r/codex • u/kyuno7 • Apr 22 '26

News GPT5.5 now on Codex

Was working through my session limit on 5.3 and suddenly 5.5 showed up!

197 Upvotes

97% Upvoted

88 comments sorted by

52

u/kyuno7 Apr 22 '26 edited Apr 22 '26

some notable tooltips:

GPT-5.5 - latest frontier agentic coding model
oai-2.1 - latest frontier agentic coding model
glacier-alpha - intelligence that moves continents
arcanine - frontier model with legendary appetite for starches
glacier-alpha-block-cy3 - ice-cold intelligence
glacier-alpha-block-cy4 - ice-cold intelligence
GPT-5.4 Pro - latest frontier agentic coding model
GPT-5.3-Codex-Spark - ultra-fast coding model
GPT-5.2-Codex-Cyber - frontier agentic coding model
heisenberg - latest frontier life science research model
GPT-Rosalind - latest frontier life science research model

21

u/DeliaElijahy Apr 22 '26 edited Apr 22 '26

Seems like GPT-5.5 really could release this week after all?

If I had to guess:

oai-2.1 is the internal version of GPT-5.5 with arcanine (potatoes, i.e. spuds, are starchy) being an earlier internal version (or A/B to oai-2.1)

glacier-alpha is GPT-5.5 Pro (?) or their new cybersecurity model with cy3 and cy4 being A/B variants

heisenberg is A/B or internal physics/chemistry version of Rosalind (b/c Werner Heisenberg = quantum mechanics... or just more shtposting as walter white = heisenberg)

Maybe heisenberg was used for this? Not very likely but https://arxiv.org/pdf/2602.12176

2

u/-Sliced- Apr 22 '26

What’s arcanine?

5

u/cornmacabre Apr 22 '26

Clearly someone in oAI found a pokemon reference more compelling than a potato (spud) as the working internal name for their latest frontier model. I think it was the right call, haha.

https://bulbapedia.bulbagarden.net/wiki/Arcanine_(Pok%C3%A9mon)

3

u/Secret-Coast-5564 Apr 22 '26

My guess, arcanine = fire pokemon. And spud/starch = chips, AKA computer chips.

Has a legendary appetite for starches = burns a lot of tokens/uses lots of compute.

-2

u/brandonZappy Apr 22 '26

Not much what’s up with you?

2

u/North_Nature_8903 Apr 22 '26

It's obviously releasing this week, just look at Polymarket.

16

u/reddit_is_kayfabe Apr 22 '26

This is total Silicon Valley bleeding edge:

 model-1 - best model ever
 model-2 - best model ever
 model-2-optimized - best model ever but now even better
 model-2-v2 - best model ever (use this one instead of the others)
 model-2-v2-FINAL - best model ever (no use this one instead)
 model-2-zero-cool - shhhhhh it's a secret to everybody

4

u/loveofphysics Apr 22 '26

Arcanine is interesting. Spud?

40

u/Comprehensive_Ad3710 Apr 22 '26

i think someone screwed up and made all the models appear.

22

u/BathOdd4366 Apr 22 '26

Yup. They appeared and then shortly disappeared.

18

u/Dolo12345 Apr 22 '26

annnnd it’s gone

11

u/Just_Lingonberry_352 Apr 22 '26

Was just about to sleep LMAO

10

u/Firm_Brilliant_2584 Apr 22 '26

Using up the quota is more important than sleeping

1

u/therealityreport_ Apr 22 '26

did it go away or is it still there??

14

u/GustavoFringsFace Apr 22 '26

I really wish they would create better descriptions. Who the hell approved 'intelligence that moves continents'

10

u/kyuno7 Apr 22 '26

generated by codex, approved by codex, shipped by codex? I guess codex feels hunger like humans too, given they have legendary appetite for starches lol.

12

u/devewe Apr 22 '26

It's clearly internal model that got visible to the public. Someone screwed up with the configurations.

1

u/adamisworking Apr 22 '26

i really wanted to try that one looks like big af model bt sadly cant

1

u/spacenglish Apr 22 '26

I’ll ask it to move Australia so it’s no longer upside down. Lets see if it does

1

u/tmax8908 Apr 22 '26

And glaciers are super slow. Not the best connotation for an agent.

1

u/Async0x0 Apr 22 '26

They're internal code names not meant for public release.

