diff --git a/s05_todo_write/code.py b/s05_todo_write/code.py
index 9c88de35..33fda525 100644
--- a/s05_todo_write/code.py
+++ b/s05_todo_write/code.py
@@ -236,6 +236,7 @@ rounds_since_todo = 0
 
 def agent_loop(messages: list):
     global rounds_since_todo
+    rounds_since_todo = 0  # 每轮新对话从0开始计数
     while True:
         # s05: nag reminder — inject if model hasn't updated todos for 3 rounds
         if rounds_since_todo >= 3 and messages:
diff --git a/s06_subagent/code.py b/s06_subagent/code.py
index 2732246b..f4299171 100644
--- a/s06_subagent/code.py
+++ b/s06_subagent/code.py
@@ -316,6 +316,7 @@ rounds_since_todo = 0
 
 def agent_loop(messages: list):
     global rounds_since_todo
+    rounds_since_todo = 0  # 每轮新对话从0开始计数
     while True:
         # s05: nag reminder
         if rounds_since_todo >= 3 and messages:
diff --git a/s07_skill_loading/code.py b/s07_skill_loading/code.py
index b4506fc5..20c3b196 100644
--- a/s07_skill_loading/code.py
+++ b/s07_skill_loading/code.py
@@ -360,6 +360,7 @@ rounds_since_todo = 0
 
 def agent_loop(messages: list):
     global rounds_since_todo
+    rounds_since_todo = 0  # 每轮新对话从0开始计数
     while True:
         if rounds_since_todo >= 3 and messages:
             messages.append({"role": "user",