diff --git a/src/ClaudeDo.Data/Wire.cs b/src/ClaudeDo.Data/Wire.cs
index 91a6474d..5d119d62 100644
--- a/src/ClaudeDo.Data/Wire.cs
+++ b/src/ClaudeDo.Data/Wire.cs
@@ -217,6 +217,10 @@ public sealed record LaunchSpec(
     IReadOnlyList<string> Args,
     IReadOnlyDictionary<string, string> Env);
 
+// A handler round's still-open (Queued/Running) task, for the Mission Control "abandon run"
+// action -- confirms with a count, then cancels each one before closing the pane.
+public record HandlerOpenTaskDto(string Id, string Title);
+
 public record TicketSettingsDto(string? ApiBaseUrl, bool TokenSet);
 public record TicketConnectionDto(bool Ok, string? UserName, IReadOnlyList<string> Scopes, string? Error);
 public record TicketProjectDto(int Id, string Title, string DepartmentName);
diff --git a/src/ClaudeDo.Localization/locales/de.json b/src/ClaudeDo.Localization/locales/de.json
index 1246018e..c5f0498a 100644
--- a/src/ClaudeDo.Localization/locales/de.json
+++ b/src/ClaudeDo.Localization/locales/de.json
@@ -354,6 +354,10 @@
     "enqueueAlreadyOpen": "Kann nicht in die Warteschlange gestellt werden — dieser Task hat eine offene interaktive Sitzung.",
     "enqueueFailed": "In die Warteschlange stellen fehlgeschlagen: {0}",
     "queueRefreshFailed": "Warteschlange konnte nicht aktualisiert werden: {0}",
+    "abandonRun": "Lauf abbrechen",
+    "abandonRunTip": "Die noch offenen Tasks dieses Laufs abbrechen und die Sitzung schließen",
+    "abandonRunConfirm": "{0} offene(n) Task(s) abbrechen und diese Sitzung schließen? Tasks im Review oder bereits erledigt bleiben unangetastet.",
+    "abandonRunFailed": "Offene Tasks konnten nicht abgebrochen werden: {0}",
     "question": {
       "title": "Claude fragt nach",
       "placeholder": "Antwort eingeben…",
diff --git a/src/ClaudeDo.Localization/locales/en.json b/src/ClaudeDo.Localization/locales/en.json
index bbd8f170..3b9b3c3e 100644
--- a/src/ClaudeDo.Localization/locales/en.json
+++ b/src/ClaudeDo.Localization/locales/en.json
@@ -354,6 +354,10 @@
     "enqueueAlreadyOpen": "Can't queue — this task has an open interactive session.",
     "enqueueFailed": "Queue failed: {0}",
     "queueRefreshFailed": "Couldn't refresh the queue: {0}",
+    "abandonRun": "Abandon run",
+    "abandonRunTip": "Cancel this run's still-open tasks and close the session",
+    "abandonRunConfirm": "Cancel {0} open task(s) and close this session? Tasks already in review or done are not affected.",
+    "abandonRunFailed": "Couldn't cancel the open tasks: {0}",
     "question": {
       "title": "Claude is asking",
       "placeholder": "Type your answer…",
diff --git a/src/ClaudeDo.Ui/Services/Interfaces/IWorkerClient.cs b/src/ClaudeDo.Ui/Services/Interfaces/IWorkerClient.cs
index 77e7a93c..ea823223 100644
--- a/src/ClaudeDo.Ui/Services/Interfaces/IWorkerClient.cs
+++ b/src/ClaudeDo.Ui/Services/Interfaces/IWorkerClient.cs
@@ -158,6 +158,10 @@ public interface IWorkerClient : INotifyPropertyChanged
     /// running. The exit code only exists in this process; the worker decides whether it was a
     /// list-handler session killed by the usage limit and reopens the same phase after the 5h reset.</summary>
     Task ReportInteractiveSessionExitedAsync(string taskId, int exitCode, CancellationToken ct = default);
+    /// <summary>The handler round's still-open (Queued/Running) tasks, for the Mission Control
+    /// "abandon run" action. Empty when the round has no entry or nothing open -- the caller then
+    /// closes the pane without a confirmation dialog.</summary>
+    Task<IReadOnlyList<HandlerOpenTaskDto>> GetHandlerOpenTasksAsync(string handlerTaskId, 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);
diff --git a/src/ClaudeDo.Ui/Services/WorkerClient.cs b/src/ClaudeDo.Ui/Services/WorkerClient.cs
index 85860146..b0230d65 100644
--- a/src/ClaudeDo.Ui/Services/WorkerClient.cs
+++ b/src/ClaudeDo.Ui/Services/WorkerClient.cs
@@ -641,6 +641,9 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
     public Task ReportInteractiveSessionExitedAsync(string taskId, int exitCode, CancellationToken ct = default)
         => InvokeTimedAsync("ReportInteractiveSessionExited", () => _hub.InvokeAsync("ReportInteractiveSessionExited", taskId, exitCode, ct));
 
