結果のコールバック

curl https://www.aisplice.store/v1/videos \
  -H "Authorization: Bearer sk-YOUR_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: video-job-8842" \
  -d '{
    "model": "doubao-seedance-2.5",
    "prompt": "A cinematic product scene",
    "webhook_url": "https://your.app/hooks/ai-tasks",
    "webhook_secret": "whsec_replace_me"
  }'

{
  "event_id": "task_8f21c...:task.completed",
  "event": "task.completed",
  "task_id": "8f21c0d2-...",
  "status": "completed",
  "model": "doubao-seedance-2.5",
  "url": "https://cdn.example.com/renders/8f21c0d2.mp4",
  "quota": 128000,
  "created_at": 1789000000,
  "finished_at": 1789000184
}

import crypto from "node:crypto";

// Express: express.raw({ type: "application/json" }) — not express.json().
export function handleTaskWebhook(req, res) {
  const received = req.get("X-Xiaoxiang-Signature") ?? "";
  const expected =
    "sha256=" +
    crypto.createHmac("sha256", process.env.WEBHOOK_SECRET)
      .update(req.body)              // Buffer of the raw body
      .digest("hex");

  const a = Buffer.from(received);
  const b = Buffer.from(expected);
  if (a.length !== b.length || !crypto.timingSafeEqual(a, b)) {
    return res.status(401).end();
  }

  const event = JSON.parse(req.body.toString("utf8"));
  // Deduplicate first, acknowledge fast, then do the work off-request.
  if (!seen.add(req.get("X-Xiaoxiang-Event-Id"))) return res.status(200).end();
  queue.push(event);
  res.status(200).end();
}