HandRoll

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Inspiration

HandRoll was inspired by the desire to excel. It inverts the usual agentic workflow and promotes that the user engage with code directly.

What it does

HandRoll is a micro-IDE that lives inside Codex/ChatGPT as a "ChatGPT app". It provides a minimal, barebones text editor with agentic feedback and COT. Unlike most vibe coding tools, which directly author generative code, HandRoll instead challenges the user to write out scripts, providing rich next-line suggestions and expert chain of thought.

How we built it

I built the app with Codex over the course of a week. It's actually designed to compose directly into Codex itself as an MCP app.

Challenges we ran into

Perfecting the MCP roundtrip was surprisingly hard. I grappled with the new sites feature and spent considerable time and budget getting GPT 5.6 to boost development to the current state.

Accomplishments that we're proud of

Hand-rolling an RNN without external reference within Codex was super cool! I'm proud of how well the app composes into the existing ChatGPT ecosystem and how it acts as a "smart text editor," enabling the user to seamlessly learn from the model in real-time.

What we learned

I think the biggest lesson was: find the app you want to build. I was initially inspired by education/edutech and wanted to make a powerful memorization app that utilized techniques from pretraining and RLHF for individual learners. I faithfully executed on that idea, realized it was joyless, and opted to make a better tool. The agentic COT as "teacher" for a human "learner" was the one idea I salvaged, and I think it stands.

What's next for HandRoll

I'd like to see HandRoll even more closely integrated into the ChatGPT apps ecosystem. Having a native, simple, 100% seamless IDE for code that works directly within Codex is a dream. I have a lot of work to do toward achieving that end, but if the project finds support, I will make that a north-star goal.

Built With

• codex