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Overview

Nelson excels at building complete applications. Whether it’s a REST API, a CLI tool, or a full-stack web app, Nelson can help you go from zero to working code.

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Building a REST API

Let’s walk through building a complete TODO API with Nelson.

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Step 1: Project Setup

You: Set up a new Node.js project for a REST API with Express and TypeScript
Nelson will:
  • Initialize package.json
  • Install dependencies (express, typescript, etc.)
  • Create tsconfig.json
  • Set up basic folder structure

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Step 2: Define the Data Model

You: Create a Todo type with id, title, completed, and createdAt fields

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Step 3: Implement Endpoints

You: Implement CRUD endpoints for todos:
- GET /todos - list all
- GET /todos/:id - get one
- POST /todos - create
- PUT /todos/:id - update
- DELETE /todos/:id - delete

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Step 4: Add Validation

You: Add input validation to the POST and PUT endpoints

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Step 5: Add Tests

You: Write Jest tests for all the endpoints

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Step 6: Verify Everything Works

You: Run the tests and make sure everything passes

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Building a CLI Tool

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Example: A File Organizer CLI

You: Build a CLI tool that organizes files in a directory by extension.
It should:
- Take a directory path as argument
- Create folders for each file extension
- Move files into their respective folders
- Have a --dry-run option to preview changes
- Use commander for argument parsing
Nelson will create a complete, working CLI tool.

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Building a Web App

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Example: A React Dashboard

You: Create a React dashboard with:
- A sidebar navigation
- A main content area
- A stats overview component
- A recent activity list
- Dark mode support using Tailwind CSS

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Using Nelson Loop for App Building

For complex apps, use Nelson Loop to let the AI iterate until everything works: 
/nelson-loop "Build a complete authentication system:

1. User model with email and hashed password
2. Register endpoint with validation
3. Login endpoint with JWT generation
4. Auth middleware for protected routes
5. Tests for all endpoints

Run tests after each implementation step.
Output <haha>AUTH COMPLETE</haha> when all tests pass." --completion-haha "AUTH COMPLETE" --max-iterations 30

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Tips for Building Apps

Start with Structure

Ask Nelson to set up the project structure first

Build Incrementally

Add features one at a time, testing as you go

Let Nelson Read

Before adding to existing code, let Nelson read the current files

Use Tests

Ask Nelson to write tests - they help verify the implementation

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Complete Example: Building a URL Shortener

Here’s how a full conversation might look: 
You: Build a URL shortener API with Node.js and Express

Nelson: HA-HA! A URL shortener? Let's make it good...

[Creates project structure]
[Implements URL model]
[Creates POST /shorten endpoint]
[Creates GET /:code redirect endpoint]
[Adds validation]
[Writes tests]

Done! Your URL shortener is ready. Here's what I built:
- POST /shorten - takes a URL, returns a short code
- GET /:code - redirects to the original URL
- Collision-resistant short codes
- Input validation
- Full test coverage

Try it: npm start, then POST to /shorten with {"url": "https://example.com"}