+    public async Task<IReadOnlyList<HandlerOpenTaskDto>> GetHandlerOpenTasksAsync(string handlerTaskId, CancellationToken ct = default)
+        => await InvokeTimedAsync<List<HandlerOpenTaskDto>>("GetHandlerOpenTasks", () => _hub.InvokeAsync<List<HandlerOpenTaskDto>>("GetHandlerOpenTasks", handlerTaskId, ct));
+
     public async Task<LaunchSpec> GetPlanningStartLaunchSpecAsync(string taskId, CancellationToken ct = default)
         => await InvokeTimedAsync<LaunchSpec>("GetPlanningStartLaunchSpec", () => _hub.InvokeAsync<LaunchSpec>("GetPlanningStartLaunchSpec", taskId, ct));
 
diff --git a/src/ClaudeDo.Ui/ViewModels/MissionControl/ConPtyPaneViewModel.cs b/src/ClaudeDo.Ui/ViewModels/MissionControl/ConPtyPaneViewModel.cs
index e930850d..5737ccd9 100644
--- a/src/ClaudeDo.Ui/ViewModels/MissionControl/ConPtyPaneViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/MissionControl/ConPtyPaneViewModel.cs
@@ -18,6 +18,12 @@ public sealed partial class ConPtyPaneViewModel : ViewModelBase, IDisposable
     // Only a task-based pane can be submitted for review (an ad-hoc directory session has no task).
     public bool IsTaskBased => TaskId is not null;
 
+    /// <summary>Set by the host for a list-handler run ("Let Claude handle it" / "Let Claude merge
+    /// the reviews") pane -- shows the "Abandon run" action. Plain mutable property, not
+    /// <see cref="ObservableProperty"/>: the host sets it once right after construction, before the
+    /// pane is added to the visible collection, so no change notification is needed.</summary>
+    public bool IsListHandler { get; set; }
+
     [ObservableProperty] private string _displayTitle;
 
     [ObservableProperty] private InteractiveTerminalViewModel _terminal = new();
@@ -26,6 +32,10 @@ public sealed partial class ConPtyPaneViewModel : ViewModelBase, IDisposable
     /// flight, so a rapid double-click can't race two submissions for the same task.</summary>
     [ObservableProperty] private bool _isSubmitPending;
 
+    /// <summary>Set by the host while an abandon-run round trip (query open tasks, confirm,
+    /// cancel each, close pane) is in flight, so a rapid double-click can't race two runs.</summary>
+    [ObservableProperty] private bool _isAbandonPending;
+
     /// <summary>Raised when the terminal failed to start — the host surfaces this via the footer error strip.</summary>
     public event Action<string>? ErrorReported;
 
@@ -36,6 +46,12 @@ public sealed partial class ConPtyPaneViewModel : ViewModelBase, IDisposable
     /// commits the worktree and moves the task to WaitingForReview.</summary>
     public event Action<string>? SubmitForReviewRequested;
 
+    /// <summary>Raised when the user abandons a list-handler run (<see cref="IsListHandler"/>
+    /// only): the host looks up this round's still-open tasks, confirms with the user (naming the
+    /// count), cancels them, then closes this pane -- one action instead of closing the tile and
+    /// separately cancelling the queue.</summary>
+    public event Action<string>? AbandonRunRequested;
+
     /// <summary>Raised with <c>(taskId, exitCode)</c> when a task-based session that had been running
     /// dies non-zero. The host reports it to the worker, which decides whether this was a list
     /// handler killed by the usage limit and worth reopening. Ad-hoc panes never raise it — there is
@@ -141,6 +157,16 @@ public sealed partial class ConPtyPaneViewModel : ViewModelBase, IDisposable
 
     partial void OnIsSubmitPendingChanged(bool value) => SubmitForReviewCommand.NotifyCanExecuteChanged();
 
