Payment infrastructure for

const flux = new FluxHostedFields(  authToken, publicKey); // from your serverflux.elements().create('cardNumber')  .mount('#card-number');// + the other 11 fields, email and phone toopayButton.onclick = async () => {  const r = await flux.createToken();  if (r.error) return show(r.error.message);  charge(r.cardToken); // server prices it};mounted readyHosted fields

app.post('/webhooks/flux', (req, res) => {  const sig = req.get('Flux-Signature');  if (!verifyFlux(req.rawBody, sig, SECRET))    return res.sendStatus(400);  const e = JSON.parse(req.rawBody);  if (e.type === 'charge.succeeded')    queue(e); // de-dupe on e.id  res.sendStatus(200);});

POST /v2/payment-linksX-Idempotency-Key: 9f1a6c42-...{  "accountEmail": "pat@example.com",  "firstName": "Pat", "lastName": "Lee",  "products": [{ "id": 5521, "quantity": 1 }]}// 5521 = Pro Plan, type "SUBSCRIPTION",// subscriptionInterval "MONTHLY"200 OK paymentLinkUrlPay link

app.post('/webhooks/flux', (req, res) => {  const sig = req.get('Flux-Signature');  if (!verifyFlux(req.rawBody, sig, SECRET))    return res.sendStatus(400);  const e = JSON.parse(req.rawBody);  if (e.type === 'subscription.created')    grant(e.data.subscriptionId);  if (e.type === 'subscription.cancelled')    revoke(e.data.subscriptionId);  res.sendStatus(200);});

POST /v2/webhook-endpointsX-Idempotency-Key: 1e4b77d0-...{  "url": "https://api.example.com/flux",  "events": ["charge.succeeded",    "subscription.created",    "subscription.cancelled"]}200 OK secret: whsec_...Signing secret

import hmac, hashlib, timedef verify(raw, h, key):  # bytes, str, bytes  kv = [p.split('=', 1) for p in h.split(',')]  t = dict(kv)['t']  if abs(time.time() - int(t)) > 300:    return False  mac = hmac.new(key, t.encode() + b'.' + raw,    hashlib.sha256).hexdigest()  return any(hmac.compare_digest(mac, v)    for k, v in kv if k == 'v1')