RFC 7231: Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content
https://www.rfc-editor.org/rfc/rfc7231.html#section-6.3.3
> 6.3.3. 202 Accepted
>
> The 202 (Accepted) status code indicates that the request has been accepted for processing, but the processing has not been completed.
いや普通にこれでいいじゃん
「ステータスコード 202 (Accepted) は、要求が処理対象として受理されたものの処理自体は完了していないことを示す。」
> The representation sent with this response ought to describe the request's current status and point to (or embed) a status monitor that can provide the user with an estimate of when the request will be fulfilled.
状況がわかるような手段を一緒に提供しろと。まあそりゃそうだわな