AX Agent 구조를 claw-code 기준으로 추가 정리해 transcript 렌더와 tool streaming 책임을 분리함

- ChatWindow.TranscriptRendering partial을 추가해 transcript windowing, 증분 렌더, 스크롤 보존 로직을 메인 ChatWindow.xaml.cs에서 분리
- StreamingToolExecutionCoordinator를 도입해 read-only 도구 prefetch, tool-use 스트리밍 수신, context overflow/transient error 복구를 별도 계층으로 이동
- AgentLoopRuntimeThresholds helper를 추가해 no-tool, plan retry, terminal evidence gate 임계값 계산을 AgentLoopService에서 분리
- AgentLoopTransitions.Execution은 coordinator thin wrapper 중심 구조로 정리해 이후 executor 고도화와 정책 변경이 덜 위험하도록 개선
- README와 docs/DEVELOPMENT.md를 2026-04-09 09:14 (KST) 기준으로 갱신
- 검증: 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.TranscriptRendering.cs

@@ -0,0 +1,169 @@
+using System.Windows.Threading;
+using AxCopilot.Models;
+using AxCopilot.Services;
+
+namespace AxCopilot.Views;
+
+public partial class ChatWindow
+{
+    private int GetActiveTimelineRenderLimit()
+    {
+        if (!_isStreaming)
+            return _timelineRenderLimit;
+
+        var streamingLimit = IsLightweightLiveProgressMode()
+            ? TimelineLightweightStreamingRenderLimit
+            : TimelineStreamingRenderLimit;
+        return Math.Min(_timelineRenderLimit, streamingLimit);
+    }
+
+    private void RenderMessages(bool preserveViewport = false)
+    {
+        var previousScrollableHeight = GetTranscriptScrollableHeight();
+        var previousVerticalOffset = GetTranscriptVerticalOffset();
+
+        ChatConversation? conv;
+        lock (_convLock) conv = _currentConversation;
+        _appState.RestoreAgentRunHistory(conv?.AgentRunHistory);
+
+        var visibleMessages = GetVisibleTimelineMessages(conv);
+        var visibleEvents = GetVisibleTimelineEvents(conv);
+
+        if (_isStreaming && preserveViewport
+            && visibleMessages.Count == _lastRenderedMessageCount
+            && visibleEvents.Count == _lastRenderedEventCount
+            && (conv?.ShowExecutionHistory ?? true) == _lastRenderedShowHistory
+            && string.Equals(_lastRenderedConversationId, conv?.Id, StringComparison.OrdinalIgnoreCase))
+            return;
+
+        if (conv == null || (visibleMessages.Count == 0 && visibleEvents.Count == 0))
+        {
+            ClearTranscriptElements();
+            _runBannerAnchors.Clear();
+            _lastRenderedTimelineKeys.Clear();
+            _lastRenderedMessageCount = 0;
+            _lastRenderedEventCount = 0;
+            EmptyState.Visibility = System.Windows.Visibility.Visible;
+            return;
+        }
+
+        if (!string.Equals(_lastRenderedConversationId, conv.Id, StringComparison.OrdinalIgnoreCase))
+        {
+            _lastRenderedConversationId = conv.Id;
+            _timelineRenderLimit = TimelineRenderPageSize;
+            _elementCache.Clear();
+            _lastRenderedTimelineKeys.Clear();
+            _lastRenderedMessageCount = 0;
+            _lastRenderedEventCount = 0;
+            InvalidateTimelineCache();
+        }
+
+        var showHistory = conv.ShowExecutionHistory;
+        EmptyState.Visibility = System.Windows.Visibility.Collapsed;
+
+        var orderedTimeline = BuildTimelineRenderActions(visibleMessages, visibleEvents);
+        var effectiveRenderLimit = GetActiveTimelineRenderLimit();
+        var hiddenCount = Math.Max(0, orderedTimeline.Count - effectiveRenderLimit);
+        var visibleTimeline = hiddenCount > 0
+            ? orderedTimeline.GetRange(hiddenCount, orderedTimeline.Count - hiddenCount)
+            : orderedTimeline;
+        var newKeys = new List<string>(visibleTimeline.Count);
+        foreach (var t in visibleTimeline)
+            newKeys.Add(t.Key);
+
+        var incremented = false;
+        var hasExternalChildren = _agentLiveContainer != null && ContainsTranscriptElement(_agentLiveContainer);
