컨텍스트 압축 이력 재노출과 compact 비교 기반 보강

- AX Agent 하단 컨텍스트 카드 툴팁에 최근 압축 시각, 자동/수동 여부, 압축 전후 토큰, 절감량을 다시 볼 수 있는 compact 이력을 추가함
- 수동 /compact와 전송 전 자동 컨텍스트 압축이 모두 같은 compaction 통계 기록 경로를 사용하도록 정리해 결과를 이후 UI에서도 확인할 수 있게 보강함
- README와 docs/DEVELOPMENT.md에 2026-04-04 23:28 (KST) 기준 이력을 반영함
- 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.xaml.cs

@@ -95,6 +95,10 @@ public partial class ChatWindow : Window
     private StackPanel? _selectedMessageActionBar;
     private Border? _selectedMessageBorder;
     private bool _isRefreshingFromSettings;
+    private int? _lastCompactionBeforeTokens;
+    private int? _lastCompactionAfterTokens;
+    private DateTime? _lastCompactionAt;
+    private bool _lastCompactionWasAutomatic;
     private void ApplyQuickActionVisual(Button button, bool active, string activeBg, string activeFg)
     {
         if (button?.Content is not string text)
@@ -6507,6 +6511,7 @@ public partial class ChatWindow : Window
             true,
             CancellationToken.None);
         var afterTokens = Services.TokenEstimator.EstimateMessages(working);
+        RecordCompactionStats(beforeTokens, afterTokens, wasAutomatic: false);
 
         if (condensed)
         {
@@ -6543,6 +6548,7 @@ public partial class ChatWindow : Window
         if (StatusTokens != null)
             StatusTokens.Text = $"컨텍스트 {Services.TokenEstimator.Format(beforeTokens)} → {Services.TokenEstimator.Format(afterTokens)}";
         SetStatus(condensed ? "컨텍스트 압축 완료" : "압축할 컨텍스트 없음", spinning: false);
+        RefreshContextUsageVisual();
         RefreshConversationList();
         UpdateTaskSummaryIndicators();
     }
@@ -8075,6 +8081,7 @@ public partial class ChatWindow : Window
             // ── 전송 전 컨텍스트 사전 압축 ──
             {
                 var llm = _settings.Settings.Llm;
+                var beforeCompactTokens = Services.TokenEstimator.EstimateMessages(sendMessages);
                 var condensed = await ContextCondenser.CondenseIfNeededAsync(
                     sendMessages,
                     _llm,
@@ -8084,7 +8091,12 @@ public partial class ChatWindow : Window
                     false,
                     _streamCts!.Token);
                 if (condensed)
+                {
+                    var afterCompactTokens = Services.TokenEstimator.EstimateMessages(sendMessages);
+                    RecordCompactionStats(beforeCompactTokens, afterCompactTokens, wasAutomatic: true);
                     SetStatus("컨텍스트를 사전 정리했습니다", spinning: true);
+                    RefreshContextUsageVisual();
+                }
             }
 
             // ── 자동 모델 라우팅 ──
@@ -16481,12 +16493,20 @@ private static (string icon, string label, string bgHex, string fgHex) GetDecisi
         TokenUsageSummaryText.Text = $"컨텍스트 {percentText}";
         TokenUsageHintText.Text = $"{Services.TokenEstimator.Format(currentTokens)} / {Services.TokenEstimator.Format(maxContextTokens)}";
         CompactNowLabel.Text = compactLabel;
+        var compactHistory = _lastCompactionAt.HasValue && _lastCompactionBeforeTokens.HasValue && _lastCompactionAfterTokens.HasValue
+            ? $"\n최근 압축: {(_lastCompactionWasAutomatic ? "자동" : "수동")} · {_lastCompactionAt.Value:HH:mm:ss}\n" +
+              $"절감: {_lastCompactionBeforeTokens.Value:N0} → {_lastCompactionAfterTokens.Value:N0} tokens " +
+              $"(-{Math.Max(0, _lastCompactionBeforeTokens.Value - _lastCompactionAfterTokens.Value):N0}, " +
+              $"{Services.TokenEstimator.Format(_lastCompactionBeforeTokens.Value)} → {Services.TokenEstimator.Format(_lastCompactionAfterTokens.Value)})"
+            : "";
+
         TokenUsageCard.ToolTip =
             $"상태: {summary}\n" +
             $"사용량: {currentTokens:N0} / {maxContextTokens:N0} tokens ({percentText})\n" +
             $"간단 표기: {Services.TokenEstimator.Format(currentTokens)} / {Services.TokenEstimator.Format(maxContextTokens)}\n" +
             $"자동 압축 시작: {triggerPercent}%\n" +
-            $"현재 입력 초안 포함";
+            $"현재 입력 초안 포함" +
+            compactHistory;
 
         UpdateCircularUsageArc(TokenUsageArc, usageRatio, 18, 18, 14);
         PositionThresholdMarker(TokenUsageThresholdMarker, triggerRatio, 18, 18, 14, 3);
@@ -16535,6 +16555,14 @@ private static (string icon, string label, string bgHex, string fgHex) GetDecisi
             centerY + radius * Math.Sin(radians));
     }
 
+    private void RecordCompactionStats(int beforeTokens, int afterTokens, bool wasAutomatic)
+    {
+        _lastCompactionBeforeTokens = Math.Max(0, beforeTokens);
+        _lastCompactionAfterTokens = Math.Max(0, afterTokens);
+        _lastCompactionAt = DateTime.Now;
+        _lastCompactionWasAutomatic = wasAutomatic;
+    }
+
     private void ScheduleGitBranchRefresh(int delayMs = 400)
     {
         if (BtnGitBranch == null)