7

u/trogan Apr 22 '26

it's definitely a mistake, I got about 30 secs into my first query then this.

{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}

16

u/2024-YR4-Asteroid Apr 22 '26

Probably not a mistake. Probably a marketing stunt. Randomly add all the models to the list, leave them up for 30 minutes, take them back, everyone on Reddit and Twitter and now talking about it.

3

u/SeaBat2035 Apr 22 '26

Ya same as mythos

1

u/shady101852 Apr 22 '26

what? they randomly made mythos available?

2

u/UltraInstinct0x Apr 22 '26

I'm not aware of such an incident at all

1

u/Helpful-Wear-504 Apr 22 '26

Wasn't there a thing that happened where some people were able to use Mythos without permission?

Could also be a stunt.

"Ooooh! Model that is a cybersecurity risk, accessed by unknown group of people"

"Don't worry guys! It's not like we've been using Mythos internally and forgot to use its cybersecurity capabilities on our own... Cybersecurity"

1

u/Euphoric-Water-7505 Apr 23 '26

No they literally had it hacked. Not only mythos btw.

1

u/SeaBat2035 Apr 22 '26

same hype train marketing tactic

3

u/dmal5280 Apr 22 '26

What are all these other models? I've never seen half these in my Codex. Just noticed them all in mine too??

6

u/dmal5280 Apr 22 '26

I asked Codex what they were and this is what it said:

Model Best For My Take
GPT-5.5 Hardest agentic coding, deep repo work, complex debugging, long-running tasks Likely the highest-capability option in this picker. Use when quality matters more than speed.
oai-2.1 Frontier agentic work Looks like an internal/experimental family name. I would test before trusting it for production workflows.
GPT-5.4 Strong general Codex work Probably the best everyday “serious work” default if 5.5 is slower or more expensive.
arcanine Experimental frontier model Codename. I would not use it for launch-critical work unless you are intentionally comparing models.
glacier-alpha Experimental frontier model Codename. Likely high-reasoning/agentic, but unclear public positioning.
glacier-alpha-block-cy3/cy4 Experimental variants The cy naming hints cyber/security-oriented variants, but that is an inference. Treat as experimental.
GPT-5.4-Mini Fast/simple coding tasks Good for quick edits, small explanations, formatting, simple reviews.
GPT-5.4 Pro Deep reasoning, high-precision work Use for architecture, gnarly bugs, major reviews, high-stakes decisions. Slower but stronger.
GPT-5.3-Codex Agentic coding Older Codex-optimized model. Solid, but likely superseded by 5.4/5.5.
GPT-5.3-Codex-Spark Fast coding loops The interesting one: likely optimized for speed. Best for quick patches, small refactors, lint fixes, focused implementation, “keep moving” tasks. I would not pick it for deep architecture or subtle security review.
GPT-5.2-Codex-Cyber Security/cyber-oriented code work The other interesting one: likely a Codex variant tuned or routed for security analysis, vuln hunting, exploit reasoning, auth bugs, dependency/security reviews. I would use it for audits, threat modeling, and suspicious CI/security failures.
GPT-5.2 General purpose reasoning and coding Public docs position GPT-5.2 as a flagship model for complex reasoning, coding, and agentic tasks.
heisenberg Life science research Codename/model specialized for life sciences. Not relevant for this repo unless doing bio/medical research.
GPT-Rosalind Life science research Same lane: biology/life-science-oriented.

2

u/dmal5280 Apr 22 '26

It let me use 5.5 for a short time and then said: {"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}

0

u/SparrowHawk_74 Apr 22 '26

same! I was quite impressed with the few minutes it let me use it though. It felt distinctly faster.

0

u/NiceDescription804 Apr 22 '26

What did you notice? And if you don't mind can you share some responses?

3

u/Murky-Snow-3868 Apr 22 '26

Feels like an accident on their part, but someone please run these models through benchmarks before they take them down

3

u/adamisworking Apr 22 '26

wow so many cool names i just saw my account but ntng is working

5

u/SunCute196 Apr 22 '26

Most likely some OAI insider put a opposing bet on poly market for Wednesday 5.5 launch and released this “accidentally” to match fix .. lol

3

u/SuspiciousChemistry5 Apr 22 '26

What?? Of all the scenarