# 計費常見問題

<details>

<summary>失敗的請求會扣 credit 嗎？</summary>

不會。credit **只在成功（2xx）回應時**扣除。任何 4xx／5xx 錯誤都不扣點。

</details>

<details>

<summary>我怎麼即時知道餘額？</summary>

每個成功回應的 `X-Credit-Remaining` header（以及 `meta.credit_remaining`）都會帶當前餘額。建議在你的系統中記錄此值，於低水位時提前告警。

</details>

<details>

<summary>每次呼叫扣多少點？</summary>

依端點而定，每個端點有各自的成本權重。實際扣除量會出現在回應的 `X-Credit-Cost`。管理與系統端點為 0。

</details>

<details>

<summary>餘額用完了會怎樣？</summary>

請求會回 `402 insufficient_credit` 並停止計費。請聯絡管理員加值後即可恢復。

</details>

<details>

<summary>不同 API key 的 credit 會共用嗎？</summary>

不會。每把 key 有獨立的餘額，互不影響。這也方便你針對不同整合分別控管用量。

</details>

<details>

<summary>我可以查歷史用量嗎？</summary>

系統會將每筆扣點寫入帳本並關聯 `request_id`。如需用量明細報表，請聯絡你的客戶經理。

</details>


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