에이전트 루프 반복 준비 단계와 tool_result preview 복원 경로를 안정화한다

- AgentLoopIterationPreparationService를 추가해 queued command 투영, tool_result 대기 요약, query view 생성 책임을 AgentLoopService.RunAsync의 반복 진입부에서 분리함
- AgentMessageInvariantHelper의 preview 스냅샷을 explicit id/fingerprint와 synthetic id로 나눠 저장된 preview 우선, fingerprint 재바인딩 차선, synthetic preview 마지막 순서로 복원하도록 정리함
- AgentToolResultBudget이 source query view 기준 snapshot을 먼저 사용하도록 바꿔 source preview가 local synthetic preview에 가려지지 않게 하고 첫 축약 결과도 source message에 다시 저장함
- AgentToolResultBudgetTests와 AgentLoopIterationPreparationServiceTests를 추가/확장해 같은 tool_result의 장기 세션 재사용과 반복 준비 단계 분리를 회귀로 고정함
- README.md와 docs/DEVELOPMENT.md에 2026-04-15 10:34 (KST) 기준 작업 이력과 검증 명령을 반영함

검증 결과
- dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify_loop_pipeline\\ -p:IntermediateOutputPath=obj\\verify_loop_pipeline\\ : 경고 0 / 오류 0
- dotnet test src/AxCopilot.Tests/AxCopilot.Tests.csproj -c Release -v minimal --filter AgentQueuedCommandProjectorTests|AgentLoopIterationPreparationServiceTests|AgentMessageInvariantHelperTests|AgentToolResultBudgetTests|AgentQueryContextBuilderTests|ChatStorageServiceTests -p:OutputPath=bin\\verify_loop_pipeline_tests\\ -p:IntermediateOutputPath=obj\\verify_loop_pipeline_tests\\ : 통과 14

README.md

@@ -7,6 +7,13 @@ Windows 전용 시맨틱 런처 & 워크스페이스 매니저
 개발 참고: Claw Code 동등성 작업 추적 문서  
 `docs/claw-code-parity-plan.md`
 
+- 업데이트: 2026-04-15 10:34 (KST)
+- AX Agent 루프의 반복 준비 단계를 분리했습니다. [AgentLoopIterationPreparationService.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopIterationPreparationService.cs)가 queued command 투영, tool result 대기 요약, query view 생성 책임을 묶어 [AgentLoopService.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentLoopService.cs)의 반복 진입부를 더 가볍게 정리합니다.
+- 긴 세션과 분기 대화에서 `tool_result` preview가 더 안정적으로 유지되도록 [AgentMessageInvariantHelper.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentMessageInvariantHelper.cs)와 [AgentToolResultBudget.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/AgentToolResultBudget.cs)를 보강했습니다. 명시적 preview, fingerprint 재바인딩, synthetic preview의 우선순위를 분리해 저장/재개 후에도 사람이 보던 축약 결과를 우선 재사용합니다.
+- 테스트: [AgentLoopIterationPreparationServiceTests.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot.Tests/Services/AgentLoopIterationPreparationServiceTests.cs), [AgentMessageInvariantHelperTests.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot.Tests/Services/AgentMessageInvariantHelperTests.cs), [AgentToolResultBudgetTests.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot.Tests/Services/AgentToolResultBudgetTests.cs)
+- 검증: `dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify_loop_pipeline\\ -p:IntermediateOutputPath=obj\\verify_loop_pipeline\\` 경고 0 / 오류 0
+- 검증: `dotnet test src/AxCopilot.Tests/AxCopilot.Tests.csproj -c Release -v minimal --filter "AgentQueuedCommandProjectorTests|AgentLoopIterationPreparationServiceTests|AgentMessageInvariantHelperTests|AgentToolResultBudgetTests|AgentQueryContextBuilderTests|ChatStorageServiceTests" -p:OutputPath=bin\\verify_loop_pipeline_tests\\ -p:IntermediateOutputPath=obj\\verify_loop_pipeline_tests\\` 통과 14
+
 - 업데이트: 2026-04-14 21:25 (KST)
 - 업데이트: 2026-04-14 22:52 (KST)
 - 문서 포맷 고도화를 한 단계 더 진행했습니다. [ExcelSkill.cs](/E:/AX%20Copilot%20-%20Codex/src/AxCopilot/Services/Agent/ExcelSkill.cs)에 `conditional_formats`를 추가해 색상 스케일과 데이터 바 조건부서식을 네이티브 OpenXML로 생성하고, 품질 리뷰에도 반영되도록 했습니다.

