Summary  
This chapter covers treating a substantial feature addition as a mini project by entering a planning phase—using AI planning mode to outline required file and UI changes and logic—reviewing that plan before implementing and testing the code.  

General domain of usage  
application development

You know how to make small changes. This chapter is about what to do when the feature you want to add is more substantial.

The approach is simple: treat it like a mini version of how you started the whole project. Plan first, then build.

### Why bigger features need a plan

Small changes like updating a colour or tweaking a field can be done with a direct prompt. But when a feature involves multiple files, new logic, or changes to how the app behaves, jumping straight to building often creates problems.

Going back to plan mode first means Claude Code thinks through what needs to change before it touches anything. You get to review that plan and catch anything that does not match what you wanted before a single line of code is written.

Treat every significant new feature like a mini project. Plan it, approve it, then build it.

Note

Click the model selector in Claude Code and switch to Plan Mode. This tells Claude Code to think through the implementation and return a plan rather than immediately writing code.

1. Switch to plan mode

You do not need to be perfectly specific at this stage. Describe the feature in plain English. Claude Code may ask clarifying questions. If it does, answer them. If it does not, read through the plan carefully before approving.

2. Describe what you want

Check that what Claude Code is proposing matches what you actually want. Look at which files it plans to create or modify. If something looks off, tell it before approving.

3. Review the plan

Once the plan looks right, approve it and switch back to a normal session. Claude Code will build the feature out from there.

4. Approve and build

Try the feature in your browser as soon as it is done. Does it behave the way you expected? If not, write a specific follow-up prompt describing the one thing that needs adjusting.

5. Test it

Why is it important to plan before building a significant new feature?

Build and launch a real app in just one weekend using modern AI tools and a simple, practical workflow, using Claude Code to plan, generate, and refine your code, managing your project with GitHub, and deploying your finished app online with Vercel. You’ll start with an idea and quickly turn it into a clear project plan, then move step by step into building a working application, focusing on core features, simple architecture, and fast iteration instead of unnecessary complexity, while learning how to work effectively with AI by writing better prompts, fixing errors, and improving features, ending with a live app, a clean GitHub project, and a repeatable system for turning future ideas into real products faster.

Understand the basics of AI-assisted development, set up your environment, and get familiar with Claude Code before starting your first app.

Turn your idea into a clear, simple plan and define the smallest version of your app that delivers real value.

Go from zero to a running app by generating code with AI, setting up the project, and understanding what was created.

Improve your app by adding features, refining the design, and learning how to fix issues effectively.

Publish your project, make it accessible online, and ensure everything works using GitHub and Vercel.

Adding New Features

Why bigger features need a plan

The process