Fix empty tool-use response handling

s03_permission/README.zh.md

@@ -108,13 +108,12 @@ def check_permission(block) -> bool:
     return True
 
 # 在 agent_loop 中——s02 的循环只加了一行：
-for block in response.content:
-    if block.type == "tool_use":
-        if not check_permission(block):           # ← 新增
-            results.append({... "content": "Permission denied."})
-            continue
-        output = TOOL_HANDLERS[block.name](**block.input)  # s02 原有
-        results.append(...)
+for block in tool_calls:
+    if not check_permission(block):           # ← 新增
+        results.append({... "content": "Permission denied."})
+        continue
+    output = TOOL_HANDLERS[block.name](**block.input)  # s02 原有
+    results.append(...)
 ```
 
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