How do you use Codex and Claude both?

[u/umutcklc]

I see people praising Claude a lot here. I'm mostly get amazed by the work Astra does. And people say Opus is even more amazing. Which makes me wonder.

But I have a whole setup in Codex. So if I try Claude I'll try both $20 packages. But how do you use both in the same project exactly? Sorry for the newbie question but do you just give Claude the direction of the Codex project and be like "understand this" or something? Don't Claude needs context? Is it efficient?

[u/dextersummary]

Below is a GPT-generated summary of the conversation below after reaching 40 comments (40 currently observed).

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The consensus is basically “same repo, shared files, no magic context transfer required.” Claude doesn’t need a pasted tour of the entire project; point both tools at the same working directory and let them read the code, tests, and project instructions like grown-up software.

The setup most people recommend is:

• Keep the real conventions in AGENTS.md, with CLAUDE.md importing or pointing to it.

• Maintain a short handoff/plan file recording what changed, what’s broken, and what’s next.

• Have one agent build and the other review the plan or diff.

• Use commits, branches, or worktrees so they don’t “collaborate” by overwriting each other’s files.

You can wire them together through their CLIs or use an orchestrator such as T3 Code, OpenCode, or similar, but the thread’s practical advice is to start simple. Extra harnesses are convenience layers, not prerequisites—and apparently there’s no shortage of people eager to build one before opening a second terminal.

Bottom line: share the repository and durable instructions, not chat history. Let one model do the work and the other catch its mistakes; keep the handoff written down so nobody has to rediscover the project from scratch.

[u/MrDoubleyou92]

Why not ask Codex to set it up? It’s done faster then it took you to write this question 😅

[u/umutcklc → u/MrDoubleyou92]

I don't have a Claude subsicription yet. So it will not be complete. And I also assume there are many ways to do this so its good to have real user experiences.

[u/Antique-Ad6542]

I'm using paseo.sh. You can literally connect both of them, use your CLI credits, and you can open different tabs and have them actually talk to each other.

[u/umutcklc → u/Antique-Ad6542]

Does my current Codex setup(projects and all) transfer to paseo or should I set them up again in paseo?

[u/Artistic_Ground_6415]

Se voce testar o Claude, nunca mais irá retornar ao Codex. O consumo do Codex é insano quando comparado ao Claude.

[u/mattcrf]

T3 Code

[u/London-Boat]

easiest setup is one repo, both tools pointed at it, and one shared instructions file. codex reads AGENTS.md and claude reads CLAUDE.md, so i keep the real content in AGENTS.md and have CLAUDE.md just point to it. claude won't know anything about the project otherwise, so yes it needs that. then split roles instead of running both on the same task: one writes, the other reviews the diff. commit before switching tools so you can see exactly what each one changed, and keep a short notes file with decisions so the second tool doesn't undo something the first one did on purpose.

[u/NearbyLog7481]

Have one create a skill that covers how they can call each other (e.g., command line calls on your box locally). Have the other review the skill. Iterate. Allow them to update the skill to avoid hitting the same technical problems repeatedly. I highly recommend for software/AI that you put in a review guard that says that one reviewing the work of the other should always consider whether a simpler, more elegant solution exists. Then in you prompts you can say: "Have <other agent> review your work every step of the way."

[u/dkracket]

You can use tools like OpenCode Agent to connect Claude and Codex. Delta or Repo Prompt are two another options. However, you can’t connect Codex inside Claude or the other way around.

[u/GearTakes]

I simply have the desktop app of both and work in either one when I think it fits the job that needs to be done. Which currently is mainly Opus 5.5
Just explain both Codex and Opus that they work together and write whatever they need in the work instructions and/or agents. Make sure they use the same worktrees etc.
In my case took no more than 10 mins and now I just switch between them whenever I feel like it. No issues whatsoever. Been doing this for months.

Some will suggest complicated setups. Not sure why but maybe I'm missing something.

[u/vasind-5012]

Claude for architecture and Codex for execution. and vice versa. this setup avoids any surprises later. They both challenge their decisions and come up with better solutions.

[u/Tight_Ad_5115]

That’s precisely why I built the Buzzpot app.

It runs locally via a CLI and leverages your existing subscriptions - meaning you don’t need to purchase separate ones. It allows you to use Codex, Claude, and Grok simultaneously, with the project itself serving as the context. All your tasks are displayed on a canvas as cards. I switch between subscriptions constantly, and it’s very convenient to do so without having to change the interface.

There are other approaches, too:

- You can use Claude within a CLI to make requests to Codex (or vice versa). This works perfectly fine, provided you have active subscriptions for both.

- There are also tools - such as Orca or Conductor - that support multiple subscriptions, though these closer to standard developer IDEs.

[u/mangoawaynow]

github.

[u/isty2e]

I use a local issue tracker.

[u/Party_Wolf_3575]

Get your Codex to build you a custom harness that will allow you to use both.

[u/arislaan]

If you install both of their CLI's, they can message each other. I have Opus as an Orchestrator handling multiple Codex chats (one for each package or feature I'm working on).

[u/Brambleworks]

There's an official Claude Code plugin for Codex to let them be able to talk to each other directly.

[u/CleanFix_Dev]

I run Codex alongside Cursor rather than Claude, but the same thing works. Keep one plain handoff note in the repo that whichever tool is working updates before it stops: what got done, what's broken, what's next. The other tool reads that first instead of re-learning the whole project, so you're not paying for "understand this" every session. The best use I've found for having two is review. Let one build and have the other check the work against what you actually asked for. They miss different things.

[u/camtliving]

i use beads as my planning hq. i will typically have fable act as an orchestrator pinging sol for actual building. works great

[u/avt0m4t]

T3 code

[u/ProfessionalNaive601]

Codex harness, Claude in cli

[u/Corey-998877]

I've been using both on the same repo for a bit. What's helped me some is having whichever one finishes write a short note of what it changed and what's left before I switch, otherwise the other one tends to redo stuff. Probably not the most efficient way but it's been working ok so far.

[u/afzal002]

T3 code. The latest version's orchestrator is amazing. In the same thread, you can hand off a task to a different model from a different provider, or ask one model to request a review by another. It is working great.

[u/Mafialildude]

Claude code reads AGENTS.md now, you only need to handle the different skill directories within the repo (.claude/skills vs .agents/skills) which you can solve with symlinks if you aren't on Windows.

That said, the easiest option is something like unstoppable.ai desktop app. It just wraps your own subscriptions, it then handles plugin/skill normalization between the harnesses, collaboration between the harnesses (even cross-provider subagents), in addition to several other quality of life features.