구조 개선: transcript 지연 가상화와 tool executor 분리 적용

이번 변경은 claude-code 기준 구조 강건성을 높이기 위한 리팩터링입니다.

핵심 수정 사항:

- AX Agent transcript를 TranscriptVisualItem/TranscriptVisualHost 기반 지연 materialization 구조로 전환해 MessageList 가상화 기반을 강화했습니다.

- StreamingToolExecutionCoordinator를 IToolExecutionCoordinator 뒤로 분리해 AgentLoopService가 구체 구현에 직접 묶이지 않도록 정리했습니다.

- 라이브 진행 카드 렌더를 ChatWindow.LiveProgressPresentation partial로 이동해 ChatWindow.xaml.cs의 책임을 더 줄였습니다.

- 기존 메시지 bubble 조립 로직을 유지하면서 transcript host가 필요 시점에 bubble을 만들 수 있도록 helper 경로를 추가했습니다.

검증 결과:

- dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\

- 경고 0 / 오류 0

src/AxCopilot/Views/ChatWindow.LiveProgressPresentation.cs

@@ -0,0 +1,208 @@
+using System;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Media;
+using System.Windows.Media.Animation;
+using System.Windows.Threading;
+
+namespace AxCopilot.Views;
+
+public partial class ChatWindow
+{
+    private void ShowAgentLiveCard(string runTab)
+    {
+        if (MessageList == null) return;
+        if (!string.Equals(runTab, _activeTab, StringComparison.OrdinalIgnoreCase)) return;
+
+        RemoveAgentLiveCard(animated: false);
+
+        _agentLiveStartTime = DateTime.UtcNow;
+        _agentLiveSubItemTexts.Clear();
+        _agentLiveCurrentCategory = null;
+
+        var msgMaxWidth = GetMessageMaxWidth();
+        var secondaryText = TryFindResource("SecondaryText") as Brush ?? Brushes.Gray;
+        var borderBrush = TryFindResource("BorderColor") as Brush ?? Brushes.Gray;
+
+        var container = new StackPanel
+        {
+            HorizontalAlignment = HorizontalAlignment.Center,
+            Width = msgMaxWidth,
+            MaxWidth = msgMaxWidth,
+            Margin = new Thickness(0, 4, 0, 6),
+            Opacity = IsLightweightLiveProgressMode(runTab) ? 1 : 0,
+            RenderTransform = IsLightweightLiveProgressMode(runTab)
+                ? Transform.Identity
+                : new TranslateTransform(0, 8),
+        };
+        if (!IsLightweightLiveProgressMode(runTab))
+        {
+            container.BeginAnimation(UIElement.OpacityProperty,
+                new DoubleAnimation(0, 1, TimeSpan.FromMilliseconds(260)));
+            ((TranslateTransform)container.RenderTransform).BeginAnimation(
+                TranslateTransform.YProperty,
+                new DoubleAnimation(8, 0, TimeSpan.FromMilliseconds(280))
+                {
+                    EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseOut }
+                });
+        }
+
+        var headerGrid = new Grid { Margin = new Thickness(2, 0, 0, 3) };
+        headerGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
+        headerGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
+        headerGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
+
+        var liveIcon = CreateMiniLauncherIcon(pixelSize: 4.0);
+        if (!IsLightweightLiveProgressMode(runTab))
+        {
+            liveIcon.BeginAnimation(
+                UIElement.OpacityProperty,
+                new DoubleAnimation(1.0, 0.35, TimeSpan.FromMilliseconds(750))
+                {
+                    AutoReverse = true,
+                    RepeatBehavior = RepeatBehavior.Forever,
+                    EasingFunction = new SineEase()
+                });
+        }
+
+        Grid.SetColumn(liveIcon, 0);
+        headerGrid.Children.Add(liveIcon);
+
+        var (agentName, _, _) = GetAgentIdentity();
+        var nameTb = new TextBlock
+        {
+            Text = agentName,
+            FontSize = 11,
+            FontWeight = FontWeights.SemiBold,
+            Foreground = secondaryText,
+            Margin = new Thickness(6, 0, 0, 0),
+            VerticalAlignment = VerticalAlignment.Center,
+        };
+        Grid.SetColumn(nameTb, 1);
+        headerGrid.Children.Add(nameTb);
+
+        _agentLiveElapsedText = new TextBlock
+        {
+            Text = "",
+            FontSize = 10,
+            Foreground = secondaryText,
+            Opacity = 0.50,
+            HorizontalAlignment = HorizontalAlignment.Right,
+            VerticalAlignment = VerticalAlignment.Center,
+        };
