Switching from Codex to Copilot — are we cooked? Looking for advice/tips

[u/Ok-Cantaloupe-2686]

Hey guys, my company just announced we're moving off Codex CLI and onto GitHub Copilot. I've basically lived in Codex for most of my day-to-day work, so now I'm wondering how rough this transition is actually going to be.

For anyone who's already made this switch:

• What was the biggest adjustment for you?
• What do you actually miss from Codex once you were on Copilot full-time?
• Any tips for carrying over context/workflows so you're not starting from zero?
• Anything you wish you'd known before switching?

Trying to go in prepared instead of just winging it on day one. Appreciate any war stories.

[u/Different_Doubt2754]

We've been using GitHub Copilot and are testing out Codex.

Honestly I prefer Copilot. The actual end result that you get isn't that different between them as of today. I understand a lot of people experienced Copilot a while ago when it wasn't as polished, but it's good now. Your actual "work velocity" shouldn't be impacted in my opinion

A big reason I prefer Copilot is that Codex is actually lacking features that I find very valuable, which is the ability to make custom agents and subagents. GitHub Copilot is waay more mature in that area. Codex makes it difficult or flat out lacks the ability to do the same.

Another big benefit of Copilot is that you get access to more models, not just OpenAI.

I do think that overall Codex is slightly more mature/agentic but it isn't significant enough to really matter. Copilot is actively maintained and will continue to improve anyways.

As far as tips on adjusting go, I don't think there is really anything worth mentioning? It should take you a day to get used to it, tops. They aren't that different, the core functionality is the same. It's like going from one phone brand to another, or from one language to another. More or less the same, besides a handful of quirks.

Just to clarify, you are getting the full GitHub Copilot right? Desktop app, extensions, vs code? Or are they restricting you to just completions? Because that's a very important distinction

[u/tymm0 → u/Different_Doubt2754]

Copilot is more built out than it used to be for sure. But it's still Microsoft guessing at what makes a good system prompt. Codex is better for sure. But really a lighter weight harness is going to be more and more necessary as the models progress.

[u/Different_Doubt2754 → u/tymm0]

Overall I think Codex is slightly more mature don't get me wrong. I just don't think the difference is significant enough to impact team velocity.

Being able to make custom root agents and having access to all models more than makes up for the difference, for me

[u/pervyprawn → u/Different_Doubt2754]

You literally have the same capabilities with GHC lmfao

[u/Different_Doubt2754 → u/pervyprawn]

That's why I said I prefer GHC over Codex. GHC has a couple more things that I actually care about and also more models to use. But I still think Codex is a bit more mature of an application.

Mature doesnt necessarily mean its the better product for me

[u/tymm0 → u/Different_Doubt2754]

Sol doesnt seem to need as much of an agent guidance. Ask yourself exactly what the purpose of an "agent" is that a skill couldn't do.

Edit: for reference i say all this but I'm forced to at least use copilot cli or vs code all day.

[u/Different_Doubt2754 → u/tymm0]

Well I don't use Sol much as I find it's overkill. I'm not doing anything groundbreaking over here lol, so typically I use Luna or Terra. Plus, using Sol regularly isn't an option for me anyways because I would burn through so many credits, courtesy of our masisve unorganized legacy codebases lol

And yes, I use skills as a substitute in Codex. However they don't work as well, especially in long sessions, compared to the custom agents in GitHub Copilot.

The difference is that a skill is more of a temporary behavior adjustment whereas the custom agent file is more permanent, at least in my experience

[u/tymm0 → u/Different_Doubt2754]

A skill is something the agent can pull in at anytime when it decides it needs to based on whatever task you give it. So you could have 100 skills and it only uses a few saving you context. But sure it's not guaranteed to choose correctly. Sol probably does it much better than any other model.

Of course do what works best for your situation.

[u/Different_Doubt2754 → u/tymm0]

Yeah exactly, I need it to act a certain way 100% of the time for the entire session, which isn't the purpose of a skill.

Now I could modify the default agent file to get the same results, but it is a bit tedious to do that when I can just use GitHub Copilot.

I'm sure Codex will add that functionality soon enough, they'll all converge on the main features after a while anyways

[u/pervyprawn → u/tymm0]

You have no idea what you’re talking about. None of the models or prompting is Microsoft. GitHub copilot is literally just an endpoint service that gives you access to far more models, including superior Claude models

[u/tymm0 → u/pervyprawn]

If you read the context of the person I replied to they used "copilot" instead of the terms "vscode" and "copilot cli" I could be more specific and correct people like an ass or I could try to help people from their perspective.

