탭 전환 빈 대화 누적 방지: 저장 게이트 + 목록 노이즈 필터

- ChatSessionStateService.SaveCurrentConversation에 persistable-content 검사 추가

- 무의미한 빈 새 대화는 저장/탭 기억 대상에서 제외

- ChatWindow 대화 목록에서 빈 노이즈 항목 필터링

- ChatSessionStateServiceTests 회귀 추가 및 문서 이력(2026-04-04 15:48 KST) 동기화

src/AxCopilot.Tests/Services/ChatSessionStateServiceTests.cs

@@ -225,6 +225,32 @@ public class ChatSessionStateServiceTests
         session.GetConversationId("Code").Should().Be(conv.Id);
     }
 
+    [Fact]
+    public void SaveCurrentConversation_DoesNotPersistEmptyFreshConversation()
+    {
+        var session = new ChatSessionStateService();
+        var storage = new ChatStorageService();
+        var conv = session.EnsureCurrentConversation("Cowork");
+        conv.Messages.Clear();
+        conv.ExecutionEvents.Clear();
+        conv.AgentRunHistory.Clear();
+        conv.DraftQueueItems.Clear();
+        conv.Preview = "";
+        conv.WorkFolder = "";
+        conv.SystemCommand = "";
+        conv.Permission = null;
+        conv.DataUsage = null;
+        conv.OutputFormat = null;
+        conv.Mood = null;
+        conv.Category = ChatCategory.General;
+        conv.Title = "새 대화";
+
+        session.SaveCurrentConversation(storage, "Cowork");
+
+        session.GetConversationId("Cowork").Should().BeNull();
+        storage.Load(conv.Id).Should().BeNull();
+    }
+
     [Fact]
     public void SaveCurrentConversation_RemembersConversationId_WhenOnlyAgentRunHistoryExists()
     {
@@ -701,4 +727,54 @@ public class ChatSessionStateServiceTests
         session.GetConversationId("Code").Should().BeNull();
         session.GetConversationId("Chat").Should().BeNull();
     }
+
+    [Fact]
+    public void LoadOrCreateConversation_RestoresRunHistoryAndExecutionEventsAfterRestart()
+    {
+        var storage = new ChatStorageService();
+        var settings = new SettingsService();
+        var sessionA = new ChatSessionStateService();
+        var conv = new ChatConversation
+        {
+            Id = $"conv-replay-{Guid.NewGuid():N}",
+            Tab = "Code",
+            Title = "restore test",
+            Messages = [new ChatMessage { Role = "user", Content = "build it" }],
+            ExecutionEvents =
+            [
+                new ChatExecutionEvent
+                {
+                    RunId = "run-restore-1",
+                    Type = "ToolResult",
+                    ToolName = "build_run",
+                    Summary = "build ok",
+                    Timestamp = DateTime.Now
+                }
+            ],
+            AgentRunHistory =
+            [
+                new ChatAgentRunRecord
+                {
+                    RunId = "run-restore-1",
+                    Status = "completed",
+                    Summary = "done",
+                    UpdatedAt = DateTime.Now
+                }
+            ]
+        };
+
+        sessionA.SetCurrentConversation("Code", conv, storage);
+        sessionA.SaveCurrentConversation(storage, "Code");
+        sessionA.Save(settings);
+
+        var sessionB = new ChatSessionStateService();
+        sessionB.Load(settings);
+        var restored = sessionB.LoadOrCreateConversation("Code", storage, settings);
+
+        restored.Id.Should().Be(conv.Id);
+        restored.Tab.Should().Be("Code");
+        restored.ExecutionEvents.Should().ContainSingle();
+        restored.AgentRunHistory.Should().ContainSingle();
+        restored.AgentRunHistory[0].RunId.Should().Be("run-restore-1");
+    }
 }