '{list.Name}' has no existing working directory");
+
+        var briefLines = new List<string>();
         foreach (var id in taskIds)
         {
             var task = await taskRepo.GetByIdAsync(id, ct)
                 ?? throw new KeyNotFoundException($"Task not found: {id}");
-            if (!listsById.TryGetValue(task.ListId, out var list))
-                listsById[task.ListId] = list = await listRepo.GetByIdAsync(task.ListId, ct);
-
-            var workingDir = list?.WorkingDir;
-            if (!string.IsNullOrEmpty(workingDir) && Directory.Exists(workingDir) && !repoDirs.Contains(workingDir))
-                repoDirs.Add(workingDir);
-
-            briefLines.Add(
-                $"- [{task.Status}] {task.Title} (id: {task.Id}, list: {list?.Name ?? "—"}, " +
-                $"repo: {(string.IsNullOrEmpty(workingDir) ? "—" : workingDir)})");
-        }
-
-        if (repoDirs.Count == 0)
-            throw new InvalidOperationException("none of the selected tasks are in a working directory");
-
-        string scopeLabel;
-        string cwd;
-        if (listId is not null)
-        {
-            var scopeList = await listRepo.GetByIdAsync(listId, ct)
-                ?? throw new KeyNotFoundException($"List not found: {listId}");
-            scopeLabel = $"List: {scopeList.Name}";
-            cwd = scopeList.WorkingDir is { Length: > 0 } wd && Directory.Exists(wd) ? wd : repoDirs[0];
-        }
-        else
-        {
-            scopeLabel = "All lists";
-            cwd = repoDirs[0];
+            briefLines.Add($"- [{task.Status}] {task.Title} (id: {task.Id})");
         }
 
         var sessionDir = Path.Combine(Paths.AppDataRoot(), "merge-helper-sessions", Guid.NewGuid().ToString());
@@ -220,7 +197,8 @@ public sealed class InteractiveLaunchSpecService : IInteractiveLaunchSpecService
         await File.WriteAllTextAsync(briefPath, PromptFiles.Render(PromptKind.MergeHelperInitial,
             new Dictionary<string, string>
             {
-                ["scope"] = scopeLabel,
+                ["scope"] = $"List: {list.Name}",
+                ["repo"] = repoDir,
                 ["tasks"] = string.Join("\n", briefLines),
             }), ct);
 
@@ -235,21 +213,18 @@ public sealed class InteractiveLaunchSpecService : IInteractiveLaunchSpecService
         {
             "--permission-mode", "default",
             "--allowedTools", MergeHelperAllowedTools,
-            "--add-dir", sessionDir,
+            "--add-dir", sessionDir, repoDir,
+            "--append-system-prompt-file", systemPromptPath,
+            $"Read the file {briefPath} first. It lists the tasks you must handle and their status. " +
+            "After reading it, begin the session as your instructions describe.",
         };
-        args.AddRange(repoDirs);
-        args.Add("--append-system-prompt-file");
-        args.Add(systemPromptPath);
-        args.Add(
-            $"Read the file {briefPath} first. It lists the tasks you must merge and their status. " +
-            "After reading it, begin the merge-helper session as your instructions describe.");
 
         var env = new Dictionary<string, string>
         {
             ["MCP_TOOL_TIMEOUT"] = "200000",
         };
 
-        return new LaunchSpec(cwd, resolvedClaude, args, env);
+        return new LaunchSpec(repoDir, resolvedClaude, args, env);
     }
 
     // The positional prompt claude opens the interactive session on. Empty (no positional arg)

src/ClaudeDo.Worker/Runner/Interfaces/IInteractiveLaunchSpecService.cs

@@ -30,8 +30,8 @@ public interface IInteractiveLaunchSpecService
     /// <summary>Builds a LaunchSpec for an embedded ConPTY "merge helper" session that drives the
     /// given tasks to a merged/Done state via the mcp__claudedo__* tools. Writes a per-session
     /// system prompt + task brief under ~/.todo-app/merge-helper-sessions/&lt;guid&gt; and exposes
-    /// that dir plus every distinct existing repo dir via --add-dir. listId scopes the brief label
-    /// and the cwd to that list; null means all lists (cwd = first existing repo dir). Throws
-    /// InvalidOperationException if taskIds is empty or no task has an existing working directory.</summary>
-    Task<LaunchSpec> BuildForMergeHelperAsync(IReadOnlyList<string> taskIds, string? listId, CancellationToken ct);
+    /// that dir plus the list's repo dir via --add-dir. cwd is the list's working directory.
+    /// Throws KeyNotFoundException if the list doesn't exist; InvalidOperationException if
+    /// taskIds is empty or the list has no existing working directory.</summary>
+    Task<LaunchSpec> BuildForMergeHelperAsync(IReadOnlyList<string> taskIds, string listId, CancellationToken ct);
 }