リクエストが消えたあとで、ジョブを終わらせる。

import { createHash, createHmac, timingSafeEqual } from "node:crypto";

// rawBody is the exact bytes that arrived. Parse only to read the task ID:
// the digest is always computed over those raw bytes, never over a re-encode.
export function verifyDelivery(rawBody, headers, webhookKey) {
  const timestamp = headers["x-webhook-timestamp"];
  if (Math.abs(Date.now() / 1000 - Number(timestamp)) > 300) return false;

  const taskId = JSON.parse(rawBody).data.taskId;          // payload version 2
  const digest = createHash("sha256").update(rawBody).digest("hex");
  const expected = createHmac("sha256", webhookKey)
    .update(`${taskId}.${timestamp}.${digest}`)
    .digest("base64");

  const sent = Buffer.from(headers["x-webhook-signature"] ?? "", "utf8");
  const mine = Buffer.from(expected, "utf8");
  return sent.length === mine.length && timingSafeEqual(sent, mine);
}