# MercadoDeVida backend — modular monolith skeleton

TypeScript + Fastify modular monolith. Simple code, clear modules, small changes, no magic.

## Requirements

- Node.js >= 22
- npm

## Commands

```bash
npm install           # install dependencies
npm run build         # compile to dist/
npm start             # run compiled server (PORT, HOST env vars)
npm test              # vitest unit/integration tests
npm run typecheck     # tsc --noEmit
npm run lint          # eslint + prettier check
npm run lint:boundaries  # module boundary check
```

## Layout

```text
src/
├── app/             # composition root (only place that wires modules)
├── infrastructure/  # http server entrypoint (later: db, redis, providers)
├── modules/         # business modules, one folder each
│   └── health/      # exemplar module: public API only via index.ts
└── shared/          # cross-cutting helpers (error envelope)
```

## Module rules

- A module exposes its public API only through its `index.ts`.
- Files inside a module may import: own subtree, `src/shared`, Node builtins, npm packages.
- Code outside modules (app/infrastructure) may import a module only via its `index.ts`.
- `npm run lint:boundaries` enforces these rules.