Your software sells.
AgentKuber keeps the books.

import hashlib, hmac, json, os, time, urllib.request

def send(event: dict) -> dict:
    body = json.dumps(event, separators=(",", ":")).encode()
    ts = str(int(time.time()))
    sig = hmac.new(os.environ["FINANCE_PORTAL_SECRET"].encode(),
                   ts.encode() + b"." + body, hashlib.sha256).hexdigest()
    req = urllib.request.Request(
        os.environ["FINANCE_PORTAL_URL"] + "/api/v1/events", data=body, method="POST",
        headers={"X-FP-Key": os.environ["FINANCE_PORTAL_KEY"], "X-FP-Timestamp": ts,
                 "X-FP-Signature": sig, "Content-Type": "application/json"})
    return json.load(urllib.request.urlopen(req, timeout=20))

send({"event_id": "doc:INV/2627/00517", "type": "document.issued", "data": invoice})

import { createHmac } from "node:crypto";

export async function send(event) {
  const body = JSON.stringify(event);
  const ts = String(Math.floor(Date.now() / 1000));
  const sig = createHmac("sha256", process.env.FINANCE_PORTAL_SECRET)
    .update(`${ts}.${body}`).digest("hex");
  const res = await fetch(process.env.FINANCE_PORTAL_URL + "/api/v1/events", {
    method: "POST", body,
    headers: { "X-FP-Key": process.env.FINANCE_PORTAL_KEY, "X-FP-Timestamp": ts,
               "X-FP-Signature": sig, "Content-Type": "application/json" },
  });
  return res.json();
}

await send({ event_id: "doc:INV/2627/00517", type: "document.issued", data: invoice });

function send(array $event): array {
    $body = json_encode($event, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    $ts   = (string) time();
    $sig  = hash_hmac('sha256', $ts . '.' . $body, getenv('FINANCE_PORTAL_SECRET'));
    $ch = curl_init(getenv('FINANCE_PORTAL_URL') . '/api/v1/events');
    curl_setopt_array($ch, [
        CURLOPT_POST => true, CURLOPT_POSTFIELDS => $body, CURLOPT_RETURNTRANSFER => true,
        CURLOPT_HTTPHEADER => ['X-FP-Key: ' . getenv('FINANCE_PORTAL_KEY'), 'X-FP-Timestamp: ' . $ts,
                               'X-FP-Signature: ' . $sig, 'Content-Type: application/json'],
    ]);
    return json_decode(curl_exec($ch), true);
}

send(['event_id' => 'doc:INV/2627/00517', 'type' => 'document.issued', 'data' => $invoice]);