AX Agent loop 정책을 분리하고 transcript 가상화·성능 계측 구조를 강화한다

- AgentLoop 검증/문서/compact 정책 메서드를 partial 파일로 분리해 loop 본문의 책임을 줄임
- transcript 렌더에 cache pruning과 deferred scrolling을 적용해 긴 세션의 UI 부담을 낮춤
- AgentPerformanceLogService를 추가해 transcript 렌더와 agent loop 실행 요약을 perf 로그로 남김
- README와 DEVELOPMENT 문서에 2026-04-09 10:08 (KST) 기준 구조 개선 및 계측 이력을 반영함
- dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\\ 검증 결과 경고 0개 오류 0개

README.md

@@ -1531,3 +1531,8 @@ MIT License
   - transcript 렌더 구조를 planning/execution 단계로 한 번 더 쪼갰습니다. [ChatWindow.TranscriptRenderPlanner.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptRenderPlanner.cs) 에서 visible window 계산, render key 집계, 전체/증분 렌더 계획 생성을 맡기고, [ChatWindow.TranscriptRenderExecution.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptRenderExecution.cs) 에서 host 적용과 viewport 보존을 맡기도록 정리했습니다.
   - [ChatWindow.TranscriptRendering.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptRendering.cs)의 `RenderMessages()`는 이제 `데이터 수집 -> render plan 생성 -> 증분/전체 적용`만 오케스트레이션하는 얇은 진입점이 됐습니다.
   - `claw-code`의 `Messages.tsx`와 `VirtualMessageList.tsx`처럼 transcript planning과 실제 host 조작을 분리하는 방향에 더 가까워졌고, 이후 실제 가상화 윈도우 정책을 다듬을 때 변경 범위를 더 안전하게 제한할 수 있게 됐습니다.
+- 업데이트: 2026-04-09 10:08 (KST)
+  - 구조 개선과 실검증을 함께 하기 위해 loop 정책과 transcript 호스트에 성능 계측을 추가했습니다. [AgentPerformanceLogService.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/AgentPerformanceLogService.cs)가 `%APPDATA%\\AxCopilot\\perf`에 transcript 렌더 시간과 agent loop 실행 요약을 JSON 로그로 남깁니다.
+  - [AgentLoopTransitions.Verification.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopTransitions.Verification.cs), [AgentLoopTransitions.Documents.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopTransitions.Documents.cs), [AgentLoopCompactionPolicy.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopCompactionPolicy.cs)로 검증/fallback/compact 정책 메서드를 분리해 [AgentLoopService.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopService.cs)의 책임을 더 줄였습니다.
+  - [ChatWindow.TranscriptVirtualization.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptVirtualization.cs)에서 off-screen 버블 캐시를 pruning하도록 바꿨고, [ChatWindow.xaml](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.xaml)의 transcript `ListBox`에는 deferred scrolling과 작은 cache length를 적용해 더 강한 가상화 리스트 방향으로 정리했습니다.
+  - [ChatWindow.TranscriptRendering.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptRendering.cs)는 렌더 시간, visible message/event 수, hidden count, lightweight mode 여부를 함께 기록해 실사용 세션에서 버벅임을 실제 수치로 판단할 수 있게 됐습니다.

docs/DEVELOPMENT.md

@@ -5536,3 +5536,25 @@ ow + toggle ?쒓컖 ?몄뼱濡??ㅼ떆 ?뺣젹?덈떎.
 - 구조 효과
   - transcript 렌더의 변경 포인트가 `계획 생성`과 `실행 적용`으로 명확히 나뉘었다.
   - 향후 실제 가상화 강화, render batching, incremental diff 정교화 작업을 더 안전하게 진행할 수 있다.
+
+## 2026-04-09 10:08 (KST)
+
+- [AgentPerformanceLogService.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/AgentPerformanceLogService.cs)
+  - `%APPDATA%\AxCopilot\perf\performance-YYYY-MM-DD.json`에 transcript 렌더 및 agent loop 성능 로그를 남기는 전용 서비스를 추가했다.
+  - 구조 개선 후 실제 Cowork/Code 세션에서 렌더 시간과 루프 duration을 수치로 확인할 수 있게 해, 향후 병목 판단을 코드 추정이 아니라 로그 기반으로 할 수 있게 했다.
+- [ChatWindow.TranscriptVirtualization.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptVirtualization.cs)
+  - transcript에 보이지 않는 오래된 버블 캐시를 pruning하는 정책을 추가했다.
+  - `_elementCache`가 실행 중 계속 커지는 대신 최근 visible/rendered key 위주로 유지되도록 바꿔, 긴 세션에서 메모리와 visual 재사용 비용을 더 안정적으로 관리하게 했다.
+- [ChatWindow.TranscriptRendering.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.TranscriptRendering.cs)
+  - `RenderMessages()`에 `Stopwatch` 기반 계측을 추가하고, 렌더 시간이 24ms 이상이거나 스트리밍 중이면 transcript 성능 로그를 남기도록 했다.
+  - 로그 detail에는 `visibleMessages`, `visibleEvents`, `renderedItems`, `hiddenCount`, `lightweight` 여부가 포함돼 transcript 버벅임의 실제 상황을 재현하기 쉬워졌다.
+- [ChatWindow.xaml](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Views/ChatWindow.xaml)
+  - transcript `ListBox`에 `ScrollViewer.IsDeferredScrollingEnabled`, `VirtualizingPanel.CacheLength`, `VirtualizingPanel.CacheLengthUnit`을 추가해 가상화 리스트 동작을 더 보수적으로 조정했다.
+- [AgentLoopTransitions.Verification.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopTransitions.Verification.cs)
+- [AgentLoopTransitions.Documents.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopTransitions.Documents.cs)
+- [AgentLoopCompactionPolicy.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopCompactionPolicy.cs)
+  - `AgentLoopService`에 몰려 있던 검증 gate, 문서 fallback/후속 실행, post-compaction 정책 메서드를 partial 단위로 분리했다.
+  - 결과적으로 loop 본문은 정책 소비자에 더 가까워졌고, 향후 `claw-code`식 executor/verification/fallback 분해를 더 안전하게 진행할 수 있는 구조가 됐다.
+- [AgentLoopService.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopService.cs)
+  - 루프 finally 단계에서 `run_summary` 성능 로그를 남기도록 보강했다.
+  - iteration 수, tool 호출 수, 토큰 사용량, post-compaction suppression 수치가 함께 기록돼 사내 모델에서 `느린데 왜 느린지`를 나중에 역추적할 수 있다.