+    private bool CanAbandonRun() => IsListHandler && !IsAbandonPending;
+
+    [RelayCommand(CanExecute = nameof(CanAbandonRun))]
+    private void AbandonRun()
+    {
+        if (TaskId is { } id) AbandonRunRequested?.Invoke(id);
+    }
+
+    partial void OnIsAbandonPendingChanged(bool value) => AbandonRunCommand.NotifyCanExecuteChanged();
+
     // A launch failure permanently occupies the TaskId dedupe slot unless the user can retry —
     // re-opening the same task would otherwise just re-focus a dead tile.
     private bool CanRetry() => Terminal.HasExited && Terminal.StartError is not null;
diff --git a/src/ClaudeDo.Ui/ViewModels/MissionControlViewModel.cs b/src/ClaudeDo.Ui/ViewModels/MissionControlViewModel.cs
index 12f453e8..02d6f7ce 100644
--- a/src/ClaudeDo.Ui/ViewModels/MissionControlViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/MissionControlViewModel.cs
@@ -79,6 +79,10 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
     // MissionControlView.OnNewSessionClicked).
     public Action? BrowseForSessionRequested { get; set; }
 
+    // View-layer seam: confirms the "abandon run" action, naming the open-task count. Wired by the
+    // view the same way TasksIslandViewModel/DetailsIslandViewModel are.
+    public Func<string, System.Threading.Tasks.Task<bool>>? ConfirmAsync { get; set; }
+
     public UsagePillViewModel UsagePill { get; }
 
     public MissionControlViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory, IWorkerClient worker, UsagePillViewModel usagePill)
@@ -375,7 +379,7 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
             }
 
             AddConPtyPane(new ConPtyPaneViewModel(taskId, title,
-                () => DescribeAsync(() => launchSpec(taskId))));
+                () => DescribeAsync(() => launchSpec(taskId))) { IsListHandler = true });
         }
         finally
         {
@@ -416,7 +420,8 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
         catch { /* best-effort title lookup */ }
 
         AddConPtyPane(new ConPtyPaneViewModel(taskId, title,
-            () => DescribeAsync(() => _worker.GetMergeHelperHandoffLaunchSpecAsync(taskId, survivingTaskIds, nextPhase))));
+            () => DescribeAsync(() => _worker.GetMergeHelperHandoffLaunchSpecAsync(taskId, survivingTaskIds, nextPhase)))
+            { IsListHandler = true });
     }
 
     // The 5h usage window is about to run out under this handler session: type the worker's warning
@@ -440,6 +445,7 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
         pane.CloseRequested += CloseConPtySession;
         pane.SubmitForReviewRequested += OnPaneSubmitForReview;
         pane.SessionDiedAfterStartup += OnPaneSessionDied;
+        pane.AbandonRunRequested += OnPaneAbandonRun;
         ConPtySessions.Add(pane);
         pane.Start();
     }
@@ -495,6 +501,41 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
         }
     }
 