+        Grid.SetColumn(_agentLiveElapsedText, 2);
+        headerGrid.Children.Add(_agentLiveElapsedText);
+        container.Children.Add(headerGrid);
+
+        var card = new Border
+        {
+            BorderBrush = borderBrush,
+            BorderThickness = new Thickness(1),
+            CornerRadius = new CornerRadius(12),
+            Padding = new Thickness(13, 10, 13, 10),
+        };
+        card.SetResourceReference(Border.BackgroundProperty, "ItemBackground");
+
+        var cardStack = new StackPanel();
+        _agentLiveStatusText = new TextBlock
+        {
+            Text = "준비 중...",
+            FontSize = 12,
+            FontFamily = new FontFamily("Segoe UI, Malgun Gothic"),
+            Foreground = secondaryText,
+            TextWrapping = TextWrapping.Wrap,
+        };
+        cardStack.Children.Add(_agentLiveStatusText);
+
+        _agentLiveSubItems = new StackPanel { Margin = new Thickness(0, 6, 0, 0) };
+        cardStack.Children.Add(_agentLiveSubItems);
+
+        card.Child = cardStack;
+        container.Children.Add(card);
+
+        _agentLiveContainer = container;
+        AddTranscriptElement(container);
+        ForceScrollToEnd();
+
+        _agentLiveElapsedTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
+        _agentLiveElapsedTimer.Tick += (_, _) =>
+        {
+            if (_agentLiveElapsedText == null)
+                return;
+
+            var sec = (int)(DateTime.UtcNow - _agentLiveStartTime).TotalSeconds;
+            _agentLiveElapsedText.Text = sec > 0 ? $"{sec}초 경과" : "";
+        };
+        _agentLiveElapsedTimer.Start();
+    }
+
+    private void UpdateAgentLiveCard(string message, string? subItem = null,
+        string? category = null, bool clearSubItems = false)
+    {
+        if (_agentLiveContainer == null || _agentLiveStatusText == null) return;
+
+        _agentLiveStatusText.Text = message;
+
+        if (clearSubItems || (category != null && category != _agentLiveCurrentCategory))
+        {
+            _agentLiveSubItemTexts.Clear();
+            _agentLiveSubItems?.Children.Clear();
+            if (category != null)
+                _agentLiveCurrentCategory = category;
+        }
+
+        if (string.IsNullOrEmpty(subItem) || _agentLiveSubItemTexts.Contains(subItem))
+            return;
+
+        _agentLiveSubItemTexts.Add(subItem);
+        const int maxLiveSubItems = 8;
+        if (_agentLiveSubItemTexts.Count > maxLiveSubItems)
+        {
+            _agentLiveSubItemTexts.RemoveAt(0);
+            if (_agentLiveSubItems?.Children.Count > 0)
+                _agentLiveSubItems.Children.RemoveAt(0);
+        }
+
+        var secondary = TryFindResource("SecondaryText") as Brush ?? Brushes.Gray;
+        var tb = new TextBlock
+        {
+            Text = $"› {subItem}",
+            FontSize = 10.5,
+            FontFamily = new FontFamily("Segoe UI, Malgun Gothic"),
+            Foreground = secondary,
+            Opacity = 0.62,
+            TextTrimming = TextTrimming.CharacterEllipsis,
+            MaxWidth = 520,
+            Margin = new Thickness(0, 1, 0, 0),
+        };
+        _agentLiveSubItems?.Children.Add(tb);
+        ForceScrollToEnd();
+    }
+
+    private void RemoveAgentLiveCard(bool animated = true)
+    {
+        _agentLiveElapsedTimer?.Stop();
+        _agentLiveElapsedTimer = null;
+
+        if (_agentLiveContainer == null)
+            return;
+
+        var toRemove = _agentLiveContainer;
+        _agentLiveContainer = null;
+        _agentLiveStatusText = null;
+        _agentLiveSubItems = null;
+        _agentLiveElapsedText = null;
+        _agentLiveSubItemTexts.Clear();
+        _agentLiveCurrentCategory = null;
+
+        if (animated && ContainsTranscriptElement(toRemove) && !IsLightweightLiveProgressMode())
+        {
+            var anim = new DoubleAnimation(toRemove.Opacity, 0, TimeSpan.FromMilliseconds(160));
+            anim.Completed += (_, _) => RemoveTranscriptElement(toRemove);
+            toRemove.BeginAnimation(UIElement.OpacityProperty, anim);
+            return;
+        }
+
+        RemoveTranscriptElement(toRemove);
+    }
+}

