Exploring Project Structure

Welcome to the first lesson of our course, Vibe Coding with Codex - Build a Full-Stack Next.js Task Manager. In this course, you’ll grow a minimal Next.js App Router project into a fully-featured Task Manager API. Before we write any backend logic, the goal of this unit is much simpler: get comfortable with Codex, learn how to talk to it, and explore your project safely. Think of this lesson as a warm-up that teaches you the habits you’ll rely on throughout the course.

Codex is the built-in AI assistant inside the CodeSignal IDE. It can read files in your project, explain code, create new files, update existing ones, and help you plan your work. Unlike a general chat model, Codex is tightly integrated with the filesystem—meaning it can only interact with files when you explicitly allow it.

Codex works best when you treat it as a junior engineer: reliable, fast, and helpful, but dependent on clear instructions. You stay in control; Codex executes your plan.

Although the CodeSignal environment already includes Codex integration, it’s useful to understand how Codex is typically set up outside this course. This gives you context for how the tool works under the hood and helps you build mental models that apply beyond the playground.

To install and run Codex locally, you would normally perform the following steps:

npm install -g @openai/codex

Then you would configure your API key:

export OPENAI_API_KEY="your-api-key"

After that, you would start interacting with the Codex CLI:

codex

This opens an interactive session similar to the one you’ll experience inside CodeSignal. You can issue read-only commands, request file edits, and generate new scaffolding. While you won’t run these commands directly in this course environment, understanding the setup helps clarify how Codex integrates with real-world development workflows.

Throughout the course, you’ll use Codex to perform several types of actions:

Read-only exploration
You can ask Codex to summarize what your files do, or explain unfamiliar concepts—without changing anything.

Targeted file edits
Codex can update specific files when instructed. Your prompt must say exactly which file(s) it is allowed to change.

File creation
As the project grows, you’ll ask Codex to create new route handlers, service modules, repository interfaces, and more.

Planning tasks
Codex is also useful for non-code conversations: outlining ideas, describing architectural steps, or drafting a roadmap.

Good prompts are precise and bounded. They explain what to do, where to do it, and what the final result should look like. You’ll practice this style throughout the step-by-step exercises.