+    // Handler-run abort ("Not-Aus"): cancels every still-open (Queued/Running) task this handler
+    // round queued or started, then closes the pane -- one action instead of "close tile" + "cancel
+    // the tasks separately", which used to leave orphaned rows nobody merges. No open tasks (or no
+    // round entry at all -- 7-day retention, or a run predating this feature) closes the pane
+    // straight away, no confirmation needed. Guarded by IsAbandonPending like OnPaneSubmitForReview.
+    private async void OnPaneAbandonRun(string taskId)
+    {
+        if (ConPtySessions.FirstOrDefault(s => s.TaskId == taskId) is not { } pane || pane.IsAbandonPending)
+            return;
+
+        pane.IsAbandonPending = true;
+        try
+        {
+            var open = await _worker.GetHandlerOpenTasksAsync(taskId);
+            if (open.Count > 0)
+            {
+                if (ConfirmAsync is null) return;
+                if (!await ConfirmAsync(Loc.T("missionControl.abandonRunConfirm", open.Count))) return;
+
+                foreach (var task in open)
+                    await _worker.CancelTaskAsync(task.Id);
+            }
+
+            CloseConPtySession(pane);
+        }
+        catch (Exception ex)
+        {
+            ErrorReported?.Invoke(Loc.T("missionControl.abandonRunFailed", ex.Message));
+        }
+        finally
+        {
+            pane.IsAbandonPending = false;
+        }
+    }
+
     private void CloseConPtySession(ConPtyPaneViewModel pane)
     {
         if (!ConPtySessions.Contains(pane)) return;
@@ -502,6 +543,7 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
         pane.CloseRequested -= CloseConPtySession;
         pane.SubmitForReviewRequested -= OnPaneSubmitForReview;
         pane.SessionDiedAfterStartup -= OnPaneSessionDied;
+        pane.AbandonRunRequested -= OnPaneAbandonRun;
         ConPtySessions.Remove(pane);
         pane.Dispose();
     }
@@ -555,6 +597,7 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
             c.CloseRequested -= CloseConPtySession;
             c.SubmitForReviewRequested -= OnPaneSubmitForReview;
             c.SessionDiedAfterStartup -= OnPaneSessionDied;
+            c.AbandonRunRequested -= OnPaneAbandonRun;
             c.Dispose();
         }
         ConPtySessions.Clear();
diff --git a/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml b/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml
index 649f5d19..f6048afb 100644
--- a/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml
+++ b/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml
@@ -14,7 +14,7 @@
               Background="{DynamicResource Surface2Brush}"
               BorderBrush="{DynamicResource LineBrush}"
               BorderThickness="0,0,0,1" Padding="8,3">
-        <Grid ColumnDefinitions="*,Auto,Auto">
+        <Grid ColumnDefinitions="*,Auto,Auto,Auto">
           <TextBlock Grid.Column="0" Classes="meta" Text="{Binding DisplayTitle}"
                      TextTrimming="CharacterEllipsis"
                      ToolTip.Tip="{Binding DisplayTitle}"
@@ -25,7 +25,12 @@
                   Content="{loc:Tr missionControl.submitForReview}"
                   ToolTip.Tip="{loc:Tr missionControl.submitForReviewTip}"
                   Command="{Binding SubmitForReviewCommand}" />
-          <Button Grid.Column="2" Classes="title-ctrl"
+          <Button Grid.Column="2" Classes="btn" Margin="0,0,6,0"
+                  IsVisible="{Binding IsListHandler}"
+                  Content="{loc:Tr missionControl.abandonRun}"
+                  ToolTip.Tip="{loc:Tr missionControl.abandonRunTip}"
+                  Command="{Binding AbandonRunCommand}" />
+          <Button Grid.Column="3" Classes="title-ctrl"
                   Command="{Binding CloseCommand}"
                   ToolTip.Tip="{loc:Tr missionControl.closeSession}">
             <PathIcon Data="{StaticResource Icon.WinClose}" Width="12" Height="12"/>
diff --git a/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml.cs b/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml.cs
index 645cb7b1..5a59c6f3 100644
--- a/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml.cs
@@ -2,6 +2,7 @@ using System;
 using System.Collections.Specialized;
 using System.ComponentModel;
 using System.Linq;
+using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Layout;
 using Avalonia.Media;
@@ -55,6 +56,7 @@ public partial class MissionControlView : UserControl
             _vm.Panes.CollectionChanged -= OnPanesChanged;
             _vm.PropertyChanged -= OnViewModelPropertyChanged;
             _vm.BrowseForSessionRequested = null;
+            _vm.ConfirmAsync = null;
         }
 
         _vm = DataContext as MissionControlViewModel;
@@ -64,12 +66,59 @@ public partial class MissionControlView : UserControl
             _vm.Panes.CollectionChanged += OnPanesChanged;
             _vm.PropertyChanged += OnViewModelPropertyChanged;
             _vm.BrowseForSessionRequested = BrowseForSessionAsync;
+            _vm.ConfirmAsync = ShowConfirmAsync;
         }
 