src/AxCopilot/Services/Agent/AgentLoopCompactionPolicy.cs

@@ -0,0 +1,116 @@
+namespace AxCopilot.Services.Agent;
+
+public partial class AgentLoopService
+{
+    private void MarkRunPostCompaction(ContextCompactionResult result, RunState runState)
+    {
+        runState.PendingPostCompactionTurn = true;
+        runState.PostCompactionTurnCounter = 0;
+        runState.LastCompactionStageSummary = result.StageSummary;
+        runState.LastCompactionSavedTokens = result.SavedTokens;
+        SyncRunPostCompactionState(runState);
+    }
+
+    private void NotifyPostCompactionTurnIfNeeded(RunState runState)
+    {
+        if (!runState.PendingPostCompactionTurn)
+            return;
+
+        runState.PendingPostCompactionTurn = false;
+        runState.PostCompactionTurnCounter++;
+        SyncRunPostCompactionState(runState);
+
+        var stage = string.IsNullOrWhiteSpace(runState.LastCompactionStageSummary)
+            ? "기본"
+            : runState.LastCompactionStageSummary;
+        var saved = runState.LastCompactionSavedTokens > 0
+            ? $" · {Services.TokenEstimator.Format(runState.LastCompactionSavedTokens)} tokens 절감"
+            : "";
+        EmitEvent(
+            AgentEventType.Thinking,
+            "",
+            $"compact 이후 {runState.PostCompactionTurnCounter}번째 턴 · {stage}{saved}");
+    }
+
+    private void SyncRunPostCompactionState(RunState runState)
+    {
+        _runPendingPostCompactionTurn = runState.PendingPostCompactionTurn;
+        _runPostCompactionTurnCounter = runState.PostCompactionTurnCounter;
+        _runLastCompactionStageSummary = runState.LastCompactionStageSummary ?? "";
+        _runLastCompactionSavedTokens = runState.LastCompactionSavedTokens;
+        _runPostCompactionToolResultCompactions = runState.PostCompactionToolResultCompactions;
+    }
+
+    private bool ShouldSuppressPostCompactionThinking(string summary)
+    {
+        if (string.IsNullOrWhiteSpace(summary))
+            return false;
+
+        var postCompactActive = _runPendingPostCompactionTurn || _runPostCompactionTurnCounter > 0;
+        if (!postCompactActive)
+            return false;
+
+        if (_runPostCompactionTurnCounter > 1)
+            return false;
+
+        return summary.StartsWith("LLM에 요청 중", StringComparison.Ordinal)
+               || summary.StartsWith("사용자 프롬프트 제출", StringComparison.Ordinal)
+               || summary.StartsWith("무료 티어 모드", StringComparison.Ordinal)
+               || summary.StartsWith("컨텍스트 압축 완료", StringComparison.Ordinal);
+    }
+
+    private string BuildLoopToolResultMessage(LlmService.ContentBlock call, ToolResult result, RunState runState)
+    {
+        var output = result.Output ?? "";
+        if (!ShouldCompactToolResultForPostCompactionTurn(runState, call.ToolName, output))
+            return TruncateOutput(output, 4000);
+
+        runState.PostCompactionToolResultCompactions++;
+        SyncRunPostCompactionState(runState);
+
+        var compacted = CompactToolResultForPostCompaction(call.ToolName, output);
+        var stage = string.IsNullOrWhiteSpace(runState.LastCompactionStageSummary)
+            ? "compact"
+            : runState.LastCompactionStageSummary;
+        return $"[POST_COMPACTION_TOOL_RESULT:{call.ToolName}] {stage}\n{compacted}";
+    }
+
+    private static bool ShouldCompactToolResultForPostCompactionTurn(RunState runState, string toolName, string output)
+    {
+        if (runState.PostCompactionTurnCounter != 1)
+            return false;
+        if (string.IsNullOrWhiteSpace(output))
+            return false;
+        if (output.Length < 900)
+            return false;
+
+        return toolName is "process" or "build_run" or "test_loop" or "snippet_runner" or "git_tool" or "http_tool"
+               || output.Length > 1800;
+    }
+
+    private static string CompactToolResultForPostCompaction(string toolName, string output)
+    {
+        var normalized = output.Replace("\r\n", "\n");
+        var lines = normalized.Split('\n', StringSplitOptions.None)
+            .Select(line => line.TrimEnd())
+            .Where(line => !string.IsNullOrWhiteSpace(line))
+            .ToList();
+
+        if (lines.Count == 0)
+            return TruncateOutput(output, 1200);
+
+        var headCount = toolName is "build_run" or "test_loop" or "process" ? 6 : 4;
+        var tailCount = toolName is "build_run" or "test_loop" or "process" ? 4 : 3;
+        var kept = new List<string>();
+        kept.AddRange(lines.Take(headCount));
+
+        if (lines.Count > headCount + tailCount)
+            kept.Add($"...[post-compact snip: {lines.Count - headCount - tailCount:N0}줄 생략]...");
+
+        if (lines.Count > headCount)
+            kept.AddRange(lines.Skip(Math.Max(headCount, lines.Count - tailCount)));
+
+        var compacted = string.Join("\n", kept.Distinct(StringComparer.Ordinal));
+        return TruncateOutput(compacted, 1400);
+    }
+}

src/AxCopilot/Services/Agent/AgentLoopService.cs

@@ -156,6 +156,7 @@ public partial class AgentLoopService
     {
         if (IsRunning) throw new InvalidOperationException("에이전트가 이미 실행 중입니다.");
 
+        var runStopwatch = Stopwatch.StartNew();
         IsRunning = true;
         _currentRunId = Guid.NewGuid().ToString("N");
         _docFallbackAttempted = false;
@@ -1741,6 +1742,30 @@ public partial class AgentLoopService
                     EmitEvent(AgentEventType.StepDone, "total_stats", summary);
                 }
             }
+
+            runStopwatch.Stop();
+            AgentPerformanceLogService.LogMetric(
+                "agent_loop",
+                "run_summary",
+                _conversationId,
+                ActiveTab ?? "",
+                runStopwatch.ElapsedMilliseconds,
+                new
+                {
+                    runId = _currentRunId,
+                    iterations = iteration,
+                    toolCalls = totalToolCalls,
+                    toolSuccess = statsSuccessCount,
+                    toolFail = statsFailCount,
+                    inputTokens = statsInputTokens,
+                    outputTokens = statsOutputTokens,
+                    repeatedFailureBlocks = statsRepeatedFailureBlocks,
+                    recoveredAfterFailure = statsRecoveredAfterFailure,
+                    postCompactionNoiseSuppressed = _runPostCompactionSuppressedThinkingCount,
+                    postCompactionToolResultCompactions = _runPostCompactionToolResultCompactions,
+                    taskType = taskPolicy.TaskType,
+                    model = _settings.Settings.Llm.Model ?? "",
+                });
         }
     }
 