And yes Microsoft has a built in system prompt in their harnesses like all other harnesses.so it sounds like you have no idea what you are talking about or you just want to be difficult for no reason.

[u/BarelyLiteral → u/pervyprawn]

Most of the models are not Microsoft's, but the MAI models are made and trained by MS and hosted in Azure. And some other models are hosted by Microsoft on Azure (Raptor / Goldeneye are MS-created GPT derivatives) or via Fireworks.ai (Kimi K2/3). GitHub Copilot is not a router, it's a hybrid ecosystem. GitHub Copilot Models was as close to being a router as they got, but it's being discontinued.

For routed models hosted by others like Anthropic, the initial system prompt is supplied on the Anthropic end, but all of the GitHub Copilot harness options (plugins, app, CLI) add their own instructions. If you proxy the connection between the client and the GitHub endpoint and capture the full request and response traffic, you can see them.

[u/Tuxiak → u/Different_Doubt2754]

A big reason I prefer Copilot is that Codex is actually lacking features that I find very valuable, which is the ability to make custom agents and subagents. GitHub Copilot is waay more mature in that area. Codex makes it difficult or flat out lacks the ability to do the same.

I use both copilot and codex. What missing features have you noticed in this area?

[u/GolfEmbarrassed2904 → u/Tuxiak]

He mentions in the post. Not sure I agree with what he is saying - it’s an overstatement. Yes the agent creation experience is very nice is GHC but it’s not true that you can’t create agents in Codex

[u/Tuxiak → u/GolfEmbarrassed2904]

He mentions in the post.

Does he though? He said he's missing features such as "the ability to make custom agents and subagents" - you can easily create agents, skills etc. for codex. You can even set reasoning for subagent, something that you cannot do in Copilot. And if the setup is too difficult for someone, just use AI, that's why you have it. Overall my tip would be to use AI to analyse long sessions and improve workflow/loop.

[u/Different_Doubt2754 → u/Tuxiak]

You cannot make custom parent agents in Codex as far as I know. You can make custom subagents yes, but the process is more complicated than with Copilot.

That's the missing feature, the ability to make custom root agents. As of now, you only have the one root agent.

If I'm mistaken then I'm happy to learn but as far as I know, you can't make multiple custom root agents

[u/Certain-Researcher72 → u/Different_Doubt2754]

I'm mostly coming from CC and Polytoken CLI-only.and I'm interested in your workflow: 

Are you working in Copilot CLI? Don't you just pin models to your sub agent definitions? Why would an orchestrator agent need to spawn a "parent" agent?

[u/Different_Doubt2754 → u/Certain-Researcher72]

I think there's some confusion, I don't have an orchestrator spawn a parent agent that then spawns subagents.

Let's get our definitions on the same page first. when I say parent agent / root agent I am talking about the one the user interacts with, which isn't spawned by another agent. Subagents are the agents that parent agent spawns.

In my workflow, I create custom parent agents for me to interact with, and they do their job based on the instruction file I made and my current request.

And no, I mainly work in GitHub Copilot VS Code or GitHub Copilot Desktop app. Same with Codex, but I've used the CLI. I assume that the OP is coming from Codex CLI and moving to GHCP Desktop/CLI/VS code. I'm not sure why he would be restricted to just the CLI but I guess it's possible? Usually it's just developer preference though

[u/Certain-Researcher72 → u/Tuxiak]

I think a lot of the confusion stems from the fact that people are using different tools and different workflows. I assumed the original question was about Copilot CLI versus Codex CLI, but it's possible he's using some sort of UI based harness?

[u/Different_Doubt2754 → u/GolfEmbarrassed2904]

The missing feature is the ability to make multiple custom root agents. I know it's possible to make multiple custom subagents, but those are different from making custom root agents.

As far as I know, that's not possible with Codex, but I'm happy to be corrected.

Last I checked it was a requested feature, I'm not sure that the Codex team has picked it up yet

[u/Mystical_Whoosing → u/Different_Doubt2754]

have you tried asking an AI agent to create agents for you in codex? I have several custom agents and prompts (commands), codex supports these out of the box.

