Idempotência

KEY=$(uuidgen)   # guarde KEY junto da guia antes de chamar
for i in 1 2 3; do
  curl -s --max-time 15 https://api.sandbox.pagaki.com.br/v1/payments \
    -H "Authorization: Bearer $TOKEN" -H "Content-Type: application/json" \
    -H "Idempotency-Key: $KEY" \
    -d '{"method":"pix","amount":12550,"external_id":"guia-778899","payer":{"name":"Fulano de Tal","document":"12345678909"}}' \
    && break
  sleep $((i * 2))
done

use GuzzleHttp\Client;
use GuzzleHttp\Exception\ConnectException;

/** $key vem do seu banco: gravado junto do pedido antes da primeira tentativa. */
function createPix(Client $http, string $token, string $key, array $body): array
{
    for ($attempt = 1; ; $attempt++) {
        try {
            $response = $http->post('/v1/payments', [
                'headers' => ['Authorization' => "Bearer {$token}", 'Idempotency-Key' => $key],
                'json' => $body,
                'timeout' => 15,
                'http_errors' => false,
            ]);
        } catch (ConnectException $e) {
            if ($attempt === 3) {
                throw $e;
            }
            sleep($attempt * 2);
            continue; // mesma chave: se a primeira executou, vem a resposta dela
        }

        $status = $response->getStatusCode();
        if (in_array($status, [409, 429, 500], true) && $attempt < 3) {
            sleep((int) ($response->getHeaderLine('Retry-After') ?: $attempt * 2));
            continue;
        }

        return ['status' => $status, 'body' => json_decode((string) $response->getBody(), true)];
    }
}

/** key vem do seu banco: gravado junto do pedido antes da primeira tentativa. */
export async function createPix(token, key, body) {
  for (let attempt = 1; ; attempt++) {
    let response;
    try {
      response = await fetch('https://api.sandbox.pagaki.com.br/v1/payments', {
        method: 'POST',
        headers: { Authorization: `Bearer ${token}`, 'Content-Type': 'application/json', 'Idempotency-Key': key },
        body: JSON.stringify(body),
        signal: AbortSignal.timeout(15_000),
      });
    } catch (error) {
      if (attempt === 3) throw error;
      await new Promise((r) => setTimeout(r, attempt * 2000));
      continue; // mesma chave: se a primeira executou, vem a resposta dela
    }

    if ([409, 429, 500].includes(response.status) && attempt < 3) {
      const wait = Number(response.headers.get('Retry-After')) || attempt * 2;
      await new Promise((r) => setTimeout(r, wait * 1000));
      continue;
    }

    return { status: response.status, body: await response.json() };
  }
}