src/AxCopilot/Views/ChatWindow.MessageBubblePresentation.cs

@@ -10,6 +10,16 @@ namespace AxCopilot.Views;
 
 public partial class ChatWindow
 {
+    private UIElement CreateMessageBubbleElement(string role, string content, bool animate = true, ChatMessage? message = null)
+    {
+        var beforeCount = GetTranscriptElementCount();
+        AddMessageBubble(role, content, animate, message);
+        var element = GetTranscriptElementAt(beforeCount)
+                      ?? throw new InvalidOperationException("메시지 버블을 생성하지 못했습니다.");
+        RemoveTranscriptElementAt(beforeCount);
+        return element;
+    }
+
     private void AddMessageBubble(string role, string content, bool animate = true, ChatMessage? message = null)
     {
         var isUser = role == "user";

src/AxCopilot/Views/ChatWindow.TimelinePresentation.cs

@@ -116,11 +116,21 @@ public partial class ChatWindow
             var cacheKey = $"m_{msg.MsgId}";
             timeline.Add((cacheKey, msg.Timestamp, 0, () =>
             {
-                // 캐시된 버블이 있으면 재생성 없이 재사용 (O(1) Add vs 전체 재생성)
-                if (_elementCache.TryGetValue(cacheKey, out var cached))
-                    AddTranscriptElement(cached);
-                else
-                    AddMessageBubble(capturedMsg.Role, capturedMsg.Content, animate: false, message: capturedMsg);
+                AddDeferredTranscriptElement(
+                    cacheKey,
+                    () =>
+                    {
+                        if (_elementCache.TryGetValue(cacheKey, out var cached))
+                            return cached;
+
+                        var element = CreateMessageBubbleElement(
+                            capturedMsg.Role,
+                            capturedMsg.Content,
+                            animate: false,
+                            message: capturedMsg);
+                        _elementCache[cacheKey] = element;
+                        return element;
+                    });
             }));
         }
 

src/AxCopilot/Views/ChatWindow.TranscriptHost.cs

@@ -1,3 +1,5 @@
+using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Windows;
 using System.Windows.Controls;
@@ -7,7 +9,8 @@ namespace AxCopilot.Views;
 
 public partial class ChatWindow
 {
-    private readonly ObservableCollection<UIElement> _transcriptElements = [];
+    private readonly ObservableCollection<TranscriptVisualItem> _transcriptElements = [];
+    private readonly Dictionary<UIElement, TranscriptVisualItem> _transcriptElementMap = new();
     private ScrollViewer? _transcriptScrollViewer;
     private bool _transcriptScrollHooked;
 
@@ -55,6 +58,8 @@ public partial class ChatWindow
         return null;
     }
 
+    private static string CreateTranscriptElementKey() => $"ui_{Guid.NewGuid():N}";
+
     private int GetTranscriptElementCount() => _transcriptElements.Count;
 
     private UIElement? GetTranscriptElementAt(int index)
@@ -62,24 +67,73 @@ public partial class ChatWindow
         if (index < 0 || index >= _transcriptElements.Count)
             return null;
 
