feat(ui): worker client surface for in-app interactive sessions

Adds SendInteractiveMessageAsync/StopInteractiveSessionAsync and the
InteractiveSessionStarted/Ended events to IWorkerClient + WorkerClient
(UI-thread dispatch mirroring TaskQuestionAsked). Updates the IWorkerClient
fakes in both test projects.

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

@@ -25,6 +25,9 @@ public interface IWorkerClient : INotifyPropertyChanged
     /// <summary>A pending question was answered, timed out, or the run ended: (taskId, questionId).</summary>
     event Action<string, string>? TaskQuestionResolvedEvent;
 
+    event Action<string>? InteractiveSessionStartedEvent;
+    event Action<string>? InteractiveSessionEndedEvent;
+
     event Action? PrepStartedEvent;
     event Action<string>? PrepLineEvent;
     event Action<bool>? PrepFinishedEvent;
@@ -46,6 +49,8 @@ public interface IWorkerClient : INotifyPropertyChanged
     Task ContinueTaskAsync(string taskId, string followUpPrompt);
     /// <summary>Answer a question a running task raised via AskUser.</summary>
     Task AnswerTaskQuestionAsync(string taskId, string questionId, string answer);
+    Task SendInteractiveMessageAsync(string taskId, string text);
+    Task StopInteractiveSessionAsync(string taskId);
     /// <summary>The question a running task is currently blocked on, if any (for re-attach).</summary>
     Task<PendingQuestionDto?> GetPendingQuestionAsync(string taskId);
     Task ResetTaskAsync(string taskId);

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -49,6 +49,8 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
     public event Action<string>? TaskUpdatedEvent;
     public event Action<string, string, string>? TaskQuestionAskedEvent;
     public event Action<string, string>? TaskQuestionResolvedEvent;
+    public event Action<string>? InteractiveSessionStartedEvent;
+    public event Action<string>? InteractiveSessionEndedEvent;
     public event Action? ConnectionRestoredEvent;
     public event Action<string>? WorktreeUpdatedEvent;
     public event Action<string>? ListUpdatedEvent;
@@ -148,6 +150,16 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
             Dispatcher.UIThread.Post(() => TaskQuestionResolvedEvent?.Invoke(taskId, questionId));
         });
 
+        _hub.On<string>("InteractiveSessionStarted", taskId =>
+        {
+            Dispatcher.UIThread.Post(() => InteractiveSessionStartedEvent?.Invoke(taskId));
+        });
+
+        _hub.On<string>("InteractiveSessionEnded", taskId =>
+        {
+            Dispatcher.UIThread.Post(() => InteractiveSessionEndedEvent?.Invoke(taskId));
+        });
+
         _hub.On<string>("WorktreeUpdated", taskId =>
         {
             Dispatcher.UIThread.Post(() => WorktreeUpdatedEvent?.Invoke(taskId));
@@ -279,6 +291,18 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
         catch { /* offline or already resolved — the UI clears optimistically */ }
     }
 
+    public async Task SendInteractiveMessageAsync(string taskId, string text)
+    {
+        try { await _hub.InvokeAsync("SendInteractiveMessage", taskId, text); }
+        catch { /* offline or session already ended */ }
+    }
+
+    public async Task StopInteractiveSessionAsync(string taskId)
+    {
+        try { await _hub.InvokeAsync("StopInteractiveSession", taskId); }
+        catch { /* offline */ }
+    }
+
     public Task<PendingQuestionDto?> GetPendingQuestionAsync(string taskId)
         => TryInvokeAsync<PendingQuestionDto>("GetPendingQuestion", taskId);
 

tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs

@@ -25,6 +25,8 @@ public abstract class StubWorkerClient : IWorkerClient
     public event Action<WorkerLogEntry>? WorkerLogReceivedEvent;
     public event Action<string, string, string>? TaskQuestionAskedEvent;
     public event Action<string, string>? TaskQuestionResolvedEvent;
+    public event Action<string>? InteractiveSessionStartedEvent;
+    public event Action<string>? InteractiveSessionEndedEvent;
     public event Action? PrepStartedEvent;
     public event Action<string>? PrepLineEvent;
     public event Action<bool>? PrepFinishedEvent;
@@ -133,6 +135,8 @@ public abstract class StubWorkerClient : IWorkerClient
     public virtual Task SetOnlineInboxConfigAsync(OnlineInboxConfigInputDto input) => Task.CompletedTask;
     public virtual Task SetOnlineInboxAuthAsync(string refreshToken) => Task.CompletedTask;
     public virtual Task ClearOnlineInboxAuthAsync() => Task.CompletedTask;
+    public virtual Task SendInteractiveMessageAsync(string taskId, string text) => Task.CompletedTask;
+    public virtual Task StopInteractiveSessionAsync(string taskId) => Task.CompletedTask;
 
     protected void RaisePropertyChanged(string name) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
 }

tests/ClaudeDo.Worker.Tests/UiVm/TasksIslandViewModelPlanningTests.cs

@@ -36,6 +36,8 @@ sealed class FakeWorkerClient : IWorkerClient
     public event Action<WorkerLogEntry>? WorkerLogReceivedEvent;
     public event Action<string, string, string>? TaskQuestionAskedEvent;
     public event Action<string, string>? TaskQuestionResolvedEvent;
+    public event Action<string>? InteractiveSessionStartedEvent;
+    public event Action<string>? InteractiveSessionEndedEvent;
     public void RaiseTaskUpdated(string taskId) => TaskUpdatedEvent?.Invoke(taskId);
     public void RaiseWorktreeUpdated(string taskId) => WorktreeUpdatedEvent?.Invoke(taskId);
     public void RaiseTaskMessage(string taskId, string line) => TaskMessageEvent?.Invoke(taskId, line);
@@ -122,6 +124,8 @@ sealed class FakeWorkerClient : IWorkerClient
     public Task SetOnlineInboxConfigAsync(OnlineInboxConfigInputDto input) => Task.CompletedTask;
     public Task SetOnlineInboxAuthAsync(string refreshToken) => Task.CompletedTask;
     public Task ClearOnlineInboxAuthAsync() => Task.CompletedTask;
+    public Task SendInteractiveMessageAsync(string taskId, string text) => Task.CompletedTask;
+    public Task StopInteractiveSessionAsync(string taskId) => Task.CompletedTask;
     public IReadOnlyList<ActiveTask> GetActiveTasks() => System.Array.Empty<ActiveTask>();
 }