better：优化prompt，修改buffer行为（更严格判定降低延迟，不丢弃图片前文本）

src/plugins/utils/chat_message_builder.py

@@ -168,7 +168,10 @@ async def _build_readable_messages_internal(
         user_info = msg.get("user_info", {})
         platform = user_info.get("platform")
         user_id = user_info.get("user_id")
-        user_nickname = user_info.get("nickname")
+        
+        user_nickname = user_info.get("user_nickname")
+        user_cardname = user_info.get("user_cardname")
+        
         timestamp = msg.get("time")
         content = msg.get("processed_plain_text", "")  # 默认空字符串
 
@@ -186,7 +189,12 @@ async def _build_readable_messages_internal(
 
         # 如果 person_name 未设置，则使用消息中的 nickname 或默认名称
         if not person_name:
-            person_name = user_nickname
+            if user_cardname:
+                person_name = f"昵称：{user_cardname}"
+            elif user_nickname:
+                person_name = f"{user_nickname}"
+            else:
+                person_name = "某人"
 
         message_details.append((timestamp, person_name, content))
 
@@ -304,7 +312,7 @@ async def build_readable_messages(
 
         readable_read_mark = translate_timestamp_to_human_readable(read_mark, mode=timestamp_mode)
         read_mark_line = (
-            f"\n\n--- 以上消息已读 (标记时间: {readable_read_mark}) ---\n--- 以下新消息未读---\n"
+            f"\n--- 以上消息已读 (标记时间: {readable_read_mark}) ---\n--- 以下新消息未读---\n"
         )
 
         # 组合结果，确保空部分不引入多余的标记或换行