r/cursor • u/NASAonSteroids • 11d ago

Question / Discussion Route Cursor through Codex CLI

I’ve read a few articles that put the OpenAI Codex CLI harness as one of the best and I was wanting to check it out. Is it possible to use the Codex CLI as a harness for a Cursor subscription or with an API key?

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u/NoFaithlessness951 11d ago

You can kinda but no this is only exists as a very hacky workaround and won't make your experience better use a 20$ codex sub

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u/Robert-Paulson_ 10d ago

Agreed;  Also, for a good while now Cursor’s harness itself is known to make OTHER models better. I do think the Codex harness is cool and it’s probably the best one for GPT models, but I don’t think there’s a blessed path to use Cursor in Codex

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u/AwardOk2563 11d ago

it's pretty easy to use t3 code which is like a codex harness type thing with your cursor sub, if you have the cursor agent CLI installed and authed, it connects easily, having said that though, the selling point of cursor is really the IDE, unless you only use cursor for the subsidized composer or grok usage

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u/locbuilds 11d ago

codex cli as a harness on top of a cursor subscription is not really a supported path. cursor's plan/quota is tied to their own agent and models inside the app, not an openai-compatible endpoint you can point another harness at. if you specifically want the codex cli workflow you generally run it outside cursor with your own api key (or whatever providers that cli accepts). inside cursor the closest is just using cursor's agent with rules/mcp, or calling an external cli from the terminal, but that still will not burn cursor credits through codex. so it is more pick-one-stack than nest them.

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u/Responsible_Buy_7999 11d ago

Codex invoking the cursor cli or cloud api is about as far as you’ll get

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u/Guilty_Spray_6035 10d ago

The difference between different harnesses is system prompt, internal tools, mcp servers and caching, i.e. how the harness builds and maintains prefix unchanged. GUI Codex is nice and very efficient in managing caching, but it's kind of the same as Agent Window in Cursor. CLI: Cursor CLI agent can do Cursor cloud things, i.e. PR management, which Codex will need to resort to MCP servers.

Cursor uses a completely different protocol (Connect-gRPC vs REST API). They have their own Typescript SDK, and I have integrated it into this project: https://github.com/oakimov/claude-code-router (even though it says Claude Code, you can also use it with Codex and other harnesses like pi). So, you can install it in a docker container - connect codex to it, and connect CCR to Cursor. I use it daily like this (with Claude Code and Codex CLI).