turbo-monorepo-test/README.md

# Ollis Turborepo Test

A full-stack TypeScript monorepo demonstrating modern development practices with automatic API client generation and type-safe end-to-end data flow.

## Architecture Overview

This monorepo showcases a **type-safe, auto-generated API contract** between backend and frontend:

```
Backend (Fastify) → OpenAPI Spec → Generated API Client → Frontend (SolidJS)
```

### Key Design Decisions

1. **Schema-First API Design**: Backend schemas (TypeBox/JSONSchema) are the single source of truth. The OpenAPI specification is automatically generated from these schemas and actual route definitions using Fastify's `@fastify/swagger`, ensuring the API contract always reflects the actual backend implementation.

2. **Automatic Client Generation**: The `api-client-backend` package uses `@hey-api/openapi-ts` to generate a fully typed API client from the OpenAPI spec, ensuring type safety across the stack.

3. **Turborepo Watch Mode**: Development workflow uses Turborepo's watch feature to orchestrate the entire pipeline automatically - when you change an API schema, the OpenAPI spec is regenerated, the client is regenerated, and the frontend picks up changes via HMR.

4. **Bare Metal Development**: Apps and packages run directly on the host machine (not containerized) for faster iteration, better debugging, and native tool integration. Only external dependencies like PostgreSQL run in Docker containers via `docker-compose`.

## What's inside?

This Turborepo includes the following packages/apps:

### Apps

- `frontend`: a [SolidJS](https://www.solidjs.com/) app with CRUD UI for persons and pets
- `backend`: a [Fastify](https://fastify.dev/) REST API with PostgreSQL and Kysely ORM

### Packages

- `@olli/api-client-backend`: Auto-generated TypeScript API client based on backend's OpenAPI spec
- `@olli/ts-config`: Shared TypeScript configurations

### Utilities

- [TypeScript](https://www.typescriptlang.org/) for static type checking
- [Biome](https://biomejs.dev/) for code formatting and linting
- [Kysely](https://kysely.dev/) for type-safe SQL queries
- [Vitest](https://vitest.dev/) for testing

## Development Workflow

### Initial Setup

1. **Copy environment files:**
```sh
cp .env.example .env
cp apps/frontend/.env.example apps/frontend/.env
cp apps/backend/.env.example apps/backend/.env
```

2. **Start local dependencies (PostgreSQL):**
```sh
docker compose up -d
```
- PGAdmin: http://localhost:5050

3. **Install dependencies:**
```sh
pnpm install
```

### Running Development Servers

The recommended way to develop is using Turborepo's watch mode:

```sh
pnpm run dev:watch
```

Or with global Turbo:
```sh
turbo watch dev:watch export-openapi generate
```
> `turbo watch` only works for non-persistent tasks. So `dev` tasks are not affected, therefore we need to run the `dev:watch` task here, so the apps actually watch changes by themselves.

#### What `dev:watch` Does

This single command orchestrates the entire development workflow:

1. **Starts Development Servers** (`dev:watch` task):
   - Backend: Runs on http://localhost:3000 with nodemon for auto-restart
   - Frontend: Runs on http://localhost:5173 with Vite HMR

2. **Watches for API Changes** (`export-openapi` task):
   - Monitors backend source files (`src/**/*.ts`)
   - When API schemas change, automatically exports updated OpenAPI spec to `packages/api-client-backend/openapi.json`

3. **Regenerates API Client** (`generate` task):
   - Watches the OpenAPI spec file
   - When spec changes, regenerates TypeScript client in `packages/api-client-backend/generated/`
   - Thanks to PNPM workspace linking, frontend immediately sees the updated types

4. **Updates Frontend** (automatic via Vite HMR):
   - Vite detects changes in workspace dependencies
   - Frontend auto-refreshes with new API types and methods

**The Flow:**
```
Backend code change
  ↓
Nodemon restarts backend server
  ↓
Turbo watch detects file change
  ↓
export-openapi script runs → generates openapi.json
  ↓
Turbo runs generate task → regenerates API client
  ↓
Vite HMR detects api-client-backend change
  ↓
Frontend reloads with updated types ✨
```

This workflow ensures **zero manual steps** - just change your API schema and watch it propagate through the entire stack!

### Alternative Development Commands

Develop all apps and packages:
```sh
turbo dev
```

Develop a specific package:
```sh
turbo dev --filter=backend
turbo dev --filter=frontend
```

### Build

Build all apps and packages:
```sh
turbo build
```

Build a specific package:
```sh
turbo build --filter=backend
```

### Testing

Run all tests:
```sh
turbo test
```

Run tests in watch mode:
```sh
turbo test:watch
```

## Project Structure

```
apps/
  backend/               # Fastify API server
    src/
      features/         # Feature-based organization
        demo/
          *.routes.ts   # API route handlers
          *.schema.ts   # Zod/TypeBox schemas
          *.repository.ts
      db/               # Database setup and migrations
    scripts/
      export-openapi.ts # OpenAPI spec generator
  frontend/            # SolidJS web app
    src/
      person-crud.tsx  # Person management UI
      pet-crud.tsx     # Pet management UI
      api.ts           # Configured API client
packages/
  api-client-backend/  # Generated API client
    generated/         # Auto-generated (don't edit!)
    openapi.json       # Source of truth from backend
```

## Useful Links

Learn more about the power of Turborepo:

- [Tasks](https://turborepo.com/docs/crafting-your-repository/running-tasks)
- [Caching](https://turborepo.com/docs/crafting-your-repository/caching)
- [Remote Caching](https://turborepo.com/docs/core-concepts/remote-caching)
- [Filtering](https://turborepo.com/docs/crafting-your-repository/running-tasks#using-filters)
- [Configuration Options](https://turborepo.com/docs/reference/configuration)
- [CLI Usage](https://turborepo.com/docs/reference/command-line-reference)