> I never felt that context size was any issue at all in codex.

I'm guessing you just started using codex, it suffered greatly from "model context size exceeded" errors early on, where compaction couldn't even recover from it, these errors just stopped happening maybe some month(s) ago.

Nowadays it's a lot better though and I've don't get stuck in those anymore. Although I don't like the idea that they don't surface what goes into the "concise summary" afterwards, make it really hard to know if it actually got everything important or not.

In general, codex seems to be moving into the way of hiding as much from the user as possible, and it wouldn't surprise me if they eventually start encrypting the entire session logs just like they did with agent>sub-agent prompts recently. Sad though as it's easily the best harness+model combo available today out of the ones I've tried.

That has nothing to do with context window or the models at all; it's the compute capacity.

Pretty much every single AI firm had the same issue when the new model came out, it's the result of everyone jumping onboard and consuming all available compute capacity to break it for days.

Claude had the same issues when they released their newer models.

Claude also had issues with this kind of thing for months early on, too, where it simply couldn't compact its own emissions.

But definitely earlier GPT models suffered greatly as context got large, and the compaction itself in Codex was really crappy. That changed around January.