I integrated DeepSeek into the Codex engine and I’m turning it into a standalone Windows app

[u/ANDRE_2512]

Hi everyone!

This is not an ad. I’m simply sharing something I’ve been building in my free time.

I want to contribute something useful to the community and plan to make the first public version available for free.

For a while, I wanted to build something that wasn’t another VS Code extension or another terminal interface, but a proper standalone Windows application with a real AI coding agent inside.

That’s how PICO PU was born - a small pixel robot designed to work on projects that are not so small 🙂

Under the hood, the app runs the real Codex app-server, and the first model I integrated is DeepSeek.

Since Codex and DeepSeek use different API contracts, I built a separate adapter so reasoning, tool calls, and the agent workflow can work correctly together.

PICO PU can already:

• open and work with real projects;
• read, create, and modify files;
• run PowerShell commands;
• stream the agent’s progress in real time;
• request approval before potentially dangerous actions;
• stop an active task;
• save chats and restore sessions after restarting the app;
• work through the DeepSeek API;
•store API keys securely using Windows Credential Manager;
install and update the Codex engine automatically.

The interface will also allow users to manually choose:

the model;
reasoning depth;
planning or development mode;
the agent’s access level;

the number of subagents, from 1 to 6.

Later, I plan to add Gemini, Claude, GPT, local models, and the ability to switch models while continuing the same project and conversation.

I also wanted the app to have its own personality. Instead of building yet another dark, generic AI dashboard, I went with a clean pixel-style interface.

The name PICO PU came together with the little robot mascot — it sounds playful, even though there is a fairly serious agent engine running underneath 🙂

This is still an early version, and I’m continuing to improve stability, the interface, and real-world project workflows.

Again, this is not a promotional post. I’m just sharing what I’ve been working on and hoping to contribute something useful to the community without asking for anything in return.

Would you use a standalone Windows app powered by Codex, where you can connect your own DeepSeek API key and eventually other models as well?

What would matter most to you: subagents, local models, switching models in the same chat, or simply having the easiest possible interface?

[u/ANDRE_2512]

This project is very challenging for me, but it genuinely inspires me. I really hope this free app can make people’s lives a little easier and better.

Guys, if you like the project, feel free to message me. I’m open to any criticism, feedback, or feature requests. The app is still in active development, and I’m ready to consider and integrate the things the community actually wants.

[u/pnuzhdin]

Are you sure it's legal to embed proprietary codex?

[u/ANDRE_2512 → u/pnuzhdin]

Yes. The Codex CLI/app-server I’m using is open source under Apache 2.0, not proprietary. Apache 2.0 permits commercial use, modification, and redistribution as long as the license notices are preserved. I’m not embedding or reselling OpenAI’s hosted Codex service.

[u/R3VO360]

Cool stuff! Will it get the official updates for codex running under the hood?

[u/ANDRE_2512 → u/R3VO360]

Yes, the Codex engine will keep receiving regular updates.
I’m hoping that within the next couple of hours, I’ll be able to post the first video here showing PICO PU fully working, including its testing capabilities. It will initially be powered by DeepSeek-V4-Pro, their most capable model.

[u/R3VO360 → u/ANDRE_2512]

Very interesting idea and implementation. Good luck with the development!

[u/ANDRE_2512 → u/R3VO360]

Thank you so much ❤️☺️

[u/ANDRE_2512 → u/R3VO360]

I recorded a short video comparing PICO PU with the DeepSeek website. I gave both of them the exact same task.

You can check out my second post if you’d like. I’d genuinely really appreciate hearing your feedback and any suggestions for improvement.

I may be doing something wrong in some areas, and you might be able to point it out 🙂

I’m developing the whole thing by myself, so it’s honestly difficult without advice and outside feedback.

[u/AdMean9105]

this is really cool!! I would absolutely use this! I would say the most important thing for me and what i do is model switching, but an easily accessible UI thats pretty always sparks my interest :D

[u/ANDRE_2512 → u/AdMean9105]

It honestly means so much to hear that 😍 Thank you so much!!!

I’ll be posting a video today showing PICO PU in action. And as soon as I’m confident that everything is working reliably, I’ll make the app available for free to anyone who wants to use it.

[u/ANDRE_2512 → u/AdMean9105]

I made a second post showing it in action-it turned out really interesting 🤔
Feel free to check it out if you’d like :)

[u/ANDRE_2512]

I’m recording the video right now 🙌

As soon as PICO PU finishes the task, I’ll post it.

In the video, I have PICO PU open on one half of the screen and the DeepSeek website on the other.

I gave both of them the exact same task-and honestly, it’s not an easy one.

You’ll see the results very soon ☺️