diff --git a/src/ETTerms/Ai/AgentHost.cs b/src/ETTerms/Ai/AgentHost.cs
index 8ba5112..5621242 100644
--- a/src/ETTerms/Ai/AgentHost.cs
+++ b/src/ETTerms/Ai/AgentHost.cs
@@ -14,7 +14,9 @@ public sealed class AgentHost
     private readonly OpenAiChatClient _client;
     private readonly AiTools _tools;
     private readonly JsonArray _messages = new();
-    private const int MaxToolRounds = 8;
+    // 單次 SendAsync 的工具呼叫輪數上限（防失控迴圈的保險）。硬體任務常需多輪
+    // （逐一操作多個 port、多次讀寫、power-cycle 等待…）,故放寬到 30。
+    private const int MaxToolRounds = 30;
 
     public event Action<string>? AssistantText;   // 最終文字回應
     public event Action<string>? ToolActivity;     // 「呼叫 serial_write …」之類過程