AX Agent 채팅 UI 백업 및 claw-code 기준 엔진 재정렬

- ChatWindow 현재 UI와 엔진 기준본을 etc/chat-ui-backup/2026-04-05-1215에 백업해 회귀 비교 지점을 확보함

- 메시지 컬럼과 컴포저 폭을 claw-code식 단일 축으로 다시 맞추고 입력 셸을 안정적인 하단 컬럼 구조로 정리함

- 입력창 높이를 실제 줄바꿈 수 기준으로 다시 계산해 전송 후 높이가 남는 버그를 줄임

- 메시지 편집/피드백 후 재생성 경로의 직접 UI 버블 주입을 제거하고 RenderMessages 중심으로 통합함

- SendRegenerateAsync가 Cowork/Code에서 ResolveExecutionMode와 RunAgentLoopAsync를 타도록 바꿔 재생성도 동일 엔진 축으로 정렬함

- 검증: dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\\ 경고 0 / 오류 0

etc/chat-ui-backup/2026-04-05-1215/AxAgentExecutionEngine.cs

@@ -0,0 +1,128 @@
+using AxCopilot.Models;
+using AxCopilot.Services;
+
+namespace AxCopilot.Services.Agent;
+
+/// <summary>
+/// AX Agent execution-prep engine.
+/// Inspired by the `claw-code` split between input preparation and session execution,
+/// so the UI layer stops owning message assembly and final assistant commit logic.
+/// </summary>
+public sealed class AxAgentExecutionEngine
+{
+    public sealed record PreparedTurn(List<ChatMessage> Messages);
+    public sealed record ExecutionMode(bool UseAgentLoop, bool UseStreamingTransport, string? TaskSystemPrompt);
+
+    public IReadOnlyList<string> BuildPromptStack(
+        string? conversationSystem,
+        string? slashSystem,
+        string? taskSystem = null)
+    {
+        var prompts = new List<string>();
+        if (!string.IsNullOrWhiteSpace(conversationSystem))
+            prompts.Add(conversationSystem.Trim());
+        if (!string.IsNullOrWhiteSpace(slashSystem))
+            prompts.Add(slashSystem.Trim());
+        if (!string.IsNullOrWhiteSpace(taskSystem))
+            prompts.Add(taskSystem.Trim());
+        return prompts;
+    }
+
+    public ExecutionMode ResolveExecutionMode(
+        string runTab,
+        bool streamingEnabled,
+        string resolvedService,
+        string? coworkSystemPrompt,
+        string? codeSystemPrompt)
+    {
+        if (string.Equals(runTab, "Cowork", StringComparison.OrdinalIgnoreCase))
+            return new ExecutionMode(true, false, coworkSystemPrompt);
+
+        if (string.Equals(runTab, "Code", StringComparison.OrdinalIgnoreCase))
+            return new ExecutionMode(true, false, codeSystemPrompt);
+
+        return new ExecutionMode(false, false, null);
+    }
+
+    public PreparedTurn PrepareTurn(
+        ChatConversation conversation,
+        IEnumerable<string?> systemPrompts,
+        string? fileContext = null,
+        IReadOnlyList<ImageAttachment>? images = null)
+    {
+        var outbound = conversation.Messages
+            .Select(CloneMessage)
+            .ToList();
+
+        if (!string.IsNullOrWhiteSpace(fileContext))
+        {
+            var lastUserIndex = outbound.FindLastIndex(m => string.Equals(m.Role, "user", StringComparison.OrdinalIgnoreCase));
+            if (lastUserIndex >= 0)
+                outbound[lastUserIndex].Content = (outbound[lastUserIndex].Content ?? string.Empty) + fileContext;
+        }
+
+        if (images is { Count: > 0 })
+        {
+            var lastUserIndex = outbound.FindLastIndex(m => string.Equals(m.Role, "user", StringComparison.OrdinalIgnoreCase));
+            if (lastUserIndex >= 0)
+                outbound[lastUserIndex].Images = images.Select(CloneImage).ToList();
+        }
+
+        var promptList = systemPrompts
+            .Where(prompt => !string.IsNullOrWhiteSpace(prompt))
+            .Select(prompt => prompt!.Trim())
+            .ToList();
+
+        for (var i = promptList.Count - 1; i >= 0; i--)
+            outbound.Insert(0, new ChatMessage { Role = "system", Content = promptList[i] });
+
+        return new PreparedTurn(outbound);
+    }
+
+    public ChatMessage CommitAssistantMessage(
+        ChatSessionStateService? session,
+        ChatConversation conversation,
+        string tab,
+        string content,
+        ChatStorageService? storage = null)
+    {
+        var assistant = new ChatMessage
+        {
+            Role = "assistant",
+            Content = content,
+        };
+
+        if (session != null)
+        {
+            session.AppendMessage(tab, assistant, storage);
+            return assistant;
+        }
+
+        conversation.Messages.Add(assistant);
+        conversation.UpdatedAt = DateTime.Now;
+        return assistant;
+    }
+
+    private static ChatMessage CloneMessage(ChatMessage source)
+    {
+        return new ChatMessage
+        {
+            Role = source.Role,
+            Content = source.Content,
+            Timestamp = source.Timestamp,
+            MetaRunId = source.MetaRunId,
+            AttachedFiles = source.AttachedFiles?.ToList(),
+            Images = source.Images?.Select(CloneImage).ToList(),
+        };
+    }
+
+    private static ImageAttachment CloneImage(ImageAttachment source)
+    {
+        return new ImageAttachment
+        {
+            Base64 = source.Base64,
+            MimeType = source.MimeType,
+            FileName = source.FileName,
+        };
+    }
+}