@@ -4619,118 +4644,6 @@ public partial class AgentLoopService
         }
     }
 
-    private void MarkRunPostCompaction(ContextCompactionResult result, RunState runState)
-    {
-        runState.PendingPostCompactionTurn = true;
-        runState.PostCompactionTurnCounter = 0;
-        runState.LastCompactionStageSummary = result.StageSummary;
-        runState.LastCompactionSavedTokens = result.SavedTokens;
-        SyncRunPostCompactionState(runState);
-    }
-
-    private void NotifyPostCompactionTurnIfNeeded(RunState runState)
-    {
-        if (!runState.PendingPostCompactionTurn)
-            return;
-
-        runState.PendingPostCompactionTurn = false;
-        runState.PostCompactionTurnCounter++;
-        SyncRunPostCompactionState(runState);
-
-        var stage = string.IsNullOrWhiteSpace(runState.LastCompactionStageSummary)
-            ? "기본"
-            : runState.LastCompactionStageSummary;
-        var saved = runState.LastCompactionSavedTokens > 0
-            ? $" · {Services.TokenEstimator.Format(runState.LastCompactionSavedTokens)} tokens 절감"
-            : "";
-        EmitEvent(
-            AgentEventType.Thinking,
-            "",
-            $"compact 이후 {runState.PostCompactionTurnCounter}번째 턴 · {stage}{saved}");
-    }
-
-    private void SyncRunPostCompactionState(RunState runState)
-    {
-        _runPendingPostCompactionTurn = runState.PendingPostCompactionTurn;
-        _runPostCompactionTurnCounter = runState.PostCompactionTurnCounter;
-        _runLastCompactionStageSummary = runState.LastCompactionStageSummary ?? "";
-        _runLastCompactionSavedTokens = runState.LastCompactionSavedTokens;
-        _runPostCompactionToolResultCompactions = runState.PostCompactionToolResultCompactions;
-    }
-
-    private bool ShouldSuppressPostCompactionThinking(string summary)
-    {
-        if (string.IsNullOrWhiteSpace(summary))
-            return false;
-
-        var postCompactActive = _runPendingPostCompactionTurn || _runPostCompactionTurnCounter > 0;
-        if (!postCompactActive)
-            return false;
-
-        if (_runPostCompactionTurnCounter > 1)
-            return false;
-
-        return summary.StartsWith("LLM에 요청 중", StringComparison.Ordinal)
-               || summary.StartsWith("사용자 프롬프트 제출", StringComparison.Ordinal)
-               || summary.StartsWith("무료 티어 모드", StringComparison.Ordinal)
-               || summary.StartsWith("컨텍스트 압축 완료", StringComparison.Ordinal);
-    }
-
-    private string BuildLoopToolResultMessage(LlmService.ContentBlock call, ToolResult result, RunState runState)
-    {
-        var output = result.Output ?? "";
-        if (!ShouldCompactToolResultForPostCompactionTurn(runState, call.ToolName, output))
-            return TruncateOutput(output, 4000);
-
-        runState.PostCompactionToolResultCompactions++;
-        SyncRunPostCompactionState(runState);
-
-        var compacted = CompactToolResultForPostCompaction(call.ToolName, output);
-        var stage = string.IsNullOrWhiteSpace(runState.LastCompactionStageSummary)
-            ? "compact"
-            : runState.LastCompactionStageSummary;
-        return $"[POST_COMPACTION_TOOL_RESULT:{call.ToolName}] {stage}\n{compacted}";
-    }
-
-    private static bool ShouldCompactToolResultForPostCompactionTurn(RunState runState, string toolName, string output)
-    {
-        if (runState.PostCompactionTurnCounter != 1)
-            return false;
-        if (string.IsNullOrWhiteSpace(output))
-            return false;
-        if (output.Length < 900)
-            return false;
-
-        return toolName is "process" or "build_run" or "test_loop" or "snippet_runner" or "git_tool" or "http_tool"
-               || output.Length > 1800;
-    }
-
-    private static string CompactToolResultForPostCompaction(string toolName, string output)
-    {
-        var normalized = output.Replace("\r\n", "\n");
-        var lines = normalized.Split('\n', StringSplitOptions.None)
-            .Select(line => line.TrimEnd())
-            .Where(line => !string.IsNullOrWhiteSpace(line))
-            .ToList();
-
-        if (lines.Count == 0)
-            return TruncateOutput(output, 1200);
-
-        var headCount = toolName is "build_run" or "test_loop" or "process" ? 6 : 4;
-        var tailCount = toolName is "build_run" or "test_loop" or "process" ? 4 : 3;
-        var kept = new List<string>();
-        kept.AddRange(lines.Take(headCount));
-
-        if (lines.Count > headCount + tailCount)
-            kept.Add($"...[post-compact snip: {lines.Count - headCount - tailCount:N0}줄 생략]...");
-
-        if (lines.Count > headCount)
-            kept.AddRange(lines.Skip(Math.Max(headCount, lines.Count - tailCount)));
-
-        var compacted = string.Join("\n", kept.Distinct(StringComparer.Ordinal));
-        return TruncateOutput(compacted, 1400);
-    }
-
     /// <summary>영향 범위 기반 의사결정 체크. 확인이 필요하면 메시지를 반환, 불필요하면 null.</summary>
     private string? CheckDecisionRequired(LlmService.ContentBlock call, AgentContext context)
     {

