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.

If you aren't hiring junior engineers to do these kinds of things, where do you think the senior engineers you need in the future will come from?

My kid recently graduated from a very good school with a degree in computer science and what she's told me about the job market is scary. It seems that, relatively speaking, there's a lot of postings for senior engineers and very little for new grads.

My employer has hired recently and the flood of resumes after posting for a relatively low level position was nuts. There was just no hope of giving each candidate a fair chance and that really sucks.

My kid's classmates who did find work did it mostly through personal connections.

This is a bit of a game theory problem. "Training senior engineers" is an expensive and thankless task: you bear essentially all the cost, and most of the total benefit accrues to others as a positive externality. Griping at companies that they should undertake to provide this positive externality isn't really a constructive solution.

I think some people are betting on the fact that AI can replace junior devs in 2-5 years and seniors in 10-20, when the old ones are largely gone. But that's sort of beside the point as far as most corporate decision-making.

That sounds like a dangerous bet.

As I see it, it's actually the only safe bet.

Case 1: you keep training engineers.

Case 1.1: AGI soon, you don't need juniors or seniors besides a very few. You cost yourself a ton of money that competitors can reinvest into R&D, use to undercut your prices, or return to keep their investors happy.

Case 1.2: No AGI. Wages rise, a lot. You must remain in line with that to avoid losing those engineers you trained.

Case 2: You quit training juniors and let AI do the work.

Case 2.1: AGI soon, you have saved yourself a bundle of cash and remain mostly in in line with the market.

Case 2.2: no AGI, you are in the same bidding war for talent as everyone else, the same place you'd have been were you to have spent all that cash to train engineers. You now have a juicier balance sheet with which to enter this bidding war.

The only way out of this, you can probably see, is some sort of external co-ordination, as is the case with most of these situations. The high-EV move is to quit training juniors, by a mile, independently of whether AI can replace senior devs in a decade.

You’re looking at it from the point of view of an individual company. I’m seeing it as a risk for the entire industry.

Senior engineers are already very well paid. Wages rising a lot from where they already are, while companies compete for a few people, and those who can’t afford it need to lean on AI or wait 10+ years for someone to develop with equivalent expertise… all of this sounds bad for the industry. It’s only good for the few senior engineers that are about to retire, and the few who went out of their way to not use AI and acquire actual skills.