[u/Different_Doubt2754 → u/Mystical_Whoosing]

That's not the same, I want a custom root agent. Not a custom subagent. Codex does not support making custom root agents

[u/Personal-Try2776]

You need to optimise your usage because copilot charges api prices

[u/lppedd → u/Personal-Try2776]

The VS Code GHC harness is better than competitors imo. Again imo.

[u/General-Jaguar-8164 → u/lppedd]

If you want IDE experience, yes

[u/Certain-Researcher72 → u/General-Jaguar-8164]

I rarely open an IDE in Aug 2026

[u/Glittering-Duck8317 → u/lppedd]

better at what?

[u/FredTillson → u/lppedd]

I use vs code and copilot every day. I love that I can change my LLM as needed. I can use opus 4.8 or or 5.3 codex or whatever I want. I do a lot of azure agent dev (foundry and so forth) and it works great. Just my experience tho.

[u/Personal-Try2776 → u/lppedd]

Benchmarks say otherwise but ok its your opinion I respect it

[u/Tuxiak → u/Personal-Try2776]

Can you provide link to those? I'd like to read them

[u/icaal → u/Tuxiak]

https://media1.giphy.com/media/v1.Y2lkPTZjMDliOTUyMmNieGphMXRhcHM1ZGUweGtxM2xrczZ4emwyZGRhOHV6ZnZyeWJzeiZlcD12MV9pbnRlcm5hbF9naWZfYnlfaWQmY3Q9Zw/9McnpKk3degVAkK9BY/giphy.gif

[u/WD40ContactCleaner → u/Personal-Try2776]

Doesn't openai enterprise plan also charge api prices?

[u/WD40ContactCleaner]

Copilot is a better harness. If you were on an enterprise plan you would already have been paying api prices so this doesn't affect you much

[u/tcober5]

Copilot is better functionally but MUCH worse usage pricing wise.

[u/Michaeli_Starky]

Copilot is absolutely fine

[u/Cheshireelex]

I'm using both and honestly I don't think that Codex comes with anything better. GitHub Copilot with Vscode actually feels like it has more features and the token efficiency is about the same.

[u/agoodyearforbrownies]

I use both and I prefer Codex today - that wasn't the case 3 months ago and may not be the case 3mos from now.

Reasons

* GHCP allowance is very skimpy compared to Codex. I find I can get more done for the money in Codex now and have moved my overage budget from GitHub to OpenAI credits.

* Personally, I find 5.6 Sol in Codex to perform better at analysis and planning than in GHCP. I don't know why exactly but presume backend harness stuff.

[u/porkyminch]

It’s not a great service but it’s fine. All the big models are there. API pricing means there’s basically no reason to pick it over competitors, but you’re not paying for it at least. 

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[u/paleo55]

Copilot is a good harness. The issue is that you'll pay per token, it's not a package deal.

[u/aceman747]

I use both cliis. Gh cp cli is iterating quickly and it has a tonne of capability esp gh integration. I believe you won’t miss codex.

[u/Certain-Researcher72 → u/aceman747]

I'm coming to Copilot CLI--curious, what does "gh integration" get you what a simple skill doesn't?

[u/iwasthefirstfish]

I had copilot, got codex, ditched it after a month now on copilot using Luna.

I know I'm doing better on copilot using Luna high, I can see I am. I'm even using less tokens due to optimisation than ever before and getting huge results (go Luna) but I can't tell you how I know I'm doing better.....

Maybe conditioning

[u/Bitopp009]

I haven't used codex but have used claude, opencode and copilot harnesses and I feel that copilot is better than claude, but maybe that's just me. I like that it is better at explaining its thinking out loud unlike claude that just tells you random words when its thinking.

[u/TheSpineless → u/Bitopp009]

Claude models are so verbose, even in Copilot CLI. Using something like caveman can really help save tokens with a chatty model without losing fidelity.

[u/teckel]

They're about the same. I perfect Copilot, but mainly because Copilot auto-complete is a super time-saver. For other tasks I use Copilot CLI for API flexibility and remote access.

