interface User {
  id: string;
  name: string;
}

function isUser(value: unknown): value is User {
  if (typeof value !== "object" || value === null) return false;
  const o = value as Record<string, unknown>;
  return typeof o.id === "string" && typeof o.name === "string";
}

async function loadUser(id: string): Promise<User> {
  const res = await fetch(`/api/users/${id}`);
  if (!res.ok) {
    throw new Error(`HTTP ${res.status}`);
  }
  const raw: unknown = await res.json();
  if (!isUser(raw)) {
    throw new Error("Неверный формат ответа");
  }
  return raw;
}