src/AxCopilot/Services/Agent/AgentLoopTransitions.Documents.cs

@@ -0,0 +1,156 @@
+using AxCopilot.Models;
+
+namespace AxCopilot.Services.Agent;
+
+public partial class AgentLoopService
+{
+    private void ApplyDocumentPlanSuccessTransitions(
+        LlmService.ContentBlock call,
+        ToolResult result,
+        List<ChatMessage> messages,
+        ref bool documentPlanCalled,
+        ref string? documentPlanPath,
+        ref string? documentPlanTitle,
+        ref string? documentPlanScaffold)
+    {
+        if (!string.Equals(call.ToolName, "document_plan", StringComparison.OrdinalIgnoreCase))
+            return;
+
+        documentPlanCalled = true;
+        var po = result.Output ?? string.Empty;
+        var pm = System.Text.RegularExpressions.Regex.Match(po, @"path:\s*""([^""]+)""");
+        if (pm.Success) documentPlanPath = pm.Groups[1].Value;
+        var tm = System.Text.RegularExpressions.Regex.Match(po, @"title:\s*""([^""]+)""");
+        if (tm.Success) documentPlanTitle = tm.Groups[1].Value;
+        documentPlanScaffold = ExtractDocumentPlanScaffold(po);
+
+        if (!ContainsDocumentPlanFollowUpInstruction(po))
+            return;
+
+        var toolHint = ResolveDocumentPlanFollowUpTool(po);
+        messages.Add(new ChatMessage
+        {
+            Role = "user",
+            Content =
+                "document_plan이 완료되었습니다. " +
+                "방금 생성된 골격의 [내용...] 자리와 각 섹션 내용을 실제 상세 본문으로 모두 채운 뒤 " +
+                $"{toolHint} 도구를 지금 즉시 호출하세요. " +
+                "설명만 하지 말고 실제 문서 생성 도구 호출로 바로 이어가세요."
+        });
+        EmitEvent(AgentEventType.Thinking, "", $"문서 개요 완료 · {toolHint} 실행 유도");
+    }
+
+    private static string? ExtractDocumentPlanScaffold(string output)
+    {
+        if (string.IsNullOrWhiteSpace(output))
+            return null;
+
+        var markers = new (string Start, string End)[]
+        {
+            ("--- body 시작 ---", "--- body 끝 ---"),
+            ("--- body start ---", "--- body end ---"),
+            ("<!-- body start marker -->", "<!-- body end marker -->"),
+        };
+
+        foreach (var (startMarker, endMarker) in markers)
+        {
+            var start = output.IndexOf(startMarker, StringComparison.OrdinalIgnoreCase);
+            if (start < 0)
+                continue;
+
+            var contentStart = start + startMarker.Length;
+            var end = output.IndexOf(endMarker, contentStart, StringComparison.OrdinalIgnoreCase);
+            if (end <= contentStart)
+                continue;
+
+            var scaffold = output[contentStart..end].Trim();
+            if (!string.IsNullOrWhiteSpace(scaffold))
+                return scaffold;
+        }
+
+        return null;
+    }
+
+    private static bool ContainsDocumentPlanFollowUpInstruction(string output)
+    {
+        if (string.IsNullOrWhiteSpace(output))
+            return false;
+
+        return output.Contains("즉시 실행", StringComparison.OrdinalIgnoreCase)
+               || output.Contains("immediate next step", StringComparison.OrdinalIgnoreCase)
+               || output.Contains("call html_create", StringComparison.OrdinalIgnoreCase)
+               || output.Contains("call document_assemble", StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static string ResolveDocumentPlanFollowUpTool(string output)
+    {
+        if (output.Contains("document_assemble", StringComparison.OrdinalIgnoreCase))
+            return "document_assemble";
+        if (output.Contains("docx_create", StringComparison.OrdinalIgnoreCase))
+            return "docx_create";
+        if (output.Contains("markdown_create", StringComparison.OrdinalIgnoreCase))
+            return "markdown_create";
+        if (output.Contains("file_write", StringComparison.OrdinalIgnoreCase))
+            return "file_write";
+        return "html_create";
+    }
+
+    private async Task<(bool Completed, bool ConsumedExtraIteration)> TryHandleTerminalDocumentCompletionTransitionAsync(
+        LlmService.ContentBlock call,
+        ToolResult result,
+        List<LlmService.ContentBlock> toolCalls,
+        List<ChatMessage> messages,
+        Models.LlmSettings llm,
+        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy,
+        AgentContext context,
+        CancellationToken ct)
+    {
+        if (!result.Success || !IsTerminalDocumentTool(call.ToolName) || toolCalls.Count != 1)
+            return (false, false);
+
+        var verificationEnabled = executionPolicy.EnablePostToolVerification
+            && AgentTabSettingsResolver.IsPostToolVerificationEnabled(ActiveTab, llm);
+        var shouldVerify = ShouldRunPostToolVerification(
+            ActiveTab,
+            call.ToolName,
+            result.Success,
+            verificationEnabled,
+            verificationEnabled);
+        var consumedExtraIteration = false;
+        if (shouldVerify)
+        {
+            await RunPostToolVerificationAsync(messages, call.ToolName, result, context, ct);
+            consumedExtraIteration = true;
+        }
+
+        EmitEvent(AgentEventType.Complete, "", "에이전트 작업 완료");
+        return (true, consumedExtraIteration);
+    }
+
+    private async Task<bool> TryApplyPostToolVerificationTransitionAsync(
+        LlmService.ContentBlock call,
+        ToolResult result,
+        List<ChatMessage> messages,
+        Models.LlmSettings llm,
+        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy,
+        AgentContext context,
+        CancellationToken ct)
+    {
+        if (!result.Success)
+            return false;
+
+        var verificationEnabled = executionPolicy.EnablePostToolVerification
+            && AgentTabSettingsResolver.IsPostToolVerificationEnabled(ActiveTab, llm);
+        var shouldVerify = ShouldRunPostToolVerification(
+            ActiveTab,
+            call.ToolName,
+            result.Success,
+            verificationEnabled,
+            verificationEnabled);
+        if (!shouldVerify)
+            return false;
+
+        await RunPostToolVerificationAsync(messages, call.ToolName, result, context, ct);
+        return true;
+    }
+}

src/AxCopilot/Services/Agent/AgentLoopTransitions.Execution.cs

@@ -58,205 +58,6 @@ public partial class AgentLoopService
         return true;
     }
 
