diff --git a/api/chat_session_service_test.go b/api/chat_session_service_test.go
index e3b4d408..76e22b6e 100644
--- a/api/chat_session_service_test.go
+++ b/api/chat_session_service_test.go
@@ -46,7 +46,7 @@ func TestChatSessionService(t *testing.T) {
 	}
 
 	// Check that updated chat session matches expected values
-	// TODO: timezone time || !retrievedSession.UpdatedAt.Equal(updated_params.UpdatedAt)
+	// UpdatedAt is generated by the database; verify updated fields instead of strict timestamp equality.
 	if retrievedSession.Topic != updated_params.Topic {
 		t.Errorf("chat session mismatch: expected Topic=%s,  got Topic=%s ",
 			updated_params.Topic, retrievedSession.Topic)
diff --git a/api/model_gemini_service.go b/api/model_gemini_service.go
index f7abcb5d..77acb371 100644
--- a/api/model_gemini_service.go
+++ b/api/model_gemini_service.go
@@ -83,11 +83,13 @@ func (m *GeminiChatModel) Stream(w http.ResponseWriter, chatSession sqlc_queries
 
 	llmAnswer, err := gemini.HandleRegularResponse(*m.client.client, req)
 	if err != nil {
-		return nil, ErrInternalUnexpected.WithMessage("Failed to generate regular resposne").WithDebugInfo(err.Error())
+		return nil, ErrInternalUnexpected.WithMessage("Failed to generate regular response").WithDebugInfo(err.Error())
 	}
-	if llmAnswer != nil {
-		llmAnswer.AnswerId = answerID
+	if llmAnswer == nil {
+		return nil, ErrInternalUnexpected.WithMessage("Empty response from Gemini")
 	}
+
+	llmAnswer.AnswerId = answerID
 	response := constructChatCompletionStreamResponse(answerID, llmAnswer.Answer)
 	data, _ := json.Marshal(response)
 	fmt.Fprint(w, string(data))
diff --git a/api/util_test.go b/api/util_test.go
index d17a915d..51cc0012 100644
--- a/api/util_test.go
+++ b/api/util_test.go
@@ -14,7 +14,11 @@ func Test_firstN(t *testing.T) {
 	}{
 		{"01", args{"hello", 2}, "he"},
 		{"02", args{"hello", 5}, "hello"},
-		{"02", args{"hello", 50}, "hello"},
+		{"03", args{"hello", 50}, "hello"},
+		{"04", args{"你好世界", 2}, "你好"},
+		{"05", args{"", 3}, ""},
+		{"06", args{"hello", 0}, ""},
+		{"07", args{"🙂🙃", 1}, "🙂"},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
diff --git a/docs/artifact_gallery_en.md b/docs/artifact_gallery_en.md
index 625ce0ed..75a3b394 100644
--- a/docs/artifact_gallery_en.md
+++ b/docs/artifact_gallery_en.md
@@ -233,20 +233,12 @@ The gallery integrates with the chat application's API:
 
 ```javascript
 // Example: Getting artifacts from a specific session
-const artifacts = await fetch(`/api/chat/sessions/${sessionId}/artifacts`);
+const messages = await fetch(`/api/uuid/chat_messages/chat_sessions/${sessionId}`);
+// Artifacts are included in each message payload as the `artifacts` field
 
 // Example: Executing code artifact
-const result = await fetch(`/api/artifacts/${artifactId}/execute`, {
-  method: 'POST',
-  headers: {
-    'Content-Type': 'application/json',
-    'Authorization': `Bearer ${token}`
-  },
-  body: JSON.stringify({
-    code: artifactContent,
-    language: 'javascript'
-  })
-});
+// Code execution is handled client-side in Artifact Editor/Sandbox components,
+// not by a dedicated backend `/api/artifacts/:id/execute` endpoint.
 ```
 
 ## Future Enhancements
diff --git a/docs/artifact_gallery_zh.md b/docs/artifact_gallery_zh.md
index 1f3a2bea..4cf77c95 100644
--- a/docs/artifact_gallery_zh.md
+++ b/docs/artifact_gallery_zh.md
@@ -233,20 +233,12 @@
 
 ```javascript
 // 示例：从特定会话获取制品
-const artifacts = await fetch(`/api/chat/sessions/${sessionId}/artifacts`);
+const messages = await fetch(`/api/uuid/chat_messages/chat_sessions/${sessionId}`);
+// 制品包含在每条消息的 `artifacts` 字段中
 
 // 示例：执行代码制品
-const result = await fetch(`/api/artifacts/${artifactId}/execute`, {
-  method: 'POST',
-  headers: {
-    'Content-Type': 'application/json',
-    'Authorization': `Bearer ${token}`
-  },
-  body: JSON.stringify({
-    code: artifactContent,
-    language: 'javascript'
-  })
-});
+// 代码执行由前端的 Artifact Editor/Sandbox 组件处理，
+// 后端没有独立的 `/api/artifacts/:id/execute` 接口。
 ```
 
 ## 未来增强