         RebuildOverviewGrid();
         UpdateQueueColumn();
     }
 
+    // Abandon-run confirmation -- same TaskCompletionSource-backed plain Window as
+    // TasksIslandView.ShowConfirmAsync (no shared control for this shape yet).
+    private async Task<bool> ShowConfirmAsync(string message)
+    {
+        var owner = TopLevel.GetTopLevel(this) as Window;
+        if (owner is null) return false;
+
+        var tcs = new TaskCompletionSource<bool>();
+        var cancel = new Button { Content = "Cancel", MinWidth = 90 };
+        var confirm = new Button { Content = "Confirm", MinWidth = 90, Classes = { "danger" } };
+
+        var dialog = new Window
+        {
+            Title = "Confirm",
+            Width = 380,
+            SizeToContent = SizeToContent.Height,
+            CanResize = false,
+            WindowStartupLocation = WindowStartupLocation.CenterOwner,
+            ShowInTaskbar = false,
+            Background = this.FindResource("SurfaceBrush") as IBrush,
+            Content = new StackPanel
+            {
+                Margin = new Thickness(20),
+                Spacing = 16,
+                Children =
+                {
+                    new TextBlock { Text = message, TextWrapping = TextWrapping.Wrap },
+                    new StackPanel
+                    {
+                        Orientation = Orientation.Horizontal,
+                        HorizontalAlignment = HorizontalAlignment.Right,
+                        Spacing = 8,
+                        Children = { cancel, confirm },
+                    },
+                },
+            },
+        };
+
+        cancel.Click += (_, _) => { tcs.TrySetResult(false); dialog.Close(); };
+        confirm.Click += (_, _) => { tcs.TrySetResult(true); dialog.Close(); };
+        dialog.Closed += (_, _) => tcs.TrySetResult(false);
+
+        _ = dialog.ShowDialog(owner);
+        return await tcs.Task;
+    }
+
     private void OnPanesChanged(object? sender, NotifyCollectionChangedEventArgs e) => RebuildOverviewGrid();
 
     private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)
diff --git a/src/ClaudeDo.Worker/Hub/WorkerHub.cs b/src/ClaudeDo.Worker/Hub/WorkerHub.cs
index 02d44df5..92096817 100644
--- a/src/ClaudeDo.Worker/Hub/WorkerHub.cs
+++ b/src/ClaudeDo.Worker/Hub/WorkerHub.cs
@@ -73,6 +73,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
     private readonly TicketClientFactory _ticketClients;
     private readonly TicketImportService _ticketImport;
     private readonly HandlerRestartCoordinator? _handlerRestart;
+    private readonly HandlerRoundState? _roundState;
 
     public WorkerHub(
         QueueService queue,
@@ -112,7 +113,8 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         TicketPatStore ticketPat = null!,
         TicketClientFactory ticketClients = null!,
         TicketImportService ticketImport = null!,
-        HandlerRestartCoordinator? handlerRestart = null)
+        HandlerRestartCoordinator? handlerRestart = null,
+        HandlerRoundState? roundState = null)
     {
         _queue = queue;
         _waker = waker;
@@ -152,6 +154,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         _ticketClients = ticketClients;
         _ticketImport = ticketImport;
         _handlerRestart = handlerRestart;
+        _roundState = roundState;
     }
 
     // Persistence boundary for the session_skills JSON-array columns (task/list/global).
@@ -810,6 +813,24 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         _ = _handlerRestart.OnSessionExitedAsync(taskId, exitCode, CancellationToken.None);
     }
 