-    private bool TryApplyCodeCompletionGateTransition(
-        List<ChatMessage> messages,
-        string? textResponse,
-        TaskTypePolicy taskPolicy,
-        bool requireHighImpactCodeVerification,
-        int totalToolCalls,
-        RunState runState,
-        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
-    {
-        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase) || totalToolCalls <= 0)
-            return false;
-
-        var hasCodeVerificationEvidence = HasCodeVerificationEvidenceAfterLastModification(
-            messages,
-            requireHighImpactCodeVerification);
-        if (executionPolicy.CodeVerificationGateMaxRetries > 0
-            && !hasCodeVerificationEvidence
-            && runState.CodeVerificationGateRetry < executionPolicy.CodeVerificationGateMaxRetries)
-        {
-            runState.CodeVerificationGateRetry++;
-            if (!string.IsNullOrEmpty(textResponse))
-                messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-            messages.Add(new ChatMessage
-            {
-                Role = "user",
-                Content = requireHighImpactCodeVerification
-                    ? "[System:CodeQualityGate] 공용/핵심 코드 변경 이후 검증 근거가 부족합니다. 종료하지 말고 file_read, grep/glob, git diff, build/test까지 확인한 뒤에만 마무리하세요."
-                    : "[System:CodeQualityGate] 마지막 코드 수정 이후 build/test/file_read/diff 근거가 부족합니다. 종료하지 말고 검증 근거를 보강한 뒤에만 마무리하세요."
-            });
-            EmitEvent(AgentEventType.Thinking, "", requireHighImpactCodeVerification
-                ? "핵심 코드 변경의 검증 근거가 부족해 추가 검증을 진행합니다..."
-                : "코드 결과 검증 근거가 부족해 추가 검증을 진행합니다...");
-            return true;
-        }
-
-        if (requireHighImpactCodeVerification
-            && executionPolicy.HighImpactBuildTestGateMaxRetries > 0
-            && !HasSuccessfulBuildAndTestAfterLastModification(messages)
-            && runState.HighImpactBuildTestGateRetry < executionPolicy.HighImpactBuildTestGateMaxRetries)
-        {
-            runState.HighImpactBuildTestGateRetry++;
-            if (!string.IsNullOrEmpty(textResponse))
-                messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-            messages.Add(new ChatMessage
-            {
-                Role = "user",
-                Content = "[System:HighImpactBuildTestGate] 핵심 코드 변경입니다. 종료하지 말고 build_run과 test_loop를 모두 실행해 성공 근거를 확보한 뒤에만 마무리하세요."
-            });
-            EmitEvent(AgentEventType.Thinking, "", "핵심 변경이라 build+test 성공 근거를 모두 확보할 때까지 진행합니다...");
-            return true;
-        }
-
-        if (executionPolicy.FinalReportGateMaxRetries > 0
-            && !HasSufficientFinalReportEvidence(textResponse, taskPolicy, requireHighImpactCodeVerification, messages)
-            && runState.FinalReportGateRetry < executionPolicy.FinalReportGateMaxRetries)
-        {
-            runState.FinalReportGateRetry++;
-            if (!string.IsNullOrEmpty(textResponse))
-                messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-            messages.Add(new ChatMessage
-            {
-                Role = "user",
-                Content = BuildFinalReportQualityPrompt(taskPolicy, requireHighImpactCodeVerification)
-            });
-            EmitEvent(AgentEventType.Thinking, "", "최종 보고에 변경·검증·리스크 요약이 부족해 한 번 더 정리합니다...");
-            return true;
-        }
-
-        return false;
-    }
-
-    private bool TryApplyCodeDiffEvidenceGateTransition(
-        List<ChatMessage> messages,
-        string? textResponse,
-        RunState runState,
-        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
-    {
-        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase))
-            return false;
-
-        if (executionPolicy.CodeDiffGateMaxRetries <= 0 || runState.CodeDiffGateRetry >= executionPolicy.CodeDiffGateMaxRetries)
-            return false;
-
-        if (HasDiffEvidenceAfterLastModification(messages))
-            return false;
-
-        runState.CodeDiffGateRetry++;
-        if (!string.IsNullOrEmpty(textResponse))
-            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-        messages.Add(new ChatMessage
-        {
-            Role = "user",
-            Content = "[System:CodeDiffGate] 코드 변경 이후 diff 근거가 부족합니다. " +
-                      "git_tool 도구로 변경 파일과 핵심 diff를 먼저 확인하고 요약하세요. " +
-                      "지금 즉시 git_tool 도구를 호출하세요."
-        });
-        EmitEvent(AgentEventType.Thinking, "", "코드 diff 근거가 부족해 git diff 검증을 추가합니다...");
-        return true;
-    }
-
-    private bool TryApplyRecentExecutionEvidenceGateTransition(
-        List<ChatMessage> messages,
-        string? textResponse,
-        TaskTypePolicy taskPolicy,
-        RunState runState,
-        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
-    {
-        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase))
-            return false;
-
-        if (executionPolicy.RecentExecutionGateMaxRetries <= 0 || runState.RecentExecutionGateRetry >= executionPolicy.RecentExecutionGateMaxRetries)
-            return false;
-
-        if (!HasAnyBuildOrTestEvidence(messages))
-            return false;
-
-        if (HasBuildOrTestEvidenceAfterLastModification(messages))
-            return false;
-
-        runState.RecentExecutionGateRetry++;
-        if (!string.IsNullOrEmpty(textResponse))
-            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-        messages.Add(new ChatMessage
-        {
-            Role = "user",
-            Content = BuildRecentExecutionEvidencePrompt(taskPolicy)
-        });
-        EmitEvent(AgentEventType.Thinking, "", "최근 수정 이후 실행 근거가 부족해 build/test 재검증을 수행합니다...");
-        return true;
-    }
-
-    private bool TryApplyExecutionSuccessGateTransition(
-        List<ChatMessage> messages,
-        string? textResponse,
-        TaskTypePolicy taskPolicy,
-        RunState runState,
-        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
-    {
-        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase))
-            return false;
-
-        if (executionPolicy.ExecutionSuccessGateMaxRetries <= 0 || runState.ExecutionSuccessGateRetry >= executionPolicy.ExecutionSuccessGateMaxRetries)
-            return false;
-
-        if (!HasAnyBuildOrTestAttempt(messages))
-            return false;
-
-        if (HasAnyBuildOrTestEvidence(messages))
-            return false;
-
-        runState.ExecutionSuccessGateRetry++;
-        if (!string.IsNullOrEmpty(textResponse))
-            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-        messages.Add(new ChatMessage
-        {
-            Role = "user",
-            Content = BuildExecutionSuccessGatePrompt(taskPolicy)
-        });
-        EmitEvent(AgentEventType.Thinking, "", "실패한 실행 근거만 있어 build/test 성공 결과를 다시 검증합니다...");
-        return true;
-    }
-
-    private bool TryApplyTerminalEvidenceGateTransition(
-        List<ChatMessage> messages,
-        string? textResponse,
-        TaskTypePolicy taskPolicy,
-        string userQuery,
-        int totalToolCalls,
-        string? lastArtifactFilePath,
-        RunState runState,
-        int retryMax)
-    {
-        if (totalToolCalls <= 0)
-            return false;
-
-        if (ShouldSkipTerminalEvidenceGateForAnalysisQuery(userQuery, taskPolicy))
-            return false;
-
-        if (runState.TerminalEvidenceGateRetry >= retryMax)
-            return false;
-
-        if (HasTerminalProgressEvidence(taskPolicy, messages, lastArtifactFilePath))
-            return false;
-
-        runState.TerminalEvidenceGateRetry++;
-        if (!string.IsNullOrEmpty(textResponse))
-            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
-        messages.Add(new ChatMessage
-        {
-            Role = "user",
-            Content = BuildTerminalEvidenceGatePrompt(taskPolicy, lastArtifactFilePath)
-        });
-        EmitEvent(
-            AgentEventType.Thinking,
-            "",
-            $"종료 전 실행 증거가 부족해 보강 단계를 진행합니다 ({runState.TerminalEvidenceGateRetry}/{retryMax})");
-        return true;
-    }
-
     private static bool ShouldSkipTerminalEvidenceGateForAnalysisQuery(string userQuery, TaskTypePolicy taskPolicy)
     {
         if (string.Equals(taskPolicy.TaskType, "docs", StringComparison.OrdinalIgnoreCase))
@@ -1318,189 +1119,6 @@ public partial class AgentLoopService
                || lower.Contains("json parse");
     }
 
