diff --git a/agent/checkpoint_utils.py b/agent/checkpoint_utils.py
index a346070..d4ee1da 100644
--- a/agent/checkpoint_utils.py
+++ b/agent/checkpoint_utils.py
@@ -30,41 +30,13 @@ async def check_checkpoint_history(checkpointer: MemorySaver, thread_id: str) ->
         logger.debug(f"Checkpointer type: {type(checkpointer)}")
         logger.debug(f"Checkpointer dir: {[attr for attr in dir(checkpointer) if not attr.startswith('_')]}")
 
-        # 先尝试获取最新的 checkpoint
-        try:
-            latest_checkpoint = await checkpointer.aget_tuple(config)
-            logger.debug(f"aget_tuple result: {latest_checkpoint}")
-
-            if latest_checkpoint is not None:
-                logger.info(f"Found latest checkpoint for thread_id: {thread_id}")
-                # 解构 checkpoint tuple
-                checkpoint_config, checkpoint, metadata = latest_checkpoint
-                logger.debug(f"Checkpoint metadata: {metadata}")
-                return True
-        except Exception as e:
-            logger.warning(f"aget_tuple failed: {e}")
-
-        # 如果没有最新的，再列出所有
-        logger.debug(f"No latest checkpoint for thread_id: {thread_id}, checking all checkpoints...")
-        try:
-            checkpoints = []
-            async for c in checkpointer.alist(config):
-                checkpoints.append(c)
-                logger.debug(f"Found checkpoint: {c}")
-
-            # 如果有至少一个 checkpoint，说明有历史记录
-            has_history = len(checkpoints) > 0
-
-            if has_history:
-                logger.info(f"Found {len(checkpoints)} checkpoints in total for thread_id: {thread_id}")
-            else:
-                logger.info(f"No existing history for thread_id: {thread_id}")
-
-            return has_history
-        except Exception as e:
-            logger.warning(f"alist failed: {e}")
-            return False
+        latest_checkpoint = await checkpointer.aget_tuple(config)
+        logger.debug(f"aget_tuple result: {latest_checkpoint}")
 
+        if latest_checkpoint is not None:
+            logger.info(f"Found latest checkpoint for thread_id: {thread_id}")
+            # 解构 checkpoint tuple
+            return True
     except Exception as e:
         import traceback
         logger.error(f"Error checking checkpoint history for thread_id {thread_id}: {e}")
diff --git a/agent/deep_assistant.py b/agent/deep_assistant.py
index 4373888..2a70cc3 100644
--- a/agent/deep_assistant.py
+++ b/agent/deep_assistant.py
@@ -11,6 +11,9 @@ from langchain_mcp_adapters.client import MultiServerMCPClient
 from langgraph.checkpoint.memory import MemorySaver
 from utils.fastapi_utils import detect_provider
 
+# 全局 MemorySaver 实例
+_global_checkpointer = MemorySaver()
+
 from .guideline_middleware import GuidelineMiddleware
 from .tool_output_length_middleware import ToolOutputLengthMiddleware
 from utils.settings import SUMMARIZATION_MAX_TOKENS, TOOL_OUTPUT_MAX_LENGTH
@@ -117,7 +120,7 @@ async def init_agent(config: AgentConfig):
     checkpointer = None
 
     if config.session_id:
-        checkpointer = MemorySaver()
+        checkpointer = _global_checkpointer
         summarization_middleware = SummarizationMiddleware(
             model=llm_instance,
             max_tokens_before_summary=SUMMARIZATION_MAX_TOKENS,