REA Tutorial: Rebuild a Video Editor With Claude Code and AI

What if you could point an AI coding agent at a piece of software you like and say, “work out how this does it, then build me one”? That’s the idea behind REA, short for Reverse Engineer Anything. In this video I used it with Claude Code to rebuild a working video editor modelled on Kdenlive, the free open-source editor.

This guide explains what REA is, how to install it, how I used it in the video, what came out of a four-hour rebuild, and where people usually go wrong. I’m writing it from the video’s chapters and REA’s own website, so anything not shown in either is left out.

Prefer to watch? See the full walkthrough on YouTube. I build the whole thing on screen.

What is REA (Reverse Engineer Anything)?

REA describes itself as reverse engineering for your coding agent. Reverse engineering means learning how software works by inspecting the program itself rather than reading its documentation. REA gives your agent tools to do that: it can read the code, see what the program does while it runs, and then explain a feature or help you rebuild it.

The REA site describes a simple three-step loop:

• Ask about one feature. Give your agent a program or page and a question.
• Inspect the program. REA helps the agent read the code and watch it run.
• Explain it, then try a change. The agent uses what it found to explain or rebuild the feature.

The site’s own examples include working out why Windows Calculator gives 220 for 200 + 10%, finding the speed rule in the browser dinosaur game, and cloning a website. It also lists guides for native binaries, JavaScript and Electron apps, and browser and runtime activity, plus a way to turn a recorded web app session into an environment for training and testing AI agents.

If coding agents are new to you, my guide to building web apps in Claude Code covers the basics this video builds on.

Why rebuild a video editor?

Video editors are a hard test. There’s a timeline, media import, tracks, playback and a lot of interface controls that all have to work together. That’s why I picked one: if REA and Claude Code can get something like this working, smaller tools should be easy.

The model I chose was Kdenlive. Before starting, I went through its main features in the video so you can see what the rebuild was aiming for. Kdenlive is free and open source, so it’s a fair target to study, and it’s one of the free alternatives to Adobe I mention at the end of the video.

How to install REA

You can set REA up in two ways. Both come from the official site at rea.tools.

Option 1: ask your coding agent

Paste this prompt into your coding agent:

Install REA and connect it to this coding agent using npx rea-agents@latest setup. Show me the setup plan for approval, then verify the installation.

Option 2: run it in your terminal

This is the route I took in the video:

npx rea-agents@latest setup

Either way, approve the setup plan when it appears, then restart your agent so it can load REA’s tools. The site also lists a curl install option if you’d rather not use npx.

If you want help getting agent tools like this installed and connected, that’s what AI Income Lab is for. You can ask questions there while you build.

Using REA with Claude Code

Once REA was installed, I opened Claude Code and gave it the job. The video labels the model Claude Code 5.5. REA’s site suggests prompts in a set pattern: name the target, say “use REA to inspect” it, then say what you want back. For example, its website-cloning prompt is simply:

Use REA to inspect https://rea.tools/. Clone this website for me.

For a bigger project like a video editor, it’s worth giving the agent a clearer brief. Here’s how I’d build a prompt, following REA’s examples:

• Name the target app (here, Kdenlive).
• Ask it to inspect how the main features work: media import, the timeline and playback.
• Ask it to rebuild those features as a new app, then test them.
• Ask it to report what works and what doesn’t.

I show this on screen in the video, including the prompt and how Claude Code works through it.

What four hours produced

The rebuild took about four hours. Then I went through the AI-generated editor on camera. I imported media and tested the timeline to see how much of the core workflow held up.

It wasn’t perfect on the first pass. Some of the interface sliders didn’t behave properly, so I went back to Claude and had it fix them. That’s the normal pattern with agent-built software: the first version gets you most of the way, then you test, find what’s broken, and give the agent specific fixes.

I’m not claiming the result replaces Kdenlive. It’s a working editor built from scratch by an agent in an afternoon, and that’s the part that impressed me.

Want the prompts and templates for builds like this? They’re inside AI Income Lab, the AI Automation Station community.

What you can use REA for

A full video editor is the showy example, but the same approach works on smaller jobs. Based on REA’s own examples, you can use it to:

• Understand one feature. Ask why an app behaves a certain way, like the Calculator percentage example on REA’s site.
• Rebuild a feature with a twist. REA’s dinosaur-game demo finds the speed rule, then rebuilds it with a speed slider.
• Clone a website. Point it at a page and ask for a copy.
• Build test environments. Record a web app session and turn it into a local environment where agents can practise tasks.

For your own work, the practical angle is learning from tools you already use. If a free app does one thing you love, an agent with REA can show you how it works and help you build that into your own project.

Is it legal and fair to reverse engineer software?

This is worth thinking about before you start. I’m not giving legal advice. The safest targets are open-source projects like Kdenlive, where the code is public and the licence tells you what you can do with it. REA’s own examples note the licences of the code they inspect.

For closed-source software, read the licence and terms before you copy anything. Studying how a feature works is a different thing from shipping a copy of someone else’s product. When in doubt, use what you learn to build your own version rather than cloning it outright.

For another example of an agent rebuilding something end to end, see how I rebuilt my website in minutes using Codex. If you want agents working together on bigger projects, read how to build an AI operating system.

Common mistakes to avoid

• Forgetting to restart the agent. REA’s setup says to restart your agent after you approve the plan. If you skip this, the agent won’t have REA’s tools.
• Asking for everything at once. REA’s examples start with one feature and one question. For a big app, start with the core and add features in rounds.
• Skipping the testing. My editor needed slider fixes. Import real media, use the timeline, and give the agent specific bugs to fix.
• Expecting a finished product. Four hours got me a working editor, not a polished replacement for a mature open-source app.
• Ignoring licences. Pick open-source targets, or check the terms before you copy closed software.

If you get stuck at any of these steps, bring your question to AI Income Lab. That’s where members help each other with builds like this.

FAQ

Conclusion

REA gives a coding agent a new skill: looking inside software to see how it really works. Paired with Claude Code, that was enough to rebuild a working video editor modelled on Kdenlive in about four hours, with a round of fixes after testing. Start small with one feature in one app, test properly, and stick to targets you’re allowed to study.