-    private void ApplyDocumentPlanSuccessTransitions(
-        LlmService.ContentBlock call,
-        ToolResult result,
-        List<ChatMessage> messages,
-        ref bool documentPlanCalled,
-        ref string? documentPlanPath,
-        ref string? documentPlanTitle,
-        ref string? documentPlanScaffold)
-    {
-        if (!string.Equals(call.ToolName, "document_plan", StringComparison.OrdinalIgnoreCase))
-            return;
-
-        documentPlanCalled = true;
-        var po = result.Output ?? string.Empty;
-        var pm = System.Text.RegularExpressions.Regex.Match(po, @"path:\s*""([^""]+)""");
-        if (pm.Success) documentPlanPath = pm.Groups[1].Value;
-        var tm = System.Text.RegularExpressions.Regex.Match(po, @"title:\s*""([^""]+)""");
-        if (tm.Success) documentPlanTitle = tm.Groups[1].Value;
-        documentPlanScaffold = ExtractDocumentPlanScaffold(po);
-
-        if (!ContainsDocumentPlanFollowUpInstruction(po))
-            return;
-
-        var toolHint = ResolveDocumentPlanFollowUpTool(po);
-        messages.Add(new ChatMessage
-        {
-            Role = "user",
-            Content =
-                "document_plan이 완료되었습니다. " +
-                "방금 생성된 골격의 [내용...] 자리와 각 섹션 내용을 실제 상세 본문으로 모두 채운 뒤 " +
-                $"{toolHint} 도구를 지금 즉시 호출하세요. " +
-                "설명만 하지 말고 실제 문서 생성 도구 호출로 바로 이어가세요."
-        });
-        EmitEvent(AgentEventType.Thinking, "", $"문서 개요 완료 · {toolHint} 실행 유도");
-    }
-
-    private static string? ExtractDocumentPlanScaffold(string output)
-    {
-        if (string.IsNullOrWhiteSpace(output))
-            return null;
-
-        var markers = new (string Start, string End)[]
-        {
-            ("--- body 시작 ---", "--- body 끝 ---"),
-            ("--- body start ---", "--- body end ---"),
-            ("<!-- body start marker -->", "<!-- body end marker -->"),
-        };
-
-        foreach (var (startMarker, endMarker) in markers)
-        {
-            var start = output.IndexOf(startMarker, StringComparison.OrdinalIgnoreCase);
-            if (start < 0)
-                continue;
-
-            var contentStart = start + startMarker.Length;
-            var end = output.IndexOf(endMarker, contentStart, StringComparison.OrdinalIgnoreCase);
-            if (end <= contentStart)
-                continue;
-
-            var scaffold = output[contentStart..end].Trim();
-            if (!string.IsNullOrWhiteSpace(scaffold))
-                return scaffold;
-        }
-
-        return null;
-    }
-
-    private static bool ContainsDocumentPlanFollowUpInstruction(string output)
-    {
-        if (string.IsNullOrWhiteSpace(output))
-            return false;
-
-        return output.Contains("즉시 실행", StringComparison.OrdinalIgnoreCase)
-               || output.Contains("immediate next step", StringComparison.OrdinalIgnoreCase)
-               || output.Contains("call html_create", StringComparison.OrdinalIgnoreCase)
-               || output.Contains("call document_assemble", StringComparison.OrdinalIgnoreCase);
-    }
-
-    private static string ResolveDocumentPlanFollowUpTool(string output)
-    {
-        if (output.Contains("document_assemble", StringComparison.OrdinalIgnoreCase))
-            return "document_assemble";
-        if (output.Contains("docx_create", StringComparison.OrdinalIgnoreCase))
-            return "docx_create";
-        if (output.Contains("markdown_create", StringComparison.OrdinalIgnoreCase))
-            return "markdown_create";
-        if (output.Contains("file_write", StringComparison.OrdinalIgnoreCase))
-            return "file_write";
-        return "html_create";
-    }
-
-    private void ApplyCodeQualityFollowUpTransition(
-        LlmService.ContentBlock call,
-        ToolResult result,
-        List<ChatMessage> messages,
-        TaskTypePolicy taskPolicy,
-        ref bool requireHighImpactCodeVerification,
-        ref string? lastModifiedCodeFilePath)
-    {
-        var highImpactCodeChange = IsHighImpactCodeModification(ActiveTab ?? "", call.ToolName, result);
-        if (ShouldInjectCodeQualityFollowUp(ActiveTab ?? "", call.ToolName, result))
-        {
-            requireHighImpactCodeVerification = highImpactCodeChange;
-            lastModifiedCodeFilePath = result.FilePath;
-            messages.Add(new ChatMessage
-            {
-                Role = "user",
-                Content = BuildCodeQualityFollowUpPrompt(
-                    call.ToolName,
-                    result,
-                    highImpactCodeChange,
-                    HasAnyBuildOrTestEvidence(messages),
-                    taskPolicy)
-            });
-            EmitEvent(AgentEventType.Thinking, "", highImpactCodeChange
-                ? "怨좎쁺??肄붾뱶 蹂€寃쎌쑝濡?李몄“ 寃€利앷낵 build/test 寃€利앹쓣 ???꾧꺽?섍쾶 ?댁뼱媛묐땲??."
-                : "肄붾뱶 蹂€寃???build/test/diff 寃€利앹쓣 ?댁뼱媛묐땲??.");
-        }
-        else if (HasCodeVerificationEvidenceAfterLastModification(messages, requireHighImpactCodeVerification))
-        {
-            requireHighImpactCodeVerification = false;
-        }
-    }
-
-    private async Task<(bool Completed, bool ConsumedExtraIteration)> TryHandleTerminalDocumentCompletionTransitionAsync(
-        LlmService.ContentBlock call,
-        ToolResult result,
-        List<LlmService.ContentBlock> toolCalls,
-        List<ChatMessage> messages,
-        Models.LlmSettings llm,
-        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy,
-        AgentContext context,
-        CancellationToken ct)
-    {
-        if (!result.Success || !IsTerminalDocumentTool(call.ToolName) || toolCalls.Count != 1)
-            return (false, false);
-
-        var verificationEnabled = executionPolicy.EnablePostToolVerification
-            && AgentTabSettingsResolver.IsPostToolVerificationEnabled(ActiveTab, llm);
-        var shouldVerify = ShouldRunPostToolVerification(
-            ActiveTab,
-            call.ToolName,
-            result.Success,
-            verificationEnabled,
-            verificationEnabled);
-        var consumedExtraIteration = false;
-        if (shouldVerify)
-        {
-            await RunPostToolVerificationAsync(messages, call.ToolName, result, context, ct);
-            consumedExtraIteration = true;
-        }
-
-        EmitEvent(AgentEventType.Complete, "", "에이전트 작업 완료");
-        return (true, consumedExtraIteration);
-    }
-
-    private async Task<bool> TryApplyPostToolVerificationTransitionAsync(
-        LlmService.ContentBlock call,
-        ToolResult result,
-        List<ChatMessage> messages,
-        Models.LlmSettings llm,
-        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy,
-        AgentContext context,
-        CancellationToken ct)
-    {
-        if (!result.Success)
-            return false;
-
-        var verificationEnabled = executionPolicy.EnablePostToolVerification
-            && AgentTabSettingsResolver.IsPostToolVerificationEnabled(ActiveTab, llm);
-        var shouldVerify = ShouldRunPostToolVerification(
-            ActiveTab,
-            call.ToolName,
-            result.Success,
-            verificationEnabled,
-            verificationEnabled);
-        if (!shouldVerify)
-            return false;
-
-        await RunPostToolVerificationAsync(messages, call.ToolName, result, context, ct);
-        return true;
-    }
-
     private async Task<(bool ShouldContinue, string? TerminalResponse)> TryHandleUserDecisionTransitionsAsync(
         LlmService.ContentBlock call,
         AgentContext context,

