/** UUID v4 for operation identifiers; retries keep the caller's existing key. */
export function createOperationKey(): string {
    const secureRandom = globalThis.crypto;
    if (typeof secureRandom?.randomUUID === 'function') return secureRandom.randomUUID();
    if (typeof secureRandom?.getRandomValues !== 'function') {
        throw new Error('O navegador não disponibiliza geração criptográfica segura. Reabra o portal no endereço HTTPS configurado.');
    }
    const bytes = secureRandom.getRandomValues(new Uint8Array(16));
    bytes[6] = (bytes[6] & 0x0f) | 0x40;
    bytes[8] = (bytes[8] & 0x3f) | 0x80;
    const hex = Array.from(bytes, byte => byte.toString(16).padStart(2, '0')).join('');
    return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`;
}