"272k ought to be enough for anybody"
OpenAI reduces Codex Model Context Size from 372k to 272k
21–30 of 194 posts
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#22Another interesting change in that commit is the addition of this section to the system prompt: Before taking a destructive action: - Make sure the action is clearly within the user's request. - Resolve the exact targets with read-only checks when necessary. - Do not use `$HOME`, `~`, `/`, a workspace root, or another broad directory as the target of a recursive or destructive command Looks like the fix for this bug…
https://github.com/tekacs/fast-rm
I've overridden my rm with this, which I threw together for fast-deletes of things like Rust target/ directories, and after seeing the GPT horror story, I taught it to flatly reject deletions directly under `/` and under home directories, with a message printing the path that it's trying to delete.
Not exactly a perfect mitigation, but given that the stated risk was the model mistakenly using the wrong $HOME, it seems like a reasonable safety. I should probably make it use an even scarier rejection notice, though.
I also... have backups.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#23I never felt that context size was any issue at all in codex. I don't know how their compaction works, but it just keeps on going as if it has no context limit at all. At least in my experience.
For me, Codex regularly forgets to complete its last task when compaction occurs, especially when the last message I sent was right before compaction.
I’ve noticed it having weird message dropping and replay in general, but the compaction boundary has been pretty solid.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#24I am wondering why the codex repo is open source ? Can they afford it to be open source in the longer run ?
Not much point making it closed source at this point, coding agent harnesses are trivial to reverse-engineer.
Being open source was also a useful community lever they could pull when they were trying to catch up with Claude Code.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#25The other day I was trying to find out exactly how much context size 5.6 has in codex CLI (via subscription) and I didn’t find that documented in any of the obvious places. Sort of ridiculous that we have to find this out in X or Reddit, e.g: https://www.reddit.com/r/codex/s/hVv29obfFD
You can run ’codex debug models' into jq!
I forget whether it's documented or not, and it is kind of annoying that that's how you find it, but it does tell you. Maybe useful for the future if nothing else.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#26I know a lot of people like to say that compaction makes this moot, but the level of detail you lose across compaction is wildly too much for most things that I do, unfortunately.
Perhaps if your plans don't have as much detail, or if you're not, for example, having a discussion with a lot of nitty-gritty then it's fine?
The lack of long context is the main reason that I still end up using Anthropic.
The worst is when you need it to hold for example a number of papers in its head, or large and complex materials that it needs full resolution on and your context window ends up being perennially at 16%. You have about five minutes of conversation and it compacts and then you have to wait for it to read that again, get to 16%... and repeat.
372 was not perfect, but it was so much better and a godsend. It turned that 12 to 20% into more like 40%.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#27Codex compaction is really quite good. Smaller context doesn't really harm me.
I had a /goal running last night for 9.5 hours straight while I slept. When I woke up in the morning it was fully on task and focused.
Write up a detailed design doc. Build a decent AGENTS.md, and write up a good prompt or /goal.
Long context can be more of a curse than a benefit sometimes anyways.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#28Not a fan of their context compaction and I feel like 1M-token context should minimum today. Each day I see how GPT 5.5 and 5.6 struggle a bit after each compaction before they get to the full speed, sometimes focusing too much on some older steering message that made it into the compacted context.
Full agreement. I sincerely hope that reducing token is mostly a cost saving measure and not some roundabout way to get more token use. It still does not help. In my corp, bean counters rendered initially useful internal llm largely pointless as they severely limited context.
I swear there is a executive convention out there sharing worst practices.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#29I never felt that context size was any issue at all in codex. I don't know how their compaction works, but it just keeps on going as if it has no context limit at all. At least in my experience.
> 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…
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.
Re: OpenAI reduces Codex Model Context Size from 372k to 272k
#30I am wondering why the codex repo is open source ? Can they afford it to be open source in the longer run ?
What do you mean “afford”?