-        return _transcriptElements[index];
+        return _transcriptElements[index].GetOrCreateElement();
     }
 
-    private int GetTranscriptElementIndex(UIElement element) => _transcriptElements.IndexOf(element);
+    private int GetTranscriptElementIndex(UIElement element)
+    {
+        if (_transcriptElementMap.TryGetValue(element, out var item))
+            return _transcriptElements.IndexOf(item);
 
-    private bool ContainsTranscriptElement(UIElement element) => _transcriptElements.Contains(element);
+        for (var i = 0; i < _transcriptElements.Count; i++)
+        {
+            var candidate = _transcriptElements[i];
+            if (!candidate.IsMaterialized)
+                continue;
 
-    private void AddTranscriptElement(UIElement element) => _transcriptElements.Add(element);
+            if (ReferenceEquals(candidate.Element, element))
+            {
+                _transcriptElementMap[element] = candidate;
+                return i;
+            }
+        }
 
-    private void ClearTranscriptElements() => _transcriptElements.Clear();
+        return -1;
+    }
 
-    private void RemoveTranscriptElement(UIElement element) => _transcriptElements.Remove(element);
+    private bool ContainsTranscriptElement(UIElement element) => GetTranscriptElementIndex(element) >= 0;
+
+    private TranscriptVisualItem WrapTranscriptElement(string key, UIElement element)
+    {
+        var item = new TranscriptVisualItem(key, element);
+        _transcriptElementMap[element] = item;
+        return item;
+    }
+
+    private void AddTranscriptElement(UIElement element)
+        => _transcriptElements.Add(WrapTranscriptElement(CreateTranscriptElementKey(), element));
+
+    private void AddDeferredTranscriptElement(string key, Func<UIElement> elementFactory)
+    {
+        TranscriptVisualItem? item = null;
+        item = new TranscriptVisualItem(
+            key,
+            elementFactory,
+            element => _transcriptElementMap[element] = item!);
+        _transcriptElements.Add(item);
+    }
+
+    private void ClearTranscriptElements()
+    {
+        _transcriptElements.Clear();
+        _transcriptElementMap.Clear();
+    }
+
+    private void RemoveTranscriptElement(UIElement element)
+    {
+        var index = GetTranscriptElementIndex(element);
+        if (index >= 0)
+            RemoveTranscriptElementAt(index);
+    }
 
     private void RemoveTranscriptElementAt(int index)
     {
         if (index < 0 || index >= _transcriptElements.Count)
             return;
 
+        var item = _transcriptElements[index];
+        if (item.Element != null)
+            _transcriptElementMap.Remove(item.Element);
         _transcriptElements.RemoveAt(index);
     }
 
@@ -88,7 +142,11 @@ public partial class ChatWindow
         if (index < 0 || index >= _transcriptElements.Count)
             return;
 
-        _transcriptElements[index] = element;
+        var previous = _transcriptElements[index];
+        if (previous.Element != null)
+            _transcriptElementMap.Remove(previous.Element);
+
+        _transcriptElements[index] = WrapTranscriptElement(CreateTranscriptElementKey(), element);
     }
 
     private double GetTranscriptScrollableHeight() => _transcriptScrollViewer?.ScrollableHeight ?? 0;

src/AxCopilot/Views/ChatWindow.xaml

@@ -2,6 +2,7 @@
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:wv2="clr-namespace:Microsoft.Web.WebView2.Wpf;assembly=Microsoft.Web.WebView2.Wpf"
+        xmlns:local="clr-namespace:AxCopilot.Views"
         Title="AX Copilot — AX Agent"
         Width="1180" Height="880"
         MinWidth="780" MinHeight="560"
@@ -1378,6 +1379,11 @@
                             <VirtualizingStackPanel/>
                         </ItemsPanelTemplate>
                     </ListBox.ItemsPanel>
+                    <ListBox.ItemTemplate>
+                        <DataTemplate DataType="{x:Type local:TranscriptVisualItem}">
+                            <local:TranscriptVisualHost/>
+                        </DataTemplate>
+                    </ListBox.ItemTemplate>
                     <ListBox.ItemContainerStyle>
                         <Style TargetType="ListBoxItem">
                             <Setter Property="Focusable" Value="False"/>

