software-architecture

# Software Architecture ## Clean Architecture Layers ``` ┌─────────────────────────────────────────────┐ │ Frameworks & Drivers │ ← NestJS, TypeORM, Express ├─────────────────────────────────────────────┤ │ Interface Adapters │ ← Controllers, Repositories, Presenters ├─────────────────────────────────────────────┤ │ Application Layer │ ← Use Cases, Application Services ├─────────────────────────────────────────────┤ │ Domain Layer │ ← Entities, Value Objects, Domain Services └─────────────────────────────────────────────┘ Dependency Rule: outer layers depend on inner layers — NEVER the reverse. ``` ## Domain Layer ### Entities ```typescript // domain/user/user.entity.ts // Entities contain identity and business rules. No framework dependencies. export class User { private constructor( public readonly id: UserId, public readonly email: Email, private _name: string, private _role: UserRole, public readonly createdAt: Date, ) {} static create(props: { id: UserId email: Email name: string role?: UserRole }): User { if (!props.name.trim()) { throw new DomainError('Name cannot be empty') } return new User( props.id, props.email, props.name.trim(), props.role ?? UserRole.USER, new Date(), ) } get name(): string { return this._name } get role(): UserRole { return this....