go get github.com/anthropics/anthropic-sdk-go

tools := []anthropic.ToolUnionParam{
	{OfTool: &anthropic.ToolParam{
		Name:        "disk_usage",
		Description: anthropic.String("列出所有掛載點的磁碟使用狀況（df -h）"),
		InputSchema: anthropic.ToolInputSchemaParam{Properties: map[string]any{}},
	}},
	{OfTool: &anthropic.ToolParam{
		Name:        "largest_entries",
		Description: anthropic.String("列出指定目錄下佔用空間最大的子目錄，依大小遞減排序。用於逐層追查磁碟空間被誰吃掉。"),
		InputSchema: anthropic.ToolInputSchemaParam{
			Properties: map[string]any{
				"path": map[string]any{"type": "string", "description": "要分析的目錄絕對路徑"},
				"top":  map[string]any{"type": "integer", "description": "回傳前幾名，預設 10"},
			},
			Required: []string{"path"},
		},
	}},
}

func execute(name string, input json.RawMessage) (string, bool) {
	switch name {
	case "disk_usage":
		out, err := runCmd("df -h")
		if err != nil {
			return out + err.Error(), true // 第二個回傳值：是不是錯誤
		}
		return out, false

	case "largest_entries":
		var in struct {
			Path string `json:"path"`
			Top  int    `json:"top"`
		}
		if err := json.Unmarshal(input, &in); err != nil {
			return "參數解析失敗: " + err.Error(), true
		}
		if in.Top == 0 {
			in.Top = 10 // 選填參數自己補預設值
		}
		out, err := runCmd(fmt.Sprintf(
			"du -h -d 1 %q 2>/dev/null | sort -rh | head -n %d", in.Path, in.Top))
		if err != nil && out == "" {
			return err.Error(), true
		}
		return out, false
	}
	return "未知的工具: " + name, true
}

messages := []anthropic.MessageParam{
	anthropic.NewUserMessage(anthropic.NewTextBlock(
		"/var 的空間快滿了，幫我找出是誰吃掉的，最後給我前三大兇手和建議")),
}

ctx := context.Background()
for i := 0; i < 10; i++ { // 迴圈上限，避免燒錢的保險絲
	resp, err := client.Messages.New(ctx, anthropic.MessageNewParams{
		Model:     anthropic.ModelClaudeOpus4_8,
		MaxTokens: 16000,
		Messages:  messages,
		Tools:     tools,
	})
	if err != nil {
		log.Fatal(err)
	}

	// 關鍵一：先把 assistant 的回應「原封不動」放回對話歷史
	messages = append(messages, resp.ToParam())

	toolResults := []anthropic.ContentBlockParamUnion{}
	for _, block := range resp.Content {
		switch v := block.AsAny().(type) {
		case anthropic.TextBlock:
			fmt.Println(v.Text)
		case anthropic.ToolUseBlock:
			fmt.Printf("→ %s(%s)\n", v.Name, v.JSON.Input.Raw())
			result, isErr := execute(v.Name, json.RawMessage(v.JSON.Input.Raw()))
			toolResults = append(toolResults, anthropic.NewToolResultBlock(v.ID, result, isErr))
		}
	}

	if resp.StopReason != anthropic.StopReasonToolUse {
		return // end_turn：模型說回答完了
	}

	// 關鍵二：所有 tool_result 放在「同一則」user message 裡送回去
	messages = append(messages, anthropic.NewUserMessage(toolResults...))
}
log.Fatal("超過迴圈上限，中止")