+    // The Mission Control "abandon run" action: what a handler round queued/started that is still
+    // open (Queued or Running), read from the structured HandlerRoundState store rather than
+    // parsed out of the handler task's description. Empty when there is no round entry (7-day
+    // retention, or a run from before this feature) or the round has no open tasks -- the caller
+    // treats both as "nothing to confirm, just close the pane".
+    public async Task<IReadOnlyList<HandlerOpenTaskDto>> GetHandlerOpenTasks(string handlerTaskId)
+    {
+        var round = _roundState?.Get(handlerTaskId);
+        if (round is not { TaskIds.Count: > 0 }) return Array.Empty<HandlerOpenTaskDto>();
+
+        await using var ctx = await _dbFactory.CreateDbContextAsync();
+        return await ctx.Tasks.AsNoTracking()
+            .Where(t => round.TaskIds.Contains(t.Id)
+                     && (t.Status == TaskStatus.Queued || t.Status == TaskStatus.Running))
+            .Select(t => new HandlerOpenTaskDto(t.Id, t.Title))
+            .ToListAsync();
+    }
+
     // Starts a planning session (worktree + prompt files + token, task -> Planning) and returns
     // the launch spec for an embedded ConPTY planning terminal -- the ConPTY replacement for
     // StartPlanningSessionAsync's external wt window. On any spec-build failure the just-started
diff --git a/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs b/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs
index 4478652d..7a219379 100644
--- a/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs
+++ b/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs
@@ -138,6 +138,8 @@ public abstract class StubWorkerClient : IWorkerClient
         => Task.FromResult(new LaunchSpec(".", "claude", Array.Empty<string>(), new Dictionary<string, string>()));
     public virtual Task ReportInteractiveSessionExitedAsync(string taskId, int exitCode, CancellationToken ct = default)
         => Task.CompletedTask;
+    public virtual Task<IReadOnlyList<HandlerOpenTaskDto>> GetHandlerOpenTasksAsync(string handlerTaskId, CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<HandlerOpenTaskDto>>(Array.Empty<HandlerOpenTaskDto>());
     public virtual Task<LaunchSpec> GetPlanningStartLaunchSpecAsync(string taskId, CancellationToken ct = default)
         => Task.FromResult(new LaunchSpec(".", "claude", Array.Empty<string>(), new Dictionary<string, string>()));
     public virtual Task<LaunchSpec> GetPlanningResumeLaunchSpecAsync(string taskId, CancellationToken ct = default)
diff --git a/tests/ClaudeDo.Ui.Tests/ViewModels/MissionControlViewModelTests.cs b/tests/ClaudeDo.Ui.Tests/ViewModels/MissionControlViewModelTests.cs
index c3d3f9b9..c75e2caa 100644
--- a/tests/ClaudeDo.Ui.Tests/ViewModels/MissionControlViewModelTests.cs
+++ b/tests/ClaudeDo.Ui.Tests/ViewModels/MissionControlViewModelTests.cs
@@ -966,4 +966,110 @@ public class MissionControlViewModelTests : IDisposable
         vm.ToggleLayoutCommand.Execute(null);
         Assert.False(vm.IsFocusMode);
     }
+
+    // ── Abandon run: single-action "stop session + cancel its still-open tasks" ────────────────
+
+    private sealed class RecordingAbandonWorker : StubWorkerClient
+    {
+        public IReadOnlyList<HandlerOpenTaskDto> OpenTasks { get; set; } = Array.Empty<HandlerOpenTaskDto>();
+        public readonly List<string> Cancelled = new();
+
+        public override Task<IReadOnlyList<HandlerOpenTaskDto>> GetHandlerOpenTasksAsync(string handlerTaskId, CancellationToken ct = default)
+            => Task.FromResult(OpenTasks);
+
+        public override Task CancelTaskAsync(string taskId)
+        {
+            Cancelled.Add(taskId);
+            return Task.CompletedTask;
+        }
+    }
+
+    // A plain OpenConPtySessionAsync pane (not a list handler) never shows/allows the action --
+    // acceptance criterion 5 ("only at handler panes").
+    [Fact]
+    public async Task AbandonRun_OnNonHandlerPane_IsNotAvailable()
+    {
+        var worker = new FakeWorker();
+        using var vm = BuildVm(worker);
+        await vm.OpenConPtySessionAsync("t1");
+        var pane = vm.ConPtySessions[0];
+
+        Assert.False(pane.IsListHandler);
+        Assert.False(pane.AbandonRunCommand.CanExecute(null));
+    }
+
+    [Fact]
+    public async Task AbandonRun_ListHandlerPane_IsListHandlerTrue_CommandAvailable()
+    {
+        var worker = new RecordingAbandonWorker();
+        using var vm = BuildVm(worker);
+        await vm.OpenMergeHelperConPtySessionAsync("L1", new[] { "t1" });
+        var pane = Assert.Single(vm.ConPtySessions);
+
+        Assert.True(pane.IsListHandler);
