Chanjoong (CJ) Kim

Seoul

All projects

Oneline. One line in, a working tool on your phone.

When
Event
Google I/O Hackathon
Stack
Managed Agents, Playwright, Cloud Run, Python, Next.js
The Oneline dashboard: a one-line request at the top, and three candidates under it, one still building and two built.
Mid-⁠build: three strategies side by side.

Why

Describe the exact tool you need in one line, say an interval timer or this week's word flashcards, and get it running on your phone: small software for one person, with no app store in between.

How

Generated tools vary a lot, even for the same request, and a model asked to pick the best one reads the code without ever running it, so broken builds slip through. So three candidates build in parallel, each in its own sandbox. Scripted browser checks decide whether each one works, with no model judgment; a model scores only usability and design. Any candidate that fails the function checks drops out, and the winner deploys and opens on the phone from a QR code.

Oneline after judging: each candidate's function, UX and design scores and its final score, the winner marked, and its preview below.
One run of a tip calculator, judged: the green card won.
A phone showing Tip Splitter: the bill, the tip and the number of people filled in, and what each person pays.
The winner, a tip splitter, on a phone.

Outcome

I was selected for the hackathon in San Francisco and demoed Oneline live, with Q&A, before four industry judges. I built it with four Claude Code terminals, one per role.