export interface UserItem {
    id: string;
    username: string;
    password: string;
}
export declare class UsersService {
    private usersPath;
    constructor();
    private load;
    private save;
    list(): Promise<{
        id: string;
        username: string;
    }[]>;
    create(username: string, password: string): Promise<{
        id: string;
        username: string;
    }>;
    update(id: string, updates: {
        username?: string;
        password?: string;
    }): Promise<{
        id: string;
        username: string;
    }>;
    delete(id: string): Promise<void>;
    validateCredentials(username: string, password: string): Promise<boolean>;
    /** 根据用户名查找用户（用于登录后返回当前用户信息） */
    findByUsername(username: string): Promise<{
        id: string;
        username: string;
    } | null>;
    hasUsers(): Promise<boolean>;
    /** 确保缺省 admin 用户存在，若不存在则创建并保存。返回该用户的 { id, username } */
    ensureDefaultAdmin(): Promise<{
        id: string;
        username: string;
    }>;
}