const Int64String: brand(
  "Int64String",
  NonEmptyTrimmedString,
  (value) => {
    const negative = value.startsWith("-");

    if (
      value.length > (negative ? 20 : 19) ||
      !/^(?:0|-?[1-9]\d*)$/u.test(value)
    ) {
      return err<Int64StringError>({ type: "Int64String", value });
    }

    const digits = negative ? value.slice(1) : value;
    const max = negative ? "9223372036854775808" : "9223372036854775807";

    return digits.length < 19 || digits <= max
      ? ok()
      : err<Int64StringError>({ type: "Int64String", value });
  },
  (error) =>
    `The value ${safelyStringifyUnknownValue(error.value)} is not a valid Int64 string.`,
);