Idempotency

import { randomUUID } from "node:crypto";

const key = randomUUID(); // one key for this contract, reused on every retry

async function sendOnce(body) {
  for (let attempt = 0; attempt < 5; attempt++) {
    const res = await fetch("https://api.econtract.online/api/v1/contracts/send", {
      method: "POST",
      headers: {
        Authorization: `Bearer ${process.env.ECONTRACT_API_KEY}`,
        "Content-Type": "application/json",
        "Idempotency-Key": key,
      },
      body: JSON.stringify(body),
    }).catch(() => null); // network error: retry with the same key

    if (res?.ok) {
      if (res.headers.get("Idempotent-Replayed") === "true") console.log("replayed");
      return res.json();
    }
    const err = res ? await res.json() : { code: "NETWORK" };
    const retry = !res || [429, 502, 503, 504].includes(res.status) || err.code === "IDEMPOTENCY_IN_PROGRESS";
    if (!retry) throw new Error(`${err.code}: ${err.message}`);
    await new Promise((r) => setTimeout(r, 2 ** attempt * 1000));
  }
  throw new Error("gave up");
}

import os
import time
import uuid
import requests

key = str(uuid.uuid4())  # one key for this contract, reused on every retry

def send_once(body):
    for attempt in range(5):
        try:
            res = requests.post(
                "https://api.econtract.online/api/v1/contracts/send",
                headers={
                    "Authorization": f"Bearer {os.environ['ECONTRACT_API_KEY']}",
                    "Idempotency-Key": key,
                },
                json=body,
                timeout=120,
            )
        except requests.RequestException:
            time.sleep(2 ** attempt)  # network error: retry with the same key
            continue
        if res.ok:
            return res.json()
        err = res.json()
        if res.status_code not in (429, 502, 503, 504) and err.get("code") != "IDEMPOTENCY_IN_PROGRESS":
            raise RuntimeError(f"{err.get('code')}: {err.get('message')}")
        time.sleep(2 ** attempt)
    raise RuntimeError("gave up")