A Research Preview of Codex

Some engineers on my team at Assembled and I have been a part of the alpha test of Codex, and I'll say it's been quite impressive.

We’ve long used local agents like Cursor and Claude Code, so we didn’t expect too much. But Codex shines in a few areas:

Parallel task execution: You can batch dozens of small edits (refactors, tests, boilerplate) and run them concurrently without context juggling. It's super nice to run a bunch of tasks at the same time (something that's really hard to do in Cursor, Cline, etc.)

It kind of feels like a junior engineer on steroids, you just need to point it at a file or function, specify the change, and it scaffolds out most of a PR. You still need to do a lot of work to get it production ready, but it's as if you have an infinite number of junior engineers at your disposal now all working on different things.

Model quality is good, but hard to say it's that much better than other models. In side-by-side tests with Cursor + Gemini 2.5-pro, naming, style and logic are relatively indistinguishable, so quality meets our bar but doesn’t yet exceed it.

It looks we are in this interesting cycle: millions of engineers contribute to open-source on github. The best of our minds use the code to develop powerful models to replace exactly these engineers. In fact, the more code a group contributes to github, the easier it is for the companies to replace this group. Case in point, frontend engineers are impacted most so far.

Does this mean people will be less incentivized to contribute to open source as time goes by?

P.S., I think the current trend is a wakeup call to us software engineers. We thought we were doing highly creative work, but in reality we spend a lot of time doing the basic job of knowledge workers: retrieving knowledge and interpolating some basic and highly predictable variations. Unfortunately, the current AI is really good at replacing this type of work.

My optimistic view is that in long term we will have invent or expand into more interesting work, but I'm not sure how long we will have to wait. The current generation of software engineers may suffer high supply but low demand of our profession for years to come.