+        var expectedChildCount = _lastRenderedTimelineKeys.Count + (_lastRenderedHiddenCount > 0 ? 1 : 0);
+        var canIncremental = !hasExternalChildren
+            && _lastRenderedTimelineKeys.Count > 0
+            && newKeys.Count >= _lastRenderedTimelineKeys.Count
+            && _lastRenderedHiddenCount == hiddenCount
+            && GetTranscriptElementCount() == expectedChildCount;
+
+        if (canIncremental)
+        {
+            var prevLiveCount = 0;
+            for (var i = _lastRenderedTimelineKeys.Count - 1; i >= 0; i--)
+            {
+                if (_lastRenderedTimelineKeys[i].StartsWith("_live_", StringComparison.Ordinal))
+                    prevLiveCount++;
+                else
+                    break;
+            }
+
+            var prevStableCount = _lastRenderedTimelineKeys.Count - prevLiveCount;
+            var prefixMatch = true;
+            for (var i = 0; i < prevStableCount; i++)
+            {
+                if (i >= newKeys.Count || !string.Equals(_lastRenderedTimelineKeys[i], newKeys[i], StringComparison.Ordinal))
+                {
+                    prefixMatch = false;
+                    break;
+                }
+            }
+
+            if (prefixMatch)
+            {
+                try
+                {
+                    for (var r = 0; r < prevLiveCount && GetTranscriptElementCount() > 0; r++)
+                        RemoveTranscriptElementAt(GetTranscriptElementCount() - 1);
+
+                    for (var i = prevStableCount; i < visibleTimeline.Count; i++)
+                        visibleTimeline[i].Render();
+
+                    _lastRenderedTimelineKeys = newKeys;
+                    _lastRenderedHiddenCount = hiddenCount;
+                    _lastRenderedMessageCount = visibleMessages.Count;
+                    _lastRenderedEventCount = visibleEvents.Count;
+                    _lastRenderedShowHistory = showHistory;
+                    incremented = true;
+                }
+                catch (Exception ex)
+                {
+                    LogService.Warn($"증분 렌더링 실패, 전체 재빌드로 전환: {ex.Message}");
+                    _lastRenderedTimelineKeys.Clear();
+                    incremented = false;
+                }
+            }
+        }
+
+        if (!incremented)
+        {
+            ClearTranscriptElements();
+            _runBannerAnchors.Clear();
+
+            if (hiddenCount > 0)
+                AddTranscriptElement(CreateTimelineLoadMoreCard(hiddenCount));
+
+            foreach (var item in visibleTimeline)
+                item.Render();
+
+            if (_agentLiveContainer != null && !ContainsTranscriptElement(_agentLiveContainer))
+                AddTranscriptElement(_agentLiveContainer);
+
+            _lastRenderedTimelineKeys = newKeys;
+            _lastRenderedHiddenCount = hiddenCount;
+            _lastRenderedMessageCount = visibleMessages.Count;
+            _lastRenderedEventCount = visibleEvents.Count;
+            _lastRenderedShowHistory = showHistory;
+        }
+
+        if (!preserveViewport)
+        {
+            _ = Dispatcher.InvokeAsync(ScrollTranscriptToEnd, DispatcherPriority.Background);
+            return;
+        }
+
+        _ = Dispatcher.InvokeAsync(() =>
+        {
+            if (_transcriptScrollViewer == null)
+                return;
+
+            var newScrollableHeight = GetTranscriptScrollableHeight();
+            var delta = newScrollableHeight - previousScrollableHeight;
+            var targetOffset = Math.Max(0, previousVerticalOffset + Math.Max(0, delta));
+            ScrollTranscriptToVerticalOffset(targetOffset);
+        }, DispatcherPriority.Background);
+    }
+}