docs/DEVELOPMENT.md

@@ -17,6 +17,14 @@
 - 검증: `dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify_next_doc_ppt\\ -p:IntermediateOutputPath=obj\\verify_next_doc_ppt\\` 경고 0 / 오류 0
 - 검증: `dotnet test src/AxCopilot.Tests/AxCopilot.Tests.csproj -c Release -v minimal --filter "ArtifactQualityReviewServiceTests|ExcelSkillDataValidationTests|ExcelSkillConditionalFormattingTests|ExcelSkillExecutiveSummaryLinkTests|ExcelSkillSummarySheetTests|DocxSkillTemplateFeaturesTests|DocxSkillStyleMapTests|HtmlSkillConsultingSectionsTests|HtmlSkillPrintFrameTests|DocumentAssemblerDocxFeaturesTests|PptxSkillConsultingDeckTests|PptxSkillAutoRepairTests|PptxSkillTemplatePackTests" -p:OutputPath=bin\\verify_next_doc_ppt_tests\\ -p:IntermediateOutputPath=obj\\verify_next_doc_ppt_tests\\` 통과 15
 
+업데이트: 2026-04-15 10:34 (KST)
+- Agent loop 반복 진입부를 분리했습니다. `src/AxCopilot/Services/Agent/AgentLoopIterationPreparationService.cs`를 추가해 queued command 투영, tool_result 대기 요약 생성, `AgentQueryContextBuilder.Build()` 호출을 공통 준비 단계로 묶고, `AgentLoopService.RunAsync()`는 orchestration에 더 집중하도록 정리했습니다.
+- `src/AxCopilot/Services/Agent/AgentMessageInvariantHelper.cs`는 tool result preview 스냅샷을 `ExplicitByToolResultId`, `ExplicitByFingerprint`, `SyntheticByToolResultId`로 분리합니다. 저장된 preview가 있으면 그것을 우선 쓰고, 다른 세션에서 `tool_use_id`가 바뀐 경우에는 fingerprint 재바인딩을 통해 안정적인 preview를 복원하며, 마지막에만 synthetic preview를 사용합니다.
+- `src/AxCopilot/Services/Agent/AgentToolResultBudget.cs`는 source query view가 있을 때 source 기준 snapshot을 먼저 만들고, query view에는 그 결과를 재사용하도록 순서를 조정했습니다. 이로써 source 쪽 explicit preview가 local synthetic preview에 가려지지 않고, 첫 축약 결과도 source message에 다시 저장됩니다.
+- 테스트: `src/AxCopilot.Tests/Services/AgentLoopIterationPreparationServiceTests.cs`, `src/AxCopilot.Tests/Services/AgentMessageInvariantHelperTests.cs`, `src/AxCopilot.Tests/Services/AgentToolResultBudgetTests.cs`
+- 검증: `dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify_loop_pipeline\\ -p:IntermediateOutputPath=obj\\verify_loop_pipeline\\` 경고 0 / 오류 0
+- 검증: `dotnet test src/AxCopilot.Tests/AxCopilot.Tests.csproj -c Release -v minimal --filter "AgentQueuedCommandProjectorTests|AgentLoopIterationPreparationServiceTests|AgentMessageInvariantHelperTests|AgentToolResultBudgetTests|AgentQueryContextBuilderTests|ChatStorageServiceTests" -p:OutputPath=bin\\verify_loop_pipeline_tests\\ -p:IntermediateOutputPath=obj\\verify_loop_pipeline_tests\\` 통과 14
+
 업데이트: 2026-04-14 19:50 (KST)
 - Agent loop/queue/context 품질을 보강했습니다. `src/AxCopilot/Services/Agent/AgentCommandQueue.cs`로 실행 중 추가 입력을 우선순위와 interrupt 여부까지 포함해 관리하고, `AgentLoopService`는 이를 안전하게 반영합니다.
 - `AgentToolResultBudget`, `AgentQueryContextBuilder`, `ChatModels`는 tool result preview를 메시지에 캐시해 긴 세션과 재질문에서도 같은 축약 결과를 재사용하도록 정리했습니다.