src/AxCopilot/Views/ChatWindow.xaml.cs

@@ -3530,6 +3530,7 @@ public partial class ChatWindow : Window
 
     private void ShowDropActionMenu(string[] files)
     {
+        if (files == null || files.Length == 0) return;
         // 파일 유형 판별
         var ext = System.IO.Path.GetExtension(files[0]).ToLowerInvariant();
         string category;
@@ -4243,7 +4244,9 @@ public partial class ChatWindow : Window
         if (string.IsNullOrWhiteSpace(raw) || string.Equals(raw, command, StringComparison.OrdinalIgnoreCase))
             return ("open", "");
         var parts = raw.Split(' ', StringSplitOptions.RemoveEmptyEntries);
-        if (parts.Length <= 1)
+        if (parts.Length == 0)
+            return ("open", "");
+        if (parts.Length == 1)
             return (parts[0].Trim().ToLowerInvariant(), "");
         return (parts[0].Trim().ToLowerInvariant(), string.Join(' ', parts.Skip(1)).Trim());
     }
@@ -5515,7 +5518,8 @@ public partial class ChatWindow : Window
     }
 
     private AgentLoopService GetAgentLoop(string tab) =>
-        _agentLoops.TryGetValue(tab, out var loop) ? loop : _agentLoops.Values.First();
+        _agentLoops.TryGetValue(tab, out var loop) ? loop : _agentLoops.Values.FirstOrDefault()
+            ?? throw new InvalidOperationException($"No agent loop registered for tab '{tab}'");
 
     private async Task<string> RunAgentLoopAsync(
         string runTab,
@@ -6840,200 +6844,6 @@ public partial class ChatWindow : Window
 
