Refactor to Clean Architecture

Description

This skill guides the refactoring of tightly coupled NestJS services into a modular Clean Architecture structure. It separates business logic from infrastructure and ensures Dependency Inversion using abstract gateways.

When to use

Use this skill when:

• •Converting a "God Class" service (e.g., a service doing DB, API calls, and Logic) into Use Cases.
• •You see external libraries (axios, prisma, openai) imported directly into business logic.
• •You need to fix a module to match the project's "Golden Standard" (like the TagModule).

Instructions

1. •

   Analyze the Dependency Graph

   • •Identify external dependencies (Database, 3rd party APIs, File System).
   • •Identify business rules (validations, data transformations, flow control).
2. •

   Create Domain Layer (src/modules/<name>/domain/)

   • •Entities: Create pure TS classes defining the data structure. No decorators (unless absolutely necessary), no DB logic.
   • •Gateways (Interfaces): Define interfaces for every external interaction.
     • •Naming: I<Name>Repository for DB, I<Name>Gateway for external services.
     • •CRITICAL: Create a unique symbol or string constant for DI (e.g., export const IScraperGateway = Symbol('IScraperGateway');).
3. •

   Create Use Case Layer (src/modules/<name>/use-cases/)

   • •Create one file per action (e.g., process-article.use-case.ts).
   • •Inject dependencies using the Interface Token: @Inject(IScraperGateway) private readonly scraper: IScraperGateway.
   • •Constraint: NEVER import PrismaService, Axios, or LLMService here. Only imports from ../domain are allowed.
4. •

   Create Infrastructure Layer (src/modules/<name>/infra/)

   • •Create adapters that implement the Domain Interfaces.
   • •Naming: Prisma<Name>Repository, JinaScraperGateway, GeminiContentGenerator.
   • •Put all external libs here (Prisma, Axios, AI SDK).
5. •

   Wire the Module (src/modules/<name>/<name>.module.ts)

   • •Configure the providers array using provide (token) and useClass (implementation).
   • •Example:
     typescript

     {
       provide: IScraperGateway,
       useClass: JinaScraperAdapter
     }
     

Examples

Input: "Refactor the SearchService which uses duck-duck-scrape directly."

Output Plan:

1. •Create domain/gateways/search.gateway.interface.ts (Defines search(query: string): Promise<string[]>).
2. •Create infra/adapters/duckduckgo-search.adapter.ts (Implements interface, imports duck-duck-scrape).
3. •Update use-cases to depend on ISearchGateway.
4. •Update module.ts to bind ISearchGateway to DuckDuckGoSearchAdapter.