src/AxCopilot/Services/Agent/AgentLoopTransitions.Verification.cs

@@ -0,0 +1,233 @@
+using AxCopilot.Models;
+
+namespace AxCopilot.Services.Agent;
+
+public partial class AgentLoopService
+{
+    private void ApplyCodeQualityFollowUpTransition(
+        LlmService.ContentBlock call,
+        ToolResult result,
+        List<ChatMessage> messages,
+        TaskTypePolicy taskPolicy,
+        ref bool requireHighImpactCodeVerification,
+        ref string? lastModifiedCodeFilePath)
+    {
+        var highImpactCodeChange = IsHighImpactCodeModification(ActiveTab ?? "", call.ToolName, result);
+        if (ShouldInjectCodeQualityFollowUp(ActiveTab ?? "", call.ToolName, result))
+        {
+            requireHighImpactCodeVerification = highImpactCodeChange;
+            lastModifiedCodeFilePath = result.FilePath;
+            messages.Add(new ChatMessage
+            {
+                Role = "user",
+                Content = BuildCodeQualityFollowUpPrompt(
+                    call.ToolName,
+                    result,
+                    highImpactCodeChange,
+                    HasAnyBuildOrTestEvidence(messages),
+                    taskPolicy)
+            });
+            EmitEvent(AgentEventType.Thinking, "", highImpactCodeChange
+                ? "고영향 코드 변경으로 분류돼 참조 검증과 build/test 검증을 더 엄격하게 이어갑니다."
+                : "코드 변경 후 build/test/diff 검증을 이어갑니다.");
+        }
+        else if (HasCodeVerificationEvidenceAfterLastModification(messages, requireHighImpactCodeVerification))
+        {
+            requireHighImpactCodeVerification = false;
+        }
+    }
+
+    private bool TryApplyCodeCompletionGateTransition(
+        List<ChatMessage> messages,
+        string? textResponse,
+        TaskTypePolicy taskPolicy,
+        bool requireHighImpactCodeVerification,
+        int totalToolCalls,
+        RunState runState,
+        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
+    {
+        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase) || totalToolCalls <= 0)
+            return false;
+
+        var hasCodeVerificationEvidence = HasCodeVerificationEvidenceAfterLastModification(
+            messages,
+            requireHighImpactCodeVerification);
+        if (executionPolicy.CodeVerificationGateMaxRetries > 0
+            && !hasCodeVerificationEvidence
+            && runState.CodeVerificationGateRetry < executionPolicy.CodeVerificationGateMaxRetries)
+        {
+            runState.CodeVerificationGateRetry++;
+            if (!string.IsNullOrEmpty(textResponse))
+                messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+            messages.Add(new ChatMessage
+            {
+                Role = "user",
+                Content = requireHighImpactCodeVerification
+                    ? "[System:CodeQualityGate] 공용/핵심 코드 변경 이후 검증 근거가 부족합니다. 종료하지 말고 file_read, grep/glob, git diff, build/test까지 확인한 뒤에만 마무리하세요."
+                    : "[System:CodeQualityGate] 마지막 코드 수정 이후 build/test/file_read/diff 근거가 부족합니다. 종료하지 말고 검증 근거를 보강한 뒤에만 마무리하세요."
+            });
+            EmitEvent(AgentEventType.Thinking, "", requireHighImpactCodeVerification
+                ? "핵심 코드 변경의 검증 근거가 부족해 추가 검증을 진행합니다..."
+                : "코드 결과 검증 근거가 부족해 추가 검증을 진행합니다...");
+            return true;
+        }
+
+        if (requireHighImpactCodeVerification
+            && executionPolicy.HighImpactBuildTestGateMaxRetries > 0
+            && !HasSuccessfulBuildAndTestAfterLastModification(messages)
+            && runState.HighImpactBuildTestGateRetry < executionPolicy.HighImpactBuildTestGateMaxRetries)
+        {
+            runState.HighImpactBuildTestGateRetry++;
+            if (!string.IsNullOrEmpty(textResponse))
+                messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+            messages.Add(new ChatMessage
+            {
+                Role = "user",
+                Content = "[System:HighImpactBuildTestGate] 핵심 코드 변경입니다. 종료하지 말고 build_run과 test_loop를 모두 실행해 성공 근거를 확보한 뒤에만 마무리하세요."
+            });
+            EmitEvent(AgentEventType.Thinking, "", "핵심 변경이라 build+test 성공 근거를 모두 확보할 때까지 진행합니다...");
+            return true;
+        }
+
+        if (executionPolicy.FinalReportGateMaxRetries > 0
+            && !HasSufficientFinalReportEvidence(textResponse, taskPolicy, requireHighImpactCodeVerification, messages)
+            && runState.FinalReportGateRetry < executionPolicy.FinalReportGateMaxRetries)
+        {
+            runState.FinalReportGateRetry++;
+            if (!string.IsNullOrEmpty(textResponse))
+                messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+            messages.Add(new ChatMessage
+            {
+                Role = "user",
+                Content = BuildFinalReportQualityPrompt(taskPolicy, requireHighImpactCodeVerification)
+            });
+            EmitEvent(AgentEventType.Thinking, "", "최종 보고에 변경·검증·리스크 요약이 부족해 한 번 더 정리합니다...");
+            return true;
+        }
+
+        return false;
+    }
+
+    private bool TryApplyCodeDiffEvidenceGateTransition(
+        List<ChatMessage> messages,
+        string? textResponse,
+        RunState runState,
+        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
+    {
+        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase))
+            return false;
+
+        if (executionPolicy.CodeDiffGateMaxRetries <= 0 || runState.CodeDiffGateRetry >= executionPolicy.CodeDiffGateMaxRetries)
+            return false;
+
+        if (HasDiffEvidenceAfterLastModification(messages))
+            return false;
+
+        runState.CodeDiffGateRetry++;
+        if (!string.IsNullOrEmpty(textResponse))
+            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+        messages.Add(new ChatMessage
+        {
+            Role = "user",
+            Content = "[System:CodeDiffGate] 코드 변경 이후 diff 근거가 부족합니다. git_tool 도구로 변경 파일과 핵심 diff를 먼저 확인하고 요약하세요. 지금 즉시 git_tool 도구를 호출하세요."
+        });
+        EmitEvent(AgentEventType.Thinking, "", "코드 diff 근거가 부족해 git diff 검증을 추가합니다...");
+        return true;
+    }
+
+    private bool TryApplyRecentExecutionEvidenceGateTransition(
+        List<ChatMessage> messages,
+        string? textResponse,
+        TaskTypePolicy taskPolicy,
+        RunState runState,
+        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
+    {
+        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase))
+            return false;
+
+        if (executionPolicy.RecentExecutionGateMaxRetries <= 0 || runState.RecentExecutionGateRetry >= executionPolicy.RecentExecutionGateMaxRetries)
+            return false;
+
+        if (!HasAnyBuildOrTestEvidence(messages))
+            return false;
+
+        if (HasBuildOrTestEvidenceAfterLastModification(messages))
+            return false;
+
+        runState.RecentExecutionGateRetry++;
+        if (!string.IsNullOrEmpty(textResponse))
+            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+        messages.Add(new ChatMessage
+        {
+            Role = "user",
+            Content = BuildRecentExecutionEvidencePrompt(taskPolicy)
+        });
+        EmitEvent(AgentEventType.Thinking, "", "최근 수정 이후 실행 근거가 부족해 build/test 재검증을 수행합니다...");
+        return true;
+    }
+
+    private bool TryApplyExecutionSuccessGateTransition(
+        List<ChatMessage> messages,
+        string? textResponse,
+        TaskTypePolicy taskPolicy,
+        RunState runState,
+        ModelExecutionProfileCatalog.ExecutionPolicy executionPolicy)
+    {
+        if (!string.Equals(ActiveTab, "Code", StringComparison.OrdinalIgnoreCase))
+            return false;
+
+        if (executionPolicy.ExecutionSuccessGateMaxRetries <= 0 || runState.ExecutionSuccessGateRetry >= executionPolicy.ExecutionSuccessGateMaxRetries)
+            return false;
+
+        if (!HasAnyBuildOrTestAttempt(messages))
+            return false;
+
+        if (HasAnyBuildOrTestEvidence(messages))
+            return false;
+
+        runState.ExecutionSuccessGateRetry++;
+        if (!string.IsNullOrEmpty(textResponse))
+            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+        messages.Add(new ChatMessage
+        {
+            Role = "user",
+            Content = BuildExecutionSuccessGatePrompt(taskPolicy)
+        });
+        EmitEvent(AgentEventType.Thinking, "", "실패한 실행 근거만 있어 build/test 성공 결과를 다시 검증합니다...");
+        return true;
+    }
+
+    private bool TryApplyTerminalEvidenceGateTransition(
+        List<ChatMessage> messages,
+        string? textResponse,
+        TaskTypePolicy taskPolicy,
+        string userQuery,
+        int totalToolCalls,
+        string? lastArtifactFilePath,
+        RunState runState,
+        int retryMax)
+    {
+        if (totalToolCalls <= 0)
+            return false;
+
+        if (ShouldSkipTerminalEvidenceGateForAnalysisQuery(userQuery, taskPolicy))
+            return false;
+
+        if (runState.TerminalEvidenceGateRetry >= retryMax)
+            return false;
+
+        if (HasTerminalProgressEvidence(taskPolicy, messages, lastArtifactFilePath))
+            return false;
+
+        runState.TerminalEvidenceGateRetry++;
+        if (!string.IsNullOrEmpty(textResponse))
+            messages.Add(new ChatMessage { Role = "assistant", Content = textResponse });
+        messages.Add(new ChatMessage
+        {
+            Role = "user",
+            Content = BuildTerminalEvidenceGatePrompt(taskPolicy, lastArtifactFilePath)
+        });
+        EmitEvent(AgentEventType.Thinking, "", $"종료 전 실행 증거가 부족해 보강 단계를 진행합니다 ({runState.TerminalEvidenceGateRetry}/{retryMax})");
+        return true;
+    }
+}

