Архитектура TypeScript-кодовой базы

export class SqlUserRepository {
  constructor(
    public readonly pool: Pool,
    public readonly mapper: OrmMapper
  ) {}
  find(id: UserId): Promise<User | undefined> { /* ... */ }
}

const api = {
  load(id: string) { return Promise.resolve(id); },
  version: "v1"
} satisfies PublicApi;

// index.ts
export * from "./service";

// order-domain needs to store an order
// sql-adapter knows database details

type User = Prisma.User;

const repository = new SqlUserRepository(pool);
const service = new UserService(repository);

try {
  await db.insert(order);
} catch (error) {
  throw error;
}

type ReserveResult =
  | { ok: true; reservation: Reservation }
  | { ok: false; reason: "sold_out" | "invalid_period" };

if (error instanceof VendorTimeoutError) { /* ... */ }

// было
createUser(name: string)
// стало
createUser(name: string, locale: string)

createUser({ name, locale: "ru", notify: true });

/** @deprecated Use createUser(options) */
export function createLegacyUser(name: string): User;

interface UserReader { find(id: UserId): Promise<UserSummary | undefined>; }
declare class SqlUserRepository {
  find(id: UserId): Promise<UserSummary | undefined>;
  runRawSql(sql: string): Promise<unknown>;
}
declare const repo: SqlUserRepository;
const reader: UserReader = repo;

declare const reader: UserReader;
// @ts-expect-error — сырой SQL не входит в порт
reader.runRawSql("select 1");

interface PaymentGateway { charge(req: ChargeRequest): Promise<ChargeResult>; }
class StripeGateway implements PaymentGateway {
  async charge(req: ChargeRequest): Promise<ChargeResult> { /* ... */ throw new Error(); }
}

export interface CreateUserOptions {
  name: string;
  locale?: string;
  notify?: boolean;
}
export function createUser(options: CreateUserOptions): Promise<UserSummary>;

export type FindUserResult =
  | { ok: true; user: UserSummary; entity: OrmUserEntity }
  | { ok: false; reason: "not_found" };

type ChargeResult =
 | { kind: "approved"; id: TransactionId }
 | { kind: "declined"; reason: string }
 | { kind: "rate_limited"; retryAfterMs: number };