compact 뒤 첨부 참조가 이어지도록 요약/경계 메시지를 보강

- ContextCondenser가 오래된 메시지 구간의 첨부 파일 이름과 이미지 개수를 수집해 microcompact boundary와 요약 메시지에 함께 기록
- 요약 메시지에 AttachedFiles를 보존해 compact 이후 query view에서도 파일 참조 continuity가 유지되도록 조정
- README와 DEVELOPMENT 문서에 2026-04-12 22:36 (KST) 기준 작업 이력 반영
- 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/Services/Agent/ContextCondenser.cs

@@ -54,6 +54,12 @@ public static class ContextCondenser
         public int PreservedToolPairs { get; init; }
     }
 
+    private sealed class CompactionAttachmentSummary
+    {
+        public required List<string> AttachedFiles { get; init; }
+        public int ImageCount { get; init; }
+    }
+
     /// <summary>모델별 입력 토큰 한도 (대략).</summary>
     private static int GetModelInputLimit(string service, string model)
     {
@@ -703,17 +709,7 @@ public static class ContextCondenser
             !(m.Content ?? "").StartsWith("{\"_tool_use_blocks\"", StringComparison.Ordinal) &&
             m.MetaKind == null);
 
-        var attachedFiles = group
-            .SelectMany(m => m.AttachedFiles ?? Enumerable.Empty<string>())
-            .Distinct(StringComparer.OrdinalIgnoreCase)
-            .Select(path =>
-            {
-                try { return System.IO.Path.GetFileName(path); }
-                catch { return path; }
-            })
-            .Where(name => !string.IsNullOrWhiteSpace(name))
-            .Take(4)
-            .ToList();
+        var attachmentSummary = CollectCompactionAttachmentSummary(group, 4);
 
         var lines = new List<string>
         {
@@ -724,7 +720,8 @@ public static class ContextCondenser
         if (toolCalls > 0) lines.Add($"- 도구 호출 {toolCalls}건 정리");
         if (metaEvents > 0) lines.Add($"- 실행 메타/로그 {metaEvents}건 정리");
         if (longTexts > 0) lines.Add($"- 긴 설명/출력 {longTexts}건 축약");
-        if (attachedFiles.Count > 0) lines.Add($"- 관련 파일: {string.Join(", ", attachedFiles)}");
+        if (attachmentSummary.AttachedFiles.Count > 0) lines.Add($"- 관련 파일: {string.Join(", ", attachmentSummary.AttachedFiles)}");
+        if (attachmentSummary.ImageCount > 0) lines.Add($"- 관련 이미지: {attachmentSummary.ImageCount}개");
 
         return new ChatMessage
         {
@@ -733,6 +730,7 @@ public static class ContextCondenser
             Timestamp = group.Last().Timestamp,
             MetaKind = "microcompact_boundary",
             MetaRunId = group.Last().MetaRunId,
+            AttachedFiles = attachmentSummary.AttachedFiles.Count > 0 ? attachmentSummary.AttachedFiles : null,
         };
     }
 
@@ -747,6 +745,7 @@ public static class ContextCondenser
         var systemMsg = window.SystemMessage;
         var oldMessages = window.OldMessages;
         var recentMessages = window.RecentMessages;
+        var attachmentSummary = CollectCompactionAttachmentSummary(oldMessages, 6);
 
         if (oldMessages.Count < 3) return false;
 
@@ -787,8 +786,9 @@ public static class ContextCondenser
             messages.Add(new ChatMessage
             {
                 Role = "user",
-                Content = $"[이전 대화 요약 — {oldMessages.Count}개 메시지 압축]\n{summary}",
+                Content = BuildSummaryMessageContent(oldMessages.Count, summary, attachmentSummary),
                 Timestamp = DateTime.Now,
+                AttachedFiles = attachmentSummary.AttachedFiles.Count > 0 ? attachmentSummary.AttachedFiles : null,
             });
             messages.Add(new ChatMessage
             {
@@ -806,4 +806,42 @@ public static class ContextCondenser
             return false;
         }
     }
+
+    private static CompactionAttachmentSummary CollectCompactionAttachmentSummary(IEnumerable<ChatMessage> messages, int maxFiles)
+    {
+        var attachedFiles = messages
+            .SelectMany(m => m.AttachedFiles ?? Enumerable.Empty<string>())
+            .Distinct(StringComparer.OrdinalIgnoreCase)
+            .Select(path =>
+            {
+                try { return System.IO.Path.GetFileName(path); }
+                catch { return path; }
+            })
+            .Where(name => !string.IsNullOrWhiteSpace(name))
+            .Take(Math.Max(1, maxFiles))
+            .ToList();
+
+        var imageCount = messages.Sum(m => m.Images?.Count ?? 0);
+        return new CompactionAttachmentSummary
+        {
+            AttachedFiles = attachedFiles,
+            ImageCount = imageCount,
+        };
+    }
+
+    private static string BuildSummaryMessageContent(int oldMessageCount, string summary, CompactionAttachmentSummary attachmentSummary)
+    {
+        var lines = new List<string>
+        {
+            $"[이전 대화 요약 — {oldMessageCount}개 메시지 압축]",
+            summary.Trim()
+        };
+
+        if (attachmentSummary.AttachedFiles.Count > 0)
+            lines.Add($"참고 파일: {string.Join(", ", attachmentSummary.AttachedFiles)}");
+        if (attachmentSummary.ImageCount > 0)
+            lines.Add($"참고 이미지: {attachmentSummary.ImageCount}개");
+
+        return string.Join("\n", lines.Where(x => !string.IsNullOrWhiteSpace(x)));
+    }
 }