+        Assert.True(pane.AbandonRunCommand.CanExecute(null));
+    }
+
+    // Acceptance criterion 4: no open tasks (or no round entry, which the fake models the same
+    // way) closes the pane straight away -- no confirmation dialog.
+    [Fact]
+    public async Task AbandonRun_NoOpenTasks_ClosesPaneWithoutConfirming()
+    {
+        var worker = new RecordingAbandonWorker { OpenTasks = Array.Empty<HandlerOpenTaskDto>() };
+        using var vm = BuildVm(worker);
+        await vm.OpenMergeHelperConPtySessionAsync("L1", new[] { "t1" });
+        var pane = Assert.Single(vm.ConPtySessions);
+        var confirmCalled = false;
+        vm.ConfirmAsync = _ => { confirmCalled = true; return Task.FromResult(true); };
+
+        pane.AbandonRunCommand.Execute(null);
+        await Task.Delay(20);
+
+        Assert.False(confirmCalled);
+        Assert.Empty(vm.ConPtySessions);
+    }
+
+    // Acceptance criterion 3 (decline branch): declining leaves the session and its tasks
+    // untouched.
+    [Fact]
+    public async Task AbandonRun_OpenTasks_ConfirmDeclined_LeavesSessionAndTasksUntouched()
+    {
+        var worker = new RecordingAbandonWorker
+        {
+            OpenTasks = new[] { new HandlerOpenTaskDto("t1", "First"), new HandlerOpenTaskDto("t2", "Second") },
+        };
+        using var vm = BuildVm(worker);
+        await vm.OpenMergeHelperConPtySessionAsync("L1", new[] { "t1", "t2" });
+        var pane = Assert.Single(vm.ConPtySessions);
+        string? confirmMessage = null;
+        vm.ConfirmAsync = msg => { confirmMessage = msg; return Task.FromResult(false); };
+
+        pane.AbandonRunCommand.Execute(null);
+        await Task.Delay(20);
+
+        Assert.NotNull(confirmMessage);
+        Assert.Empty(worker.Cancelled);
+        Assert.Single(vm.ConPtySessions);
+    }
+
+    // Acceptance criteria 1-3 (accept branch): the count is confirmed, every open task is
+    // cancelled, then the pane closes -- one action instead of two.
+    [Fact]
+    public async Task AbandonRun_OpenTasks_ConfirmAccepted_CancelsEachThenClosesPane()
+    {
+        var worker = new RecordingAbandonWorker
+        {
+            OpenTasks = new[] { new HandlerOpenTaskDto("t1", "First"), new HandlerOpenTaskDto("t2", "Second") },
+        };
+        using var vm = BuildVm(worker);
+        await vm.OpenMergeHelperConPtySessionAsync("L1", new[] { "t1", "t2" });
+        var pane = Assert.Single(vm.ConPtySessions);
+        vm.ConfirmAsync = _ => Task.FromResult(true);
+
+        pane.AbandonRunCommand.Execute(null);
+        await Task.Delay(20);
+
+        Assert.Equal(new[] { "t1", "t2" }, worker.Cancelled);
+        Assert.Empty(vm.ConPtySessions);
+    }
 }
diff --git a/tests/ClaudeDo.Worker.Tests/Hub/HandlerOpenTasksHubTests.cs b/tests/ClaudeDo.Worker.Tests/Hub/HandlerOpenTasksHubTests.cs
new file mode 100644
index 00000000..cf6a9771
--- /dev/null
+++ b/tests/ClaudeDo.Worker.Tests/Hub/HandlerOpenTasksHubTests.cs
@@ -0,0 +1,141 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Git;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
+using ClaudeDo.Worker.Config;
+using ClaudeDo.Worker.Hub;
+using ClaudeDo.Worker.Lifecycle;
+using ClaudeDo.Worker.Runner;
+using ClaudeDo.Worker.Skills;
+using ClaudeDo.Worker.Tests.Infrastructure;
+using Xunit;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Worker.Tests.Hub;
+
+/// Covers WorkerHub.GetHandlerOpenTasks -- the Mission Control "abandon run" action's read side.
+/// The round's TaskIds come from HandlerRoundState (structured store, not the handler task's
+/// description); only rows still Queued or Running are returned, so WaitingForReview/Done/Failed/
+/// Cancelled/Idle work is never touched by a subsequent cancel loop.
+public sealed class HandlerOpenTasksHubTests : IDisposable
+{
+    private readonly DbFixture _db = new();
+    private readonly ClaudeDoDbContext _ctx;
+    private readonly TaskRepository _tasks;
+    private readonly ListRepository _lists;
+    private readonly string _roundsPath = Path.Combine(Path.GetTempPath(), $"claudedo_rounds_{Guid.NewGuid():N}.json");
+    private readonly HandlerRoundState _rounds;
+
+    private sealed class FakeSessionSkillRegistry : ISessionSkillRegistry
+    {
+        public Task<IReadOnlyList<string>> InstallAsync(string url, CancellationToken ct) => throw new NotImplementedException();
+        public Task UpdateAsync(string sourceUrl, CancellationToken ct) => throw new NotImplementedException();
+        public Task RemoveAsync(string sourceUrl, CancellationToken ct) => throw new NotImplementedException();
+        public Task<IReadOnlyList<SessionSkillEntity>> ListAsync(CancellationToken ct)
