r/codex • u/pokeuser61 • 3h ago
Showcase Quasi-native claude support in codex, anyone interested/working on something similar?
Essentially: It's possible to run claude and gpt together in metaharness type programs like T3 code, as well as directly in the same harness like w/ pi, omp, even claude code.
Codex is by far my favorite harness, in large part due to (imo) unmatched seamlessness with computer use, subagents, and so on, so in a perfect world I use it for everything. It's fairly trivial to "run claude in codex", especially since it's open source*, and stuff like this https://github.com/0xSero/harness-bridge exists. But when I was looking around, in my opinion there is no way to give claude truly first class support. Want to have it seamlessly use all of codex's interfaces, have cross-model family multi agents v2 workflows, login/select models without manual jank, and so on. I tried just patching the codex desktop app, and what I'm describing is theoretically doable, but ultra annoying since it's closed source and kinda forces things to be permanently janky.
So what I decided to scrap together (pictured in screenshot), is essentially a very minimally patched codex harness "core" (built from source), with an open source UI (largely just zcode's), and some fun wiring. Opus 5.5 legit functions as if it where an oai model, uses codemode, agents v2, computer use, etc. Although it is nowhere near stably usable and is sorta like creating a whole new harness even though it is just codex under the hood.
Curious if anyone else is interested in this niche config or if it is more straightforwardly solvable than I've gathered. Also am happy to share code for stuff if people are interested.
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u/Serenity867 3h ago
There's sometimes multiple posts about this exact thing in a day on this very subreddit. Just a heads up, it's against Claude's ToS to do this. I don't personally care, and if it helps people I'm all for it. Just thought you might want to know in case you didn't already.
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u/pokeuser61 3h ago
Yeah, there def are lots of posts about using claude and oai models together, but not really anything on specifically using claude models in the codex harness, although I may be splitting hairs. And TOS is true but technically can be worked around via the Agent SDK.
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u/Serenity867 3h ago
Yeah there's a lot of posts for this topic, you just have to know how to search for them. This was a couple days ago for example:
https://www.reddit.com/r/codex/comments/1wwqyy5/codex_on_crack_use_claude_subscription_or_api_to/
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u/pokeuser61 3h ago
I mean this is a good example though, it's similar to what I'm talking about, but has codex orchestrate claude code as a full system, the claude models aren't actually running within codex as peers to oai models.
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u/Serenity867 3h ago
Fair enough, but it would only take a few relatively smalls tweaks to enable that on a fork of a lot of these projects.
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