src/AxCopilot/Services/AgentPerformanceLogService.cs

@@ -0,0 +1,72 @@
+using System.Text;
+using System.Text.Json;
+using System.IO;
+
+namespace AxCopilot.Services;
+
+public static class AgentPerformanceLogService
+{
+    private static readonly string PerfDir;
+    private static readonly object _lock = new();
+    private static readonly JsonSerializerOptions _jsonOptions = new()
+    {
+        WriteIndented = false,
+        Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
+    };
+
+    static AgentPerformanceLogService()
+    {
+        PerfDir = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+            "AxCopilot",
+            "perf");
+        try { Directory.CreateDirectory(PerfDir); } catch { }
+    }
+
+    public static void LogMetric(
+        string area,
+        string name,
+        string conversationId,
+        string tab,
+        long durationMs,
+        object? detail = null)
+    {
+        try
+        {
+            var fileName = $"performance-{DateTime.Now:yyyy-MM-dd}.json";
+            var filePath = Path.Combine(PerfDir, fileName);
+            var json = JsonSerializer.Serialize(new AgentPerformanceEntry
+            {
+                Timestamp = DateTime.Now,
+                Area = area,
+                Name = name,
+                ConversationId = conversationId ?? "",
+                Tab = tab ?? "",
+                DurationMs = durationMs,
+                Detail = detail == null ? "" : JsonSerializer.Serialize(detail, _jsonOptions),
+            }, _jsonOptions);
+
+            lock (_lock)
+            {
+                File.AppendAllText(filePath, json + Environment.NewLine, Encoding.UTF8);
+            }
+        }
+        catch
+        {
+            // 성능 로그 실패는 런타임에 영향 주지 않음
+        }
+    }
+
+    public static string GetPerformanceFolder() => PerfDir;
+}
+
+public sealed class AgentPerformanceEntry
+{
+    public DateTime Timestamp { get; init; }
+    public string Area { get; init; } = "";
+    public string Name { get; init; } = "";
+    public string ConversationId { get; init; } = "";
+    public string Tab { get; init; } = "";
+    public long DurationMs { get; init; }
+    public string Detail { get; init; } = "";
+}

src/AxCopilot/Views/ChatWindow.TranscriptRendering.cs

@@ -1,5 +1,7 @@
+using System.Diagnostics;
 using System.Windows.Threading;
 using AxCopilot.Models;
+using AxCopilot.Services;
 
 namespace AxCopilot.Views;
 
@@ -18,6 +20,7 @@ public partial class ChatWindow
 
     private void RenderMessages(bool preserveViewport = false)
     {
+        var renderStopwatch = Stopwatch.StartNew();
         var previousScrollableHeight = GetTranscriptScrollableHeight();
         var previousVerticalOffset = GetTranscriptVerticalOffset();
 
@@ -62,10 +65,32 @@ public partial class ChatWindow
 
         if (!TryApplyIncrementalTranscriptRender(renderPlan))
             ApplyFullTranscriptRender(renderPlan);
+        PruneTranscriptElementCache(renderPlan.NewKeys);
 
         _lastRenderedMessageCount = visibleMessages.Count;
         _lastRenderedEventCount = visibleEvents.Count;
         _lastRenderedShowHistory = renderPlan.ShowHistory;
+        renderStopwatch.Stop();
+        if (renderStopwatch.ElapsedMilliseconds >= 24 || _isStreaming)
+        {
+            AgentPerformanceLogService.LogMetric(
+                "transcript",
+                "render_messages",
+                conv.Id,
+                _activeTab ?? "",
+                renderStopwatch.ElapsedMilliseconds,
+                new
+                {
+                    preserveViewport,
+                    streaming = _isStreaming,
+                    lightweight = IsLightweightLiveProgressMode(),
+                    visibleMessages = visibleMessages.Count,
+                    visibleEvents = visibleEvents.Count,
+                    renderedItems = renderPlan.NewKeys.Count,
+                    hiddenCount = renderPlan.HiddenCount,
+                    transcriptElements = GetTranscriptElementCount(),
+                });
+        }
 
         if (!preserveViewport)
         {

src/AxCopilot/Views/ChatWindow.TranscriptVirtualization.cs

@@ -0,0 +1,25 @@
+using System.Linq;
+
+namespace AxCopilot.Views;
+
+public partial class ChatWindow
+{
+    private const int TranscriptCacheRetentionCount = 240;
+
+    private void PruneTranscriptElementCache(IReadOnlyCollection<string> visibleKeys)
+    {
+        if (_elementCache.Count <= TranscriptCacheRetentionCount)
+            return;
+
+        var keep = new HashSet<string>(visibleKeys, StringComparer.Ordinal);
+        foreach (var key in _lastRenderedTimelineKeys.TakeLast(Math.Min(TranscriptCacheRetentionCount, _lastRenderedTimelineKeys.Count)))
+            keep.Add(key);
+
+        var removable = _elementCache.Keys
+            .Where(key => !keep.Contains(key))
+            .ToList();
+
+        foreach (var key in removable)
+            _elementCache.Remove(key);
+    }
+}

src/AxCopilot/Views/ChatWindow.xaml

@@ -1366,9 +1366,12 @@
                          ScrollViewer.VerticalScrollBarVisibility="Auto"
                          ScrollViewer.HorizontalScrollBarVisibility="Disabled"
                          ScrollViewer.CanContentScroll="True"
+                         ScrollViewer.IsDeferredScrollingEnabled="True"
                          VirtualizingPanel.IsVirtualizing="True"
                          VirtualizingPanel.VirtualizationMode="Recycling"
                          VirtualizingPanel.ScrollUnit="Pixel"
+                         VirtualizingPanel.CacheLength="2"
+                         VirtualizingPanel.CacheLengthUnit="Item"
                          UseLayoutRounding="True">
                     <ListBox.ItemsPanel>
                         <ItemsPanelTemplate>