src/AxCopilot.Tests/Services/AgentLoopIterationPreparationServiceTests.cs

@@ -0,0 +1,61 @@
+using AxCopilot.Models;
+using AxCopilot.Services.Agent;
+using FluentAssertions;
+using Xunit;
+
+namespace AxCopilot.Tests.Services;
+
+public class AgentLoopIterationPreparationServiceTests
+{
+    [Fact]
+    public void Prepare_ShouldProjectQueuedCommandsAndBuildUpdatedQueryView()
+    {
+        var messages = new List<ChatMessage>
+        {
+            new()
+            {
+                MsgId = "assistant-1",
+                Role = "assistant",
+                Content = "existing assistant message"
+            }
+        };
+
+        var queue = new AgentCommandQueue();
+        queue.EnqueueSteering("focus on the changed files", priority: "now", requestInterrupt: true);
+        queue.EnqueueNotification("low priority note", priority: "later");
+
+        var result = AgentLoopIterationPreparationService.Prepare(
+            messages,
+            queue,
+            lastToolResultAtUtc: null,
+            lastToolResultToolName: null,
+            utcNow: DateTime.UtcNow);
+
+        messages.Should().Contain(message =>
+            message.MetaKind == "queued_input_interrupt" &&
+            message.Role == "system");
+        messages.Should().Contain(message =>
+            message.MetaKind == "queued_steering" &&
+            message.Role == "user" &&
+            message.Content == "focus on the changed files");
+        result.QueueProjection.Events.Should().Contain(evt =>
+            evt.Type == AgentEventType.Thinking &&
+            evt.Summary.Contains("Deferred 1 lower-priority", StringComparison.OrdinalIgnoreCase));
+        result.QueryView.Messages.Should().Contain(message =>
+            message.MetaKind == "queued_steering" &&
+            message.Role == "user");
+    }
+
+    [Fact]
+    public void BuildToolResultWaitSummary_ShouldFormatToolNameAndElapsedMilliseconds()
+    {
+        var utcNow = DateTime.UtcNow;
+        var waitSummary = AgentLoopIterationPreparationService.BuildToolResultWaitSummary(
+            utcNow.AddMilliseconds(-1250),
+            "file_read",
+            utcNow);
+
+        waitSummary.Should().StartWith("file_read:");
+        waitSummary.Should().Contain("ms");
+    }
+}

