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

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)
     {