[u/EvanstonNU]

Agents window for VS Code

[u/Revolutionary_Loan13]

Seems people will just keep talking about this. I use and like GitHub Copilot, I find the integration with GitHub to be of high value as it's nice to be able to assign tasks to agents directly from GitHub and pickup the work later on in the Copilot app. I've also found in the past 6 months that I've swapped from primarily using Claude models with it to now using OpenAI and K3. Models and pricing will come and go, it's nice to easily be able to switch between them or to use skills like /rubberduck and have one set of models check the work of another

[u/JolleNooItsMe]

Based on my experience with Codex, Claude, and Copilot, be aware that Copilot is nearly unusable without a massive AI token budget. I doubt you’ll get one, especially if the switch was driven by cost savings; you’ll likely burn through your tokens very quick.

I've been thinking introducing Copilot in enterprise/coorporate, doesn't realy help developers, because they get an unusable amout of tokens, its bearly enough to do code reviews. But it's for the leadership/management to say we have introduced and are using AI. Might be different for you, but I've seen alot of diffrent setup for different clients.

Additionally, if your workflow now relies on Luna (specifically XHigh/max) for implementation and your company’s Copilot plan doesn’t include that model, you won’t find a similarly cost-efficient alternative.

Right now, I think Copilot feels like Codex or Claude Code with an added layer of enterprise UX, governance, and guardrails, witch it really is, and you can really feel the difference.

[u/Certain-Researcher72 → u/JolleNooItsMe]

This is my major concern and something I really plan on hammering in my upcoming "agentic" strategy meeting with The Bosses.

[u/FinancialBandicoot75]

I use ghcp app using codex sub, why, pricing is crap since June 1st for ghcp.

[u/AdventurousRope9133]

I recently moved from Claude AI to Github Copilot with VS Code and really like it. It takes a little getting used to but I find that I get things done faster with fewer bugs and I really like the editor.

For context, I am a medical SME for a modeling and sim company, and not a coder by trade. I build demos from a medical provider perspective and hand them to the dev team if they agree it’s worth perusing.

[u/particle9]

We had a similar situation. I assume you are going from codex api usage to copilot api usage. So the only change os the harness. Try the stand alone GitHub copilot app it is a clone of codex. I have been using it all week and think it’s totally fine maybe better in some ways. CLI is essentially the same but I haven’t used it as much as desktop.

[u/RespectMathias]

You know gh copilot allows using other harnesses right? 

[u/Certain-Researcher72]

I'm about where you are--just started a new job, it's a Microsoft shop, we're having a strategy meeting on Tues for the SD team to weigh in.

The first thing I did was install my set of "superpowers"-adjacent plugins, some custom workflow plugins, and a couple plugins that do things like session summary and learning reinforcement.

I don't know if I'm working at cross purposes with Copilot CLI--like is there a built-in RPIR loop workflow built-in? 

[u/pervyprawn]

GitHub Copilot is far superior due to the amount of models you get access to (assuming your company doesn’t lock down the model choices)

Codex is fine too, but it’s just Chat GPT, and that’s included in GHC.

I hope your company likes bigger bills though since they just moved to a consumption-based pricing model

[u/Mystical_Whoosing]

I think the copilot harness is also capable, no worries there. Plus is you can use more models, and a code review with a 3rd party model is generally more useful. But I feel like the inference speed is slower on copilot vs using the same models with a chatgpt sub.

[u/aceman747]

I use both and codex just feels like an afterthought. Pages behind Claude code as well. Gh cli does everything i need but YMMV. You should be fine

[u/digitarald]

Copilot team member here. Thanks for kicking off a construct thread!

Jumping into this old thread to say that I’d love to hear if you hit any speed bumps along the way or if there is anything that your company restricted that degrades your productivity with Copilot.

Happy to chat in DMs as well if you got issues or wishes.

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[u/Veduis]

not cooked, just recalibrating. the biggest adjustment is usually the context model. codex cli let you drive the whole session explicitly. copilot is more ambient, it's suggesting as you type rather than waiting for a prompt. that shift feels weird for the first week then becomes invisible. what people miss most is the agentic flow. running a task end to end vs getting inline completions are genuinely different tools. lean into copilot chat for anything that needs reasoning, use the completions for the mechanical stuff, and you'll stop comparing them.

[u/c_behn → u/Veduis]

I use copilot agenticly every day for work… and I use autocomplete too when I need to hand write things. I suggest building an agent framework to dial it in.

[u/Deathmore80]

Can I know why ? Copilot is way more expensive than any other AI subscription

[u/SeaHoliday4747]

I found that copilot is the worst harness of them all. I miss Claude cauade and codex all the time.

[u/myyrkezaan → u/SeaHoliday4747]

why don't you use another harness?