     // ─── 채팅창 내 에이전트 라이브 진행 카드 ─────────────────────────────────────
 
-    private void ShowAgentLiveCard(string runTab)
-    {
-        if (MessageList == null) return;
-        if (!string.Equals(runTab, _activeTab, StringComparison.OrdinalIgnoreCase)) return;
-
-        RemoveAgentLiveCard(animated: false); // 기존 카드 즉시 제거
-
-        _agentLiveStartTime = DateTime.UtcNow;
-        _agentLiveSubItemTexts.Clear();
-        _agentLiveCurrentCategory = null;
-
-        var msgMaxWidth = GetMessageMaxWidth();
-        var secondaryText = TryFindResource("SecondaryText") as Brush ?? Brushes.Gray;
-        var borderBrush = TryFindResource("BorderColor") as Brush ?? Brushes.Gray;
-        var accentBrush = TryFindResource("AccentColor") as Brush ?? Brushes.CornflowerBlue;
-
-        var container = new StackPanel
-        {
-            HorizontalAlignment = HorizontalAlignment.Center,
-            Width = msgMaxWidth,
-            MaxWidth = msgMaxWidth,
-            Margin = new Thickness(0, 4, 0, 6),
-            Opacity = IsLightweightLiveProgressMode(runTab) ? 1 : 0,
-            RenderTransform = IsLightweightLiveProgressMode(runTab)
-                ? Transform.Identity
-                : new TranslateTransform(0, 8),
-        };
-        if (!IsLightweightLiveProgressMode(runTab))
-        {
-            container.BeginAnimation(UIElement.OpacityProperty,
-                new DoubleAnimation(0, 1, TimeSpan.FromMilliseconds(260)));
-            ((TranslateTransform)container.RenderTransform).BeginAnimation(
-                TranslateTransform.YProperty,
-                new DoubleAnimation(8, 0, TimeSpan.FromMilliseconds(280))
-                { EasingFunction = new System.Windows.Media.Animation.QuadraticEase
-                    { EasingMode = System.Windows.Media.Animation.EasingMode.EaseOut } });
-        }
-
-        // 헤더: 펄싱 아이콘 + 에이전트 이름 + 경과 시간
-        var headerGrid = new Grid { Margin = new Thickness(2, 0, 0, 3) };
-        headerGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
-        headerGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
-        headerGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
-
-        var liveIcon = CreateMiniLauncherIcon(pixelSize: 4.0);
-        if (!IsLightweightLiveProgressMode(runTab))
-        {
-            liveIcon.BeginAnimation(UIElement.OpacityProperty,
-                new DoubleAnimation(1.0, 0.35, TimeSpan.FromMilliseconds(750))
-                { AutoReverse = true, RepeatBehavior = System.Windows.Media.Animation.RepeatBehavior.Forever,
-                  EasingFunction = new System.Windows.Media.Animation.SineEase() });
-        }
-        Grid.SetColumn(liveIcon, 0);
-        headerGrid.Children.Add(liveIcon);
-
-        var (agentName, _, _) = GetAgentIdentity();
-        var nameTb = new TextBlock
-        {
-            Text = agentName,
-            FontSize = 11,
-            FontWeight = FontWeights.SemiBold,
-            Foreground = secondaryText,
-            Margin = new Thickness(6, 0, 0, 0),
-            VerticalAlignment = VerticalAlignment.Center,
-        };
-        Grid.SetColumn(nameTb, 1);
-        headerGrid.Children.Add(nameTb);
-
-        _agentLiveElapsedText = new TextBlock
-        {
-            Text = "",
-            FontSize = 10,
-            Foreground = secondaryText,
-            Opacity = 0.50,
-            HorizontalAlignment = HorizontalAlignment.Right,
-            VerticalAlignment = VerticalAlignment.Center,
-        };
-        Grid.SetColumn(_agentLiveElapsedText, 2);
-        headerGrid.Children.Add(_agentLiveElapsedText);
-        container.Children.Add(headerGrid);
-
-        // 내용 카드
-        var card = new Border
-        {
-            BorderBrush = borderBrush,
-            BorderThickness = new Thickness(1),
-            CornerRadius = new CornerRadius(12),
-            Padding = new Thickness(13, 10, 13, 10),
-        };
-        card.SetResourceReference(Border.BackgroundProperty, "ItemBackground");
-
-        var cardStack = new StackPanel();
-
-        _agentLiveStatusText = new TextBlock
-        {
-            Text = "준비 중...",
-            FontSize = 12,
-            FontFamily = new System.Windows.Media.FontFamily("Segoe UI, Malgun Gothic"),
-            Foreground = secondaryText,
-            TextWrapping = TextWrapping.Wrap,
-        };
-        cardStack.Children.Add(_agentLiveStatusText);
-
-        _agentLiveSubItems = new StackPanel { Margin = new Thickness(0, 6, 0, 0) };
-        cardStack.Children.Add(_agentLiveSubItems);
-
-        card.Child = cardStack;
-        container.Children.Add(card);
-
-        _agentLiveContainer = container;
-        AddTranscriptElement(container);
-        ForceScrollToEnd();
-
-        // 경과 시간 타이머
-        _agentLiveElapsedTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
-        _agentLiveElapsedTimer.Tick += (_, _) =>
-        {
-            if (_agentLiveElapsedText != null)
-            {
-                var sec = (int)(DateTime.UtcNow - _agentLiveStartTime).TotalSeconds;
-                _agentLiveElapsedText.Text = sec > 0 ? $"{sec}초 경과" : "";
-            }
-        };
-        _agentLiveElapsedTimer.Start();
-    }
-
-    private void UpdateAgentLiveCard(string message, string? subItem = null,
-                                     string? category = null, bool clearSubItems = false)
-    {
-        if (_agentLiveContainer == null || _agentLiveStatusText == null) return;
-
-        _agentLiveStatusText.Text = message;
-
-        if (clearSubItems || (category != null && category != _agentLiveCurrentCategory))
-        {
-            _agentLiveSubItemTexts.Clear();
-            _agentLiveSubItems?.Children.Clear();
-            if (category != null) _agentLiveCurrentCategory = category;
-        }
-
-        if (!string.IsNullOrEmpty(subItem) && !_agentLiveSubItemTexts.Contains(subItem))
-        {
-            _agentLiveSubItemTexts.Add(subItem);
-            const int maxLiveSubItems = 8;
-            if (_agentLiveSubItemTexts.Count > maxLiveSubItems)
-            {
-                _agentLiveSubItemTexts.RemoveAt(0);
-                if (_agentLiveSubItems?.Children.Count > 0)
-                    _agentLiveSubItems.Children.RemoveAt(0);
-            }
-
-            var secondary = TryFindResource("SecondaryText") as Brush ?? Brushes.Gray;
-            var tb = new TextBlock
-            {
-                Text = $"› {subItem}",
-                FontSize = 10.5,
-                FontFamily = new System.Windows.Media.FontFamily("Segoe UI, Malgun Gothic"),
-                Foreground = secondary,
-                Opacity = 0.62,
-                TextTrimming = TextTrimming.CharacterEllipsis,
-                MaxWidth = 520,
-                Margin = new Thickness(0, 1, 0, 0),
-            };
-            _agentLiveSubItems?.Children.Add(tb);
-            ForceScrollToEnd();
-        }
-    }
-
-    private void RemoveAgentLiveCard(bool animated = true)
-    {
-        _agentLiveElapsedTimer?.Stop();
-        _agentLiveElapsedTimer = null;
-
-        if (_agentLiveContainer == null) return;
-        var toRemove = _agentLiveContainer;
-        _agentLiveContainer = null;
-        _agentLiveStatusText = null;
-        _agentLiveSubItems = null;
-        _agentLiveElapsedText = null;
-        _agentLiveSubItemTexts.Clear();
-        _agentLiveCurrentCategory = null;
-
-        if (animated && ContainsTranscriptElement(toRemove) && !IsLightweightLiveProgressMode())
-        {
-            var anim = new DoubleAnimation(toRemove.Opacity, 0, TimeSpan.FromMilliseconds(160));
-            anim.Completed += (_, _) => RemoveTranscriptElement(toRemove);
-            toRemove.BeginAnimation(UIElement.OpacityProperty, anim);
-        }
-        else
-        {
-            RemoveTranscriptElement(toRemove);
-        }
-    }
-
     // ─── 미니 다이아몬드 아이콘 애니메이션 ───────────────────────────────────────
 