src/AxCopilot.Tests/Services/AgentToolResultBudgetTests.cs

@@ -131,4 +131,49 @@ public class AgentToolResultBudgetTests
         result.ReusedPreviewCount.Should().BeGreaterThan(0);
         queryView[1].QueryPreviewContent.Should().Be(queryView[0].QueryPreviewContent);
     }
+
+    [Fact]
+    public void Apply_ShouldReuseFingerprintPreviewFromSourceMessages_WhenToolUseIdChangesAcrossSessions()
+    {
+        var longContent = new string('D', 1700);
+        var sourceMessages = new List<ChatMessage>
+        {
+            new()
+            {
+                MsgId = "source-tool",
+                Role = "user",
+                Content = $$"""{"type":"tool_result","tool_use_id":"call-original","tool_name":"file_read","content":"{{longContent}}"}""",
+                QueryPreviewContent = """{"type":"tool_result","tool_use_id":"call-original","tool_name":"file_read","content":"preview-fingerprint"}"""
+            },
+            new()
+            {
+                MsgId = "tail-1",
+                Role = "assistant",
+                Content = "recent tail"
+            }
+        };
+
+        var queryView = new List<ChatMessage>
+        {
+            new()
+            {
+                MsgId = "rebuilt-tool",
+                Role = "user",
+                Content = $$"""{"type":"tool_result","tool_use_id":"call-replayed","tool_name":"file_read","content":"{{longContent}}"}"""
+            },
+            new()
+            {
+                MsgId = "tail-2",
+                Role = "assistant",
+                Content = "recent tail"
+            }
+        };
+
+        var result = AgentToolResultBudget.Apply(queryView, protectedRecentNonSystemMessages: 1, sourceMessages: sourceMessages);
+
+        result.ReusedPreviewCount.Should().Be(1);
+        queryView[0].Content.Should().Contain("call-replayed");
+        queryView[0].Content.Should().Contain("preview-fingerprint");
+        queryView[0].Content.Should().NotContain("call-original");
+    }
 }

src/AxCopilot/Services/Agent/AgentLoopIterationPreparationService.cs

@@ -0,0 +1,59 @@
+using AxCopilot.Models;
+
+namespace AxCopilot.Services.Agent;
+
+internal sealed record AgentLoopIterationPreparationResult(
+    AgentQueuedCommandProjectionResult QueueProjection,
+    AgentQueryContextWindowResult QueryView,
+    string? ToolResultWaitSummary);
+
+/// <summary>
+/// RunAsync 반복 시작 시점의 공통 준비 작업을 묶습니다.
+/// queued command 투영, tool_result 대기 진단, query view 생성 책임을 분리해
+/// AgentLoopService 본체를 orchestration 중심으로 유지합니다.
+/// </summary>
+internal static class AgentLoopIterationPreparationService
+{
+    public static AgentLoopIterationPreparationResult Prepare(
+        List<ChatMessage> messages,
+        AgentCommandQueue pendingCommands,
+        DateTime? lastToolResultAtUtc,
+        string? lastToolResultToolName,
+        DateTime utcNow)
+    {
+        var queueProjection = ProjectQueuedCommands(messages, pendingCommands);
+        var queryView = AgentQueryContextBuilder.Build(messages);
+        var waitSummary = BuildToolResultWaitSummary(lastToolResultAtUtc, lastToolResultToolName, utcNow);
+
+        return new AgentLoopIterationPreparationResult(queueProjection, queryView, waitSummary);
+    }
+
+    public static string? BuildToolResultWaitSummary(
+        DateTime? lastToolResultAtUtc,
+        string? lastToolResultToolName,
+        DateTime utcNow)
+    {
+        if (lastToolResultAtUtc is not { } toolResultAt)
+            return null;
+
+        var waitMs = Math.Max(0, (long)(utcNow - toolResultAt).TotalMilliseconds);
+        return $"{lastToolResultToolName ?? "unknown"}:{waitMs}ms";
+    }
+
+    private static AgentQueuedCommandProjectionResult ProjectQueuedCommands(
+        List<ChatMessage> messages,
+        AgentCommandQueue pendingCommands)
+    {
+        var queuedSnapshot = pendingCommands.Snapshot();
+        if (queuedSnapshot.Count == 0)
+            return new AgentQueuedCommandProjectionResult([], []);
+
+        var drained = pendingCommands.DequeuePriorityBatch();
+        if (drained.Count == 0)
+            return new AgentQueuedCommandProjectionResult([], []);
+
+        var projection = AgentQueuedCommandProjector.Project(drained, queuedSnapshot.Count - drained.Count);
+        messages.AddRange(projection.Messages);
+        return projection;
+    }
+}

src/AxCopilot/Services/Agent/AgentLoopService.cs

@@ -451,23 +451,28 @@ public partial class AgentLoopService
                     }
                 }
 
