diff --git a/core/web_terminal.py b/core/web_terminal.py
index 8669abcf..9d82ad3d 100644
--- a/core/web_terminal.py
+++ b/core/web_terminal.py
@@ -835,10 +835,14 @@ class WebTerminal(MainTerminal):
     def __del__(self):
         """析构函数，确保资源释放"""
         try:
-            # 保存当前对话
+            # 保存当前对话（仅当内存中确有消息时）。
+            # 竞态重建/回收场景下，被丢弃的实例可能只设了
+            # current_conversation_id 而 conversation_history 为空，
+            # 此时保存会把磁盘上非空的对话覆盖成空消息。
             if hasattr(self, 'context_manager') and self.context_manager:
-                if self.context_manager.current_conversation_id:
-                    self.context_manager.save_current_conversation()
+                cm = self.context_manager
+                if cm.current_conversation_id and getattr(cm, 'conversation_history', None):
+                    cm.save_current_conversation()
             
             # 关闭所有终端
             if hasattr(self, 'terminal_manager') and self.terminal_manager:
diff --git a/server/context.py b/server/context.py
index 4ffdb75f..44455b0d 100644
--- a/server/context.py
+++ b/server/context.py
@@ -893,7 +893,8 @@ def reap_idle_conversation_terminals(now: Optional[float] = None) -> int:
             continue
         try:
             cm = getattr(terminal, "context_manager", None)
-            if cm and getattr(cm, "current_conversation_id", None):
+            # 与 __del__ 同理：空 history 保存会把磁盘上非空对话覆盖为空
+            if cm and getattr(cm, "current_conversation_id", None) and getattr(cm, "conversation_history", None):
                 cm.save_current_conversation()
         except Exception as exc:
             debug_log(f"[ConvTerminalReaper] 保存对话失败 {conversation_id}: {exc}")