     private void StartStatusDiamondAnimation()

src/AxCopilot/Views/TranscriptVisualHost.cs

@@ -0,0 +1,30 @@
+using System.Windows;
+using System.Windows.Controls;
+
+namespace AxCopilot.Views;
+
+public sealed class TranscriptVisualHost : ContentControl
+{
+    public TranscriptVisualHost()
+    {
+        DataContextChanged += (_, _) => SyncContent();
+        Loaded += (_, _) => SyncContent();
+    }
+
+    private void SyncContent()
+    {
+        if (DataContext is TranscriptVisualItem item)
+        {
+            Content = item.GetOrCreateElement();
+            return;
+        }
+
+        if (DataContext is UIElement element)
+        {
+            Content = element;
+            return;
+        }
+
+        Content = null;
+    }
+}

src/AxCopilot/Views/TranscriptVisualItem.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Windows;
+
+namespace AxCopilot.Views;
+
+public sealed class TranscriptVisualItem
+{
+    private readonly Func<UIElement>? _factory;
+    private readonly Action<UIElement>? _onMaterialized;
+    private UIElement? _element;
+
+    public TranscriptVisualItem(string key, UIElement element)
+    {
+        Key = key;
+        _element = element;
+    }
+
+    public TranscriptVisualItem(string key, Func<UIElement> factory, Action<UIElement>? onMaterialized = null)
+    {
+        Key = key;
+        _factory = factory;
+        _onMaterialized = onMaterialized;
+    }
+
+    public string Key { get; }
+
+    public bool IsMaterialized => _element != null;
+
+    public UIElement? Element => _element;
+
+    public UIElement GetOrCreateElement()
+    {
+        if (_element != null)
+            return _element;
+
+        if (_factory == null)
+            throw new InvalidOperationException("Transcript visual factory is not available.");
+
+        _element = _factory();
+        _onMaterialized?.Invoke(_element);
+        return _element;
+    }
+}