-                if (lastToolResultAtUtc is { } toolResultAt)
+                var iterationPreparation = AgentLoopIterationPreparationService.Prepare(
+                    messages,
+                    _pendingCommands,
+                    lastToolResultAtUtc,
+                    lastToolResultToolName,
+                    DateTime.UtcNow);
+                if (!string.IsNullOrWhiteSpace(iterationPreparation.ToolResultWaitSummary))
                 {
-                    var waitMs = Math.Max(0, (long)(DateTime.UtcNow - toolResultAt).TotalMilliseconds);
                     WorkflowLogService.LogTransition(
                         _conversationId,
                         _currentRunId,
                         iteration,
                         "llm_wait_after_tool_result",
-                        $"{lastToolResultToolName ?? "unknown"}:{waitMs}ms");
+                        iterationPreparation.ToolResultWaitSummary);
                     lastToolResultAtUtc = null;
                     lastToolResultToolName = null;
                 }
 
-                // ── 실행 중 사용자 메시지 주입 (Claude Code 스타일 steering) ──
+                foreach (var evt in iterationPreparation.QueueProjection.Events)
-                DrainPendingCommands(messages);
+                    EmitEvent(evt.Type, evt.ToolName, evt.Summary);
 
-                var queryView = AgentQueryContextBuilder.Build(messages);
+                var queryView = iterationPreparation.QueryView;
                 var queryMessages = queryView.Messages;
                 if (queryView.BoundaryApplied || queryView.ToolPairExpanded || queryView.TruncatedToolResultCount > 0)
                 {

src/AxCopilot/Services/Agent/AgentMessageInvariantHelper.cs

@@ -11,11 +11,27 @@ internal static class AgentMessageInvariantHelper
     private const int SyntheticPreviewTextLimit = 280;
     private const int PreviewFingerprintTextLimit = 480;
 
+    internal sealed record ToolResultPreviewSnapshot(
+        IReadOnlyDictionary<string, string> ExplicitByToolResultId,
+        IReadOnlyDictionary<string, string> ExplicitByFingerprint,
+        IReadOnlyDictionary<string, string> SyntheticByToolResultId);
+
     public static Dictionary<string, string> BuildToolResultPreviewMap(IEnumerable<ChatMessage>? messages)
     {
-        var previews = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        var snapshot = BuildToolResultPreviewSnapshot(messages);
+        var merged = new Dictionary<string, string>(snapshot.SyntheticByToolResultId, StringComparer.OrdinalIgnoreCase);
+        foreach (var pair in snapshot.ExplicitByToolResultId)
+            merged[pair.Key] = pair.Value;
+        return merged;
+    }
+
+    internal static ToolResultPreviewSnapshot BuildToolResultPreviewSnapshot(IEnumerable<ChatMessage>? messages)
+    {
+        var explicitById = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        var explicitByFingerprint = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        var syntheticById = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
         if (messages == null)
-            return previews;
+            return new ToolResultPreviewSnapshot(explicitById, explicitByFingerprint, syntheticById);
 
         var bufferedMessages = messages as IList<ChatMessage> ?? messages.ToList();
 
@@ -26,20 +42,72 @@ internal static class AgentMessageInvariantHelper
             if (!TryGetToolResultId(message, out var toolResultId))
                 continue;
 
