/** PostgreSQL unique_violation (23505), including Drizzle's wrapped cause shape. */
export function isPostgresUniqueError(error: unknown): boolean {
  let current: unknown = error;
  for (let depth = 0; current && depth < 5; depth += 1) {
    if ((current as { code?: string }).code === "23505") return true;
    current = (current as { cause?: unknown }).cause;
  }
  return false;
}