+            => Task.FromResult<IReadOnlyList<SessionSkillEntity>>(Array.Empty<SessionSkillEntity>());
+    }
+
+    public HandlerOpenTasksHubTests()
+    {
+        _ctx = _db.CreateContext();
+        _tasks = new TaskRepository(_ctx);
+        _lists = new ListRepository(_ctx);
+        _rounds = new HandlerRoundState(_roundsPath);
+    }
+
+    public void Dispose()
+    {
+        _ctx.Dispose();
+        _db.Dispose();
+        try { File.Delete(_roundsPath); } catch { /* best effort */ }
+    }
+
+    private WorkerHub CreateHub()
+    {
+        var factory = _db.CreateFactory();
+        var git = new GitService();
+        var wtManager = new WorktreeManager(git, factory, new WorkerConfig(), Microsoft.Extensions.Logging.Abstractions.NullLogger<WorktreeManager>.Instance);
+        var interactiveLaunchSpec = new InteractiveLaunchSpecService(
+            factory, new FakeSessionSkillSeeder(), new FakeSessionSkillRegistry(), wtManager, git,
+            new WorkerConfig { ClaudeBin = "claude" }, new ClaudeDo.Worker.External.HandoffRoundTracker(), _rounds);
+        var built = TaskStateServiceBuilder.Build(factory);
+
+        var hub = new WorkerHub(
+            null!, null!, null!, null!, null!, factory, null!, null!, null!,
+            null!, null!, null!, null!, null!, null!, null!, built.State, null!, null!,
+            null!, new ClaudeDo.Worker.Online.OnlineInboxConfig(), new ClaudeDo.Worker.OnlineRefreshTokenStore(new ClaudeDo.Worker.DpapiTokenStore("unused.token")),
+            new ClaudeDo.Worker.Runner.PendingQuestionRegistry(), null!,
+            logBuffer: null, interactiveLaunchSpec: interactiveLaunchSpec, worktreeManager: wtManager, git: git,
+            roundState: _rounds);
+        return hub;
+    }
+
+    private async Task<string> SeedListAsync(string name = "L")
+    {
+        var listId = Guid.NewGuid().ToString();
+        await _lists.AddAsync(new ListEntity { Id = listId, Name = name, WorkingDir = Path.GetTempPath(), CreatedAt = DateTime.UtcNow });
+        return listId;
+    }
+
+    private async Task<TaskEntity> SeedTaskAsync(string listId, TaskStatus status, string title = "T")
+    {
+        var task = new TaskEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            ListId = listId,
+            Title = title,
+            Status = status,
+            CreatedAt = DateTime.UtcNow,
+        };
+        await _tasks.AddAsync(task);
+        return task;
+    }
+
+    [Fact]
+    public async Task NoRoundEntry_ReturnsEmpty()
+    {
+        var hub = CreateHub();
+        var result = await hub.GetHandlerOpenTasks("no-such-handler-task");
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public async Task RoundWithOnlyTerminalTasks_ReturnsEmpty()
+    {
+        var listId = await SeedListAsync();
+        var done = await SeedTaskAsync(listId, TaskStatus.Done, "Done task");
+        var review = await SeedTaskAsync(listId, TaskStatus.WaitingForReview, "Review task");
+        var failed = await SeedTaskAsync(listId, TaskStatus.Failed, "Failed task");
+        var cancelled = await SeedTaskAsync(listId, TaskStatus.Cancelled, "Cancelled task");
+        var idle = await SeedTaskAsync(listId, TaskStatus.Idle, "Idle task");
+        var handlerTaskId = "handler-1";
+        _rounds.Save(new HandlerRound(handlerTaskId, "wait",
+            new[] { done.Id, review.Id, failed.Id, cancelled.Id, idle.Id }, DateTime.UtcNow));
+
+        var hub = CreateHub();
+        var result = await hub.GetHandlerOpenTasks(handlerTaskId);
+
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public async Task RoundWithMixedTasks_ReturnsOnlyQueuedAndRunning()
+    {
+        var listId = await SeedListAsync();
+        var queued = await SeedTaskAsync(listId, TaskStatus.Queued, "Queued task");
+        var running = await SeedTaskAsync(listId, TaskStatus.Running, "Running task");
+        var done = await SeedTaskAsync(listId, TaskStatus.Done, "Done task");
+        var notInRound = await SeedTaskAsync(listId, TaskStatus.Queued, "Unrelated queued task");
+        var handlerTaskId = "handler-2";
+        _rounds.Save(new HandlerRound(handlerTaskId, "wait",
+            new[] { queued.Id, running.Id, done.Id }, DateTime.UtcNow));
+
+        var hub = CreateHub();
+        var result = await hub.GetHandlerOpenTasks(handlerTaskId);
+
+        Assert.Equal(2, result.Count);
+        Assert.Contains(result, r => r.Id == queued.Id && r.Title == "Queued task");
+        Assert.Contains(result, r => r.Id == running.Id && r.Title == "Running task");
+        Assert.DoesNotContain(result, r => r.Id == notInRound.Id);
+    }
+}