-            previews[toolResultId] = message.QueryPreviewContent!;
+            explicitById[toolResultId] = message.QueryPreviewContent!;
+            if (TryGetToolResultFingerprint(message, out var fingerprint))
+                explicitByFingerprint[fingerprint] = message.QueryPreviewContent!;
         }
 
         foreach (var message in bufferedMessages)
         {
-            if (!TryGetToolResultId(message, out var toolResultId) || previews.ContainsKey(toolResultId))
+            if (!TryGetToolResultId(message, out var toolResultId)
+                || explicitById.ContainsKey(toolResultId)
+                || syntheticById.ContainsKey(toolResultId))
                 continue;
+
+            if (TryGetToolResultFingerprint(message, out var fingerprint)
+                && explicitByFingerprint.ContainsKey(fingerprint))
+            {
+                // Another message already carries a stable persisted preview for this payload.
+                // Prefer rebound explicit previews over locally synthesized ones.
+                continue;
+            }
+
             if (!TryBuildSyntheticToolResultPreview(message, out var preview))
                 continue;
 
-            previews[toolResultId] = preview;
+            syntheticById[toolResultId] = preview;
         }
 
-        return previews;
+        return new ToolResultPreviewSnapshot(explicitById, explicitByFingerprint, syntheticById);
+    }
+
+    internal static bool TryResolveToolResultPreview(
+        ChatMessage message,
+        ToolResultPreviewSnapshot snapshot,
+        out string preview)
+    {
+        preview = "";
+        if (!TryGetToolResultId(message, out var toolResultId))
+            return false;
+
+        if (snapshot.ExplicitByToolResultId.TryGetValue(toolResultId, out var byIdPreview))
+        {
+            preview = byIdPreview;
+            return true;
+        }
+
+        if (TryGetToolResultFingerprint(message, out var fingerprint)
+            && snapshot.ExplicitByFingerprint.TryGetValue(fingerprint, out var fingerprintPreview))
+        {
+            preview = TryRebindToolResultPreview(fingerprintPreview, toolResultId, message, out var reboundPreview)
+                ? reboundPreview
+                : fingerprintPreview;
+            return true;
+        }
+
+        if (snapshot.SyntheticByToolResultId.TryGetValue(toolResultId, out var syntheticByIdPreview))
+        {
+            preview = syntheticByIdPreview;
+            return true;
+        }
+
+        if (TryBuildSyntheticToolResultPreview(message, out var syntheticPreview))
+        {
+            preview = syntheticPreview;
+            return true;
+        }
+
+        return false;
     }
 
     public static bool PopulateMissingToolResultPreviews(IList<ChatMessage>? messages)
@@ -47,9 +115,10 @@ internal static class AgentMessageInvariantHelper
         if (messages == null || messages.Count == 0)
             return false;
 
-        var previews = BuildPersistedToolResultPreviewMap(messages);
+        var snapshot = BuildToolResultPreviewSnapshot(messages);
-        var previewsByFingerprint = BuildToolResultPreviewFingerprintMap(messages);
+        if (snapshot.ExplicitByToolResultId.Count == 0
-        if (previews.Count == 0 && previewsByFingerprint.Count == 0)
+            && snapshot.ExplicitByFingerprint.Count == 0
+            && snapshot.SyntheticByToolResultId.Count == 0)
             return false;
 
         var changed = false;
@@ -57,22 +126,7 @@ internal static class AgentMessageInvariantHelper
         {
             if (!string.IsNullOrWhiteSpace(message.QueryPreviewContent))
                 continue;
-            if (!TryGetToolResultId(message, out var toolResultId))
+            if (!TryResolveToolResultPreview(message, snapshot, out var preview))
-                continue;
-
-            if (!previews.TryGetValue(toolResultId, out var preview))
-            {
-                if (!TryGetToolResultFingerprint(message, out var fingerprint)
-                    || !previewsByFingerprint.TryGetValue(fingerprint, out var fingerprintPreview))
-                {
-                    continue;
-                }
-
-                preview = TryRebindToolResultPreview(fingerprintPreview, toolResultId, message, out var reboundPreview)
-                    ? reboundPreview
-                    : fingerprintPreview;
-            }
-            else if (string.IsNullOrWhiteSpace(preview) && !TryBuildSyntheticToolResultPreview(message, out preview))
             {
                 continue;
             }
@@ -234,48 +288,6 @@ internal static class AgentMessageInvariantHelper
         }
     }
 
