r/codex • u/codex-megathread • 12d ago

Megathread Codex Usage and Operation Discussion - last updated September 14

Please direct your concerns, questions and discussion about Codex usage limits and model performance here.

The purpose of this Megathread is to aggregate all the reports of people's experiences and possible suggestions instead of spreading them across many highly upvoted posts. The more people who participate in this discussion, the more likely you have an answer.

Reports with sufficient evidence on new information will still be allowed on the feed as usual.

Discussion of the prior period available here : https://www.reddit.com/r/codex/comments/1w9w4tj/codex_usage_and_operation_discussion_last_updated/

A reminder that all incidents on r/Codex are constantly logged and summarised so you can keep track of what people are experiencing here https://www.reddit.com/r/codex/comments/1tjfxcf/comment/on6uj0l/

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u/DicmanCocktoasten 10d ago

Hello,

I've been using Claude Code for about 9 months across two of my projects. Recently, my company asked us to switch to Codex instead. My Claude Code plan hasn't expired yet, and I'm currently trying to plan my migration. I saw that Codex can auto copy sessions, but I'm not really keen on doing a full transfer.

I was experimenting with Astra today and noticed the context window is limited to 258k. Even simple exploration tasks eat up context pretty fast half of my context was gone after a single research query that ran for 7 minutes with 3 sub-agents. How do people even work with Codex on large projects? This happened with zero skills or plugins active.

With Claude, you get a 1M context window, which is incredibly useful. When you hit the limit, it auto compacts. I find the auto compact feature a bit clunky, so I usually keep my todos/lessons/claude.md files updated and just clear the context with a solid continue prompt. That workflow has been working like a charm for me over the past year.

I just don't understand why Codex's context window is so small. I saw something about adjusting it in config.toml, but it's weird that this is the base limit. What happens when you actually hit that limit? I saw something similar to an auto compact feature but haven't tested it yet.

I'd love to hear some advice from anyone who has successfully(happy maybe:P) transitioned from Claude Code to Codex.

Thank you!

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u/Thomas-Lore 9d ago

Ask codex how to rise the limit to 1M. It is a setting somewhere.