diff --git a/src/state.py b/src/state.py
index b39d97f..e69d605 100644
--- a/src/state.py
+++ b/src/state.py
@@ -1,11 +1,15 @@
 # src/state.py
 import os
 import json
+import time
+from datetime import datetime
+
 
 class StateTracker:
     def __init__(self, workspace_dir):
         self.state_file = os.path.join(workspace_dir, "workflow_status.json")
-        self.completed_tasks = set()
+        self.history = []  # 用于存储有序的记录 [{'task': id, 'time': time}, ...]
+        self.completed_set = set()  # 用于快速查找
         self.load()
 
     def load(self):
@@ -13,19 +17,45 @@ class StateTracker:
             try:
                 with open(self.state_file, 'r') as f:
                     data = json.load(f)
-                    self.completed_tasks = set(data.get("completed", []))
-            except:
-                self.completed_tasks = set()
+                    # 兼容旧版本：如果 data["completed"] 是纯字符串列表
+                    raw_list = data.get("completed", [])
+                    if raw_list and isinstance(raw_list[0], str):
+                        # 旧版本转换：给个假时间
+                        self.history = [{"task": task, "time": "Unknown"} for task in raw_list]
+                    else:
+                        # 新版本直接读取
+                        self.history = raw_list
+
+                    # 重建集合用于快速判断 is_done
+                    self.completed_set = {item['task'] for item in self.history}
+            except Exception as e:
+                print(f"Warning: Failed to load state file: {e}")
+                self.history = []
+                self.completed_set = set()
 
     def mark_done(self, task_id):
-        """标记任务完成并保存"""
-        self.completed_tasks.add(task_id)
+        """标记任务完成并保存（带时间戳）"""
+        if task_id in self.completed_set:
+            return  # 避免重复记录
+
+        # 获取当前时间
+        timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+
+        # 添加记录
+        record = {
+            "task": task_id,
+            "time": timestamp
+        }
+        self.history.append(record)
+        self.completed_set.add(task_id)
+
         self.save()
 
     def is_done(self, task_id):
         """检查任务是否已完成"""
-        return task_id in self.completed_tasks
+        return task_id in self.completed_set
 
     def save(self):
         with open(self.state_file, 'w') as f:
-            json.dump({"completed": list(self.completed_tasks)}, f, indent=2)
\ No newline at end of file
+            # indent=2 让文件更易读
+            json.dump({"completed": self.history}, f, indent=2, ensure_ascii=False)
\ No newline at end of file