-    private static Dictionary<string, string> BuildToolResultPreviewFingerprintMap(IEnumerable<ChatMessage> messages)
-    {
-        var previews = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-
-        foreach (var message in messages)
-        {
-            if (!TryGetToolResultFingerprint(message, out var fingerprint))
-                continue;
-
-            if (!string.IsNullOrWhiteSpace(message.QueryPreviewContent))
-            {
-                previews[fingerprint] = message.QueryPreviewContent!;
-                continue;
-            }
-
-            if (previews.ContainsKey(fingerprint))
-                continue;
-
-            if (TryBuildSyntheticToolResultPreview(message, out var preview))
-                previews[fingerprint] = preview;
-        }
-
-        return previews;
-    }
-
-    private static Dictionary<string, string> BuildPersistedToolResultPreviewMap(IEnumerable<ChatMessage> messages)
-    {
-        var previews = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-
-        foreach (var message in messages)
-        {
-            if (string.IsNullOrWhiteSpace(message.QueryPreviewContent))
-                continue;
-            if (!TryGetToolResultId(message, out var toolResultId))
-                continue;
-
-            previews[toolResultId] = message.QueryPreviewContent!;
-        }
-
-        return previews;
-    }
-
     private static bool TryGetToolResultFingerprint(ChatMessage message, out string fingerprint)
     {
         fingerprint = "";

src/AxCopilot/Services/Agent/AgentToolResultBudget.cs

@@ -27,12 +27,20 @@ public static class AgentToolResultBudget
         IReadOnlyList<ChatMessage>? sourceMessages = null)
     {
         var result = new AgentToolResultBudgetResult();
-        AgentMessageInvariantHelper.PopulateMissingToolResultPreviews(messages);
+        var previewSourceMessages = sourceMessages ?? messages;
+        if (ReferenceEquals(previewSourceMessages, messages))
+        {
+            AgentMessageInvariantHelper.PopulateMissingToolResultPreviews(messages);
+        }
+        else if (previewSourceMessages is IList<ChatMessage> sourcePreviewList)
+        {
+            AgentMessageInvariantHelper.PopulateMissingToolResultPreviews(sourcePreviewList);
+        }
+
         var sourceById = sourceMessages?
             .Where(message => !string.IsNullOrWhiteSpace(message.MsgId))
             .ToDictionary(message => message.MsgId, StringComparer.OrdinalIgnoreCase);
-        var previewSourceMessages = sourceMessages ?? messages;
+        var previewSnapshot = AgentMessageInvariantHelper.BuildToolResultPreviewSnapshot(previewSourceMessages);
-        var sourcePreviewByToolResultId = AgentMessageInvariantHelper.BuildToolResultPreviewMap(previewSourceMessages);
         var nonSystemIndexes = messages
             .Select((message, index) => new { message, index })
             .Where(x => !string.Equals(x.message.Role, "system", StringComparison.OrdinalIgnoreCase))
@@ -59,8 +67,7 @@ public static class AgentToolResultBudget
             result.TotalCharsBefore += content.Length;
 
             if (string.IsNullOrWhiteSpace(message.QueryPreviewContent)
-                && AgentMessageInvariantHelper.TryGetToolResultId(message, out var toolResultId)
+                && AgentMessageInvariantHelper.TryResolveToolResultPreview(message, previewSnapshot, out var persistedPreview))
-                && sourcePreviewByToolResultId.TryGetValue(toolResultId, out var persistedPreview))
             {
                 message.QueryPreviewContent = persistedPreview;
                 if (sourceById != null