Fix frontend opener showing

engine/core/duplex_pipeline.py

@@ -409,12 +409,13 @@ class DuplexPipeline:
 
         prompt_hint = (self._runtime_greeting or "").strip()
         system_prompt = (
-            "You generate one concise opener for a live voice call assistant. "
-            "Return plain text only, no quotes, no markdown, one sentence."
+            "你是语音通话助手的开场白生成器。"
+            "请只输出一句自然、简洁、友好的中文开场白。"
+            "不要使用引号，不要使用 markdown，不要加解释。"
         )
-        user_prompt = "Generate a friendly opening line (max 25 words)."
+        user_prompt = "请生成一句中文开场白（不超过25个汉字）。"
         if prompt_hint:
-            user_prompt += f" Style hint: {prompt_hint}"
+            user_prompt += f" 风格提示：{prompt_hint}"
 
         try:
             generated = await self.llm_service.generate(