Cursor IDE: AI-First Coding

Cursor: The AI-Native Code Editor

Cursor is VS Code rebuilt with AI at the core — not as an add-on, but as the fundamental way you interact with code. For developers who want more than Copilot's inline suggestions, Cursor offers multi-file AI editing, deep codebase understanding, and an AI that can make changes across your entire project.

What Makes Cursor Different

GitHub Copilot suggests completions as you type. Cursor does that too, but it goes further:

Codebase-wide context: Cursor indexes your entire project so the AI understands how your files relate to each other. Ask "how is user authentication handled?" and it knows to look at middleware, auth utilities, and session handling across multiple files.

Multi-file edits: Ask Cursor to refactor a component, and it can modify the component file, its tests, the index file that exports it, and any files that import it — in one operation.

Cmd+K (inline edit): Select code, press Cmd+K, describe what to change — Cursor rewrites the selection in place. More precise than chat; faster than writing it yourself.

Agent mode: Give Cursor a task ("implement the user settings page with the form fields from our design spec") and it figures out which files to create and modify, executes the changes, runs tests if configured — with you reviewing and approving at each step.

Setup

1. Download from cursor.com
2. Import VS Code settings on first launch (your extensions, keybindings, and themes transfer automatically)
3. Add your project folder
4. Cursor indexes your codebase (takes 1-2 minutes for large projects)

Configure the AI model in Cursor Settings (Cmd+Shift+J):

• Claude Sonnet 4.5 (default, excellent for coding)
• GPT-4o (alternative)
• Claude Opus 4.7 (more powerful, slower, better for complex reasoning)

Core Workflows

Cmd+K: Inline Edit

The most-used Cursor feature. Select any code, press Cmd+K, type your instruction:

[Select a function]
Cmd+K → "add input validation — throw if email is invalid, if name is empty, if age is not between 0 and 150"

Cursor rewrites the selection with your changes applied. Review the diff, accept or reject.

Use Cmd+K for:

• Adding validation to existing functions
• Refactoring selected code to a different style
• Adding error handling
• Converting callbacks to async/await
• Translating between languages or frameworks

Cursor Chat (Cmd+L)

The chat panel with full codebase context.

Reference specific files with @:

@auth.ts How does session validation work? 
Is there anything that could fail silently?

@components/Button.tsx @components/Input.tsx 
Create a Form component that uses both of these components.
Add validation for required fields.

Reference the entire codebase with @Codebase:

@Codebase Where is database connection pooling configured? 
Is it handling connection limits correctly for a serverless environment?

Reference documentation with @Docs: Add documentation URLs in Cursor settings → it fetches and indexes them so you can ask "@NextjsDocs how do I configure rewrites in next.config.ts?"

Agent Mode

Agent mode is Cursor's most powerful feature — and the one that requires the most judgment about when to use it.

Best uses for Agent:

• Implementing a well-defined feature ("create the product listing page with filtering and pagination, matching the pattern in the course listing page")
• Adding a feature to an existing system with similar patterns
• Running tests and fixing failures iteratively

Be cautious with Agent for:

• Architectural decisions (let it execute, not design)
• Large refactors where you need tight control
• Anything touching authentication or security

Agent will ask for confirmation before making changes, but review its plan before approving.

CLAUDE.md: Teaching Cursor Your Codebase

Create a CLAUDE.md file in your project root (Cursor also uses CONTEXT.md or .cursor/rules):

# Project: Course Platform

## Tech Stack
Next.js 14 App Router, TypeScript strict, Tailwind CSS, 
Prisma + PostgreSQL, NextAuth.js v5, Stripe

## Key Conventions
- Server Components by default; add "use client" only when needed
- Database queries: use functions from /src/lib/db/ — never query directly in components
- All monetary amounts in cents (integer), never floats
- Use zod for all input validation at API boundaries
- Error handling: Server Components throw; API routes return structured errors

## File Structure
src/
  app/       — Next.js routes
  components/ — Reusable UI components
  lib/       — Utilities (db/, auth/, stripe/, email/)
  types/     — Shared TypeScript types

## Testing
Vitest + Testing Library. Run: npm test
Test files co-located with source: Button.tsx → Button.test.tsx

Cursor reads this file and applies your conventions automatically. This dramatically improves suggestion quality on domain-specific code.

Composer (Multi-File Creation)

For creating multiple related files at once:

Create the full data layer for a "Reviews" feature.
We need:
- Prisma schema additions for Review model (belongs to Course and User, has rating 1-5 and comment)
- Migration
- /src/lib/db/reviews.ts with createReview, getReviewsByCourse, getUserReview functions
- Type exports in /src/types/review.ts

Follow the same patterns as /src/lib/db/courses.ts

Composer shows you all the files it's going to create/modify, lets you review, then applies all changes at once.

Cursor vs. GitHub Copilot

Feature	Cursor	GitHub Copilot
Inline completions	Yes	Yes (similar)
Chat with codebase context	Deep	Basic
Multi-file editing	Yes	Limited
Agent mode	Yes	No
Editor requirement	Cursor (VS Code fork)	Works in any editor
Price	$20/month	$10/month
Best for	Serious development work	Quick completions, IDE flexibility

When to Reach for Cursor vs. Other Tools

Use Cursor for: Day-to-day coding, implementing features, refactoring, debugging with codebase context

Use Claude Code (CLI) for: Large refactors, running tests and fixing failures, tasks requiring command execution, when you want terminal-based workflow

Use ChatGPT/Claude for: Concepts and learning, tasks that don't require your specific codebase

Pricing

Free tier (limited AI calls), Pro ($20/month for most developers). Business plan for teams.

Next lesson: Claude Code review — using AI for thorough, systematic code review.