diff --git a/src/ClaudeDo.Localization/locales/de.json b/src/ClaudeDo.Localization/locales/de.json
index eb13706..8a23529 100644
--- a/src/ClaudeDo.Localization/locales/de.json
+++ b/src/ClaudeDo.Localization/locales/de.json
@@ -66,7 +66,6 @@
     "addPlaceholder": "Aufgabe hinzufügen…",
     "enterKey": "ENTER",
     "notesPinnedRow": "Notizen (Tagesnotizen)",
-    "prepareDay": "Tag vorbereiten",
     "clearDayTip": "Tag leeren",
     "prepLogTip": "Vorbereitungs-Log",
     "overdue": "ÜBERFÄLLIG",
@@ -140,7 +139,9 @@
     "previewBtn": "Vorschau",
     "editBtn": "Bearbeiten",
     "descriptionPlaceholder": "Aufgabendetails hinzufügen (Markdown unterstützt)...",
-    "prepTitle": "Tagesvorbereitung"
+    "prepTitle": "Tagesvorbereitung",
+    "planDay": "Tag planen",
+    "prepEmpty": "Heute noch keine Vorbereitung — klick Tag planen"
   },
   "agent": {
     "stopTip": "Agent stoppen",
diff --git a/src/ClaudeDo.Localization/locales/en.json b/src/ClaudeDo.Localization/locales/en.json
index b4ee915..e25721b 100644
--- a/src/ClaudeDo.Localization/locales/en.json
+++ b/src/ClaudeDo.Localization/locales/en.json
@@ -66,7 +66,6 @@
     "addPlaceholder": "Add a task…",
     "enterKey": "ENTER",
     "notesPinnedRow": "Notes (daily notes)",
-    "prepareDay": "Prepare day",
     "clearDayTip": "Clear day",
     "prepLogTip": "Prep log",
     "overdue": "OVERDUE",
@@ -140,7 +139,9 @@
     "previewBtn": "Preview",
     "editBtn": "Edit",
     "descriptionPlaceholder": "Add task details (markdown supported)...",
-    "prepTitle": "Daily prep"
+    "prepTitle": "Daily prep",
+    "planDay": "Plan day",
+    "prepEmpty": "No prep run today yet — click Plan day"
   },
   "agent": {
     "stopTip": "Stop agent",
diff --git a/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs b/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs
index 5360151..e4335d1 100644
--- a/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs
@@ -346,6 +346,8 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
             RecomputeCanMergeAll();
             ReviewCombinedDiffCommand.NotifyCanExecuteChanged();
         };
+
+        PrepLog.CollectionChanged += (_, _) => OnPropertyChanged(nameof(ShowPrepEmptyState));
     }
 
     private void OnTaskMessage(string taskId, string line)
@@ -381,6 +383,18 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
         AppendClaudeText(formatted, target, buf);
     }
 
+    [RelayCommand]
+    private async Task PlanDayAsync()
+    {
+        if (_worker is null) return;
+        try { await _worker.RunDailyPrepNowAsync(); }
+        catch { /* worker offline; PrepStarted/PrepLine will reconcile */ }
+    }
+
+    public bool ShowPrepEmptyState => !IsPrepRunning && PrepLog.Count == 0;
+
+    partial void OnIsPrepRunningChanged(bool value) => OnPropertyChanged(nameof(ShowPrepEmptyState));
+
     private void OnPrepStarted()
     {
         PrepLog.Clear();
diff --git a/src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs b/src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs
index 31e86da..0875488 100644
--- a/src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs
@@ -37,15 +37,6 @@ public sealed partial class TasksIslandViewModel : ViewModelBase
         NotesRequested?.Invoke();
     }
 
-    [RelayCommand]
-    private async Task PrepareDayAsync()
-    {
-        if (_worker is null) return;
-        PrepRequested?.Invoke();
-        try { await _worker.RunDailyPrepNowAsync(); }
-        catch { /* worker offline; broadcast will reconcile on return */ }
-    }
-
     [RelayCommand]
     private void ShowPrepLog() => PrepRequested?.Invoke();
 
diff --git a/src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml b/src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml
index d17c4e2..1a92704 100644
--- a/src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml
+++ b/src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml
@@ -303,9 +303,23 @@
       <islands:NotesEditorView DataContext="{Binding Notes}"/>
     </Panel>
     <Panel IsVisible="{Binding IsPrepMode}">
-      <islands:SessionTerminalView
-          Entries="{Binding PrepLog}" Label="daily-prep"
-          IsRunning="{Binding IsPrepRunning}"/>
+      <DockPanel>
+        <Border DockPanel.Dock="Top" Padding="12,8">
+          <Button Classes="btn primary"
+                  Command="{Binding PlanDayCommand}"
+                  IsEnabled="{Binding !IsPrepRunning}"
+                  Content="{loc:Tr details.planDay}"/>
+        </Border>
+        <Panel>
+          <islands:SessionTerminalView
+              Entries="{Binding PrepLog}" Label="daily-prep"
+              IsRunning="{Binding IsPrepRunning}"/>
+          <TextBlock IsVisible="{Binding ShowPrepEmptyState}"
+                     HorizontalAlignment="Center" VerticalAlignment="Center"
+                     Foreground="{DynamicResource TextMuteBrush}"
+                     Text="{loc:Tr details.prepEmpty}"/>
+        </Panel>
+      </DockPanel>
     </Panel>
     </Grid>
 
diff --git a/src/ClaudeDo.Ui/Views/Islands/TasksIslandView.axaml b/src/ClaudeDo.Ui/Views/Islands/TasksIslandView.axaml
index ff48fb8..2470c47 100644
--- a/src/ClaudeDo.Ui/Views/Islands/TasksIslandView.axaml
+++ b/src/ClaudeDo.Ui/Views/Islands/TasksIslandView.axaml
@@ -79,14 +79,6 @@
             Command="{Binding OpenNotesCommand}"
             Content="{loc:Tr tasks.notesPinnedRow}"/>
 
-    <!-- Prepare Day button (My Day only) -->
-    <Button DockPanel.Dock="Top"
-            Classes="btn" HorizontalAlignment="Stretch" HorizontalContentAlignment="Left"
-            Margin="16,0,16,8"
-            IsVisible="{Binding IsMyDayList}"
-            Command="{Binding PrepareDayCommand}"
-            Content="{loc:Tr tasks.prepareDay}"/>
-
     <!-- Task list -->
     <ScrollViewer>
       <StackPanel Margin="10,4">
diff --git a/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs b/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs
index 47384cb..6231ee0 100644
--- a/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs
+++ b/tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs
@@ -33,6 +33,7 @@ public abstract class StubWorkerClient : IWorkerClient
 #pragma warning restore CS0067
 
     public int ClearMyDayCalls { get; private set; }
+    public int RunDailyPrepNowCalls { get; private set; }
 
     public void RaisePrepStarted() => PrepStartedEvent?.Invoke();
     public void RaisePrepLine(string line) => PrepLineEvent?.Invoke(line);
@@ -71,7 +72,7 @@ public abstract class StubWorkerClient : IWorkerClient
     public virtual Task QueuePlanningSubtasksAsync(string parentTaskId, CancellationToken ct = default) => Task.CompletedTask;
     public virtual Task<string?> GetWeekReportAsync(DateOnly start, DateOnly end) => Task.FromResult<string?>(null);
     public virtual Task<string> GenerateWeekReportAsync(DateOnly start, DateOnly end) => Task.FromResult("");
-    public virtual Task<bool> RunDailyPrepNowAsync() => Task.FromResult(false);
+    public virtual Task<bool> RunDailyPrepNowAsync() { RunDailyPrepNowCalls++; return Task.FromResult(false); }
     public virtual Task ClearMyDayAsync() { ClearMyDayCalls++; return Task.CompletedTask; }
     public virtual Task<AppSettingsDto?> GetAppSettingsAsync() => Task.FromResult<AppSettingsDto?>(null);
     public virtual Task<List<DailyNoteDto>> GetDailyNotesAsync(DateOnly day) => Task.FromResult(new List<DailyNoteDto>());
diff --git a/tests/ClaudeDo.Ui.Tests/ViewModels/DetailsIslandPrepModeTests.cs b/tests/ClaudeDo.Ui.Tests/ViewModels/DetailsIslandPrepModeTests.cs
index 19e15cf..487ae1d 100644
--- a/tests/ClaudeDo.Ui.Tests/ViewModels/DetailsIslandPrepModeTests.cs
+++ b/tests/ClaudeDo.Ui.Tests/ViewModels/DetailsIslandPrepModeTests.cs
@@ -92,4 +92,20 @@ public class DetailsIslandPrepModeTests : IDisposable
 
         Assert.NotEmpty(vm.PrepLog);
     }
+
+    [Fact]
+    public async Task PlanDayCommand_calls_worker()
+    {
+        var stub = new DefaultStub();
+        var vm = NewDetailsVm(stub);
+        await vm.PlanDayCommand.ExecuteAsync(null);
+        Assert.Equal(1, stub.RunDailyPrepNowCalls);
+    }
+
+    [Fact]
+    public void ShowPrepEmptyState_true_when_empty_and_not_running()
+    {
+        var vm = NewDetailsVm(new DefaultStub());
+        Assert.True(vm.ShowPrepEmptyState);
+    }
 }
diff --git a/tests/ClaudeDo.Ui.Tests/ViewModels/TasksIslandDailyPrepTests.cs b/tests/ClaudeDo.Ui.Tests/ViewModels/TasksIslandDailyPrepTests.cs
index f212be6..b7edb17 100644
--- a/tests/ClaudeDo.Ui.Tests/ViewModels/TasksIslandDailyPrepTests.cs
+++ b/tests/ClaudeDo.Ui.Tests/ViewModels/TasksIslandDailyPrepTests.cs
@@ -53,15 +53,4 @@ public class TasksIslandDailyPrepTests : IDisposable
         Assert.Equal(1, stub.ClearMyDayCalls);
     }
 
-    [Fact]
-    public async Task PrepareDayCommand_raises_PrepRequested()
-    {
-        var vm = NewTasksVm(new DefaultStub());
-        var raised = false;
-        vm.PrepRequested += () => raised = true;
-
-        await vm.PrepareDayCommand.ExecuteAsync(null);
-
-        Assert.True(raised);
-    }
 }