/** 应用层错误：入口层据此转成协议里的 ErrorEnvelope（见 docs/spec/protocol.md 第 8 节） */
export class AppError extends Error {
  readonly code: string;
  readonly status: number;
  readonly retryable: boolean;

  constructor(code: string, message: string, options: { status?: number; retryable?: boolean } = {}) {
    super(message);
    this.name = 'AppError';
    this.code = code;
    this.status = options.status ?? 400;
    this.retryable = options.retryable ?? false;
  }
}

export const badRequest = (message: string): AppError => new AppError('invalid_request', message, { status: 400 });
export const notFound = (what: string): AppError => new AppError('not_found', `${what} 不存在`, { status: 404 });
export const conflict = (message: string, retryable = true): AppError =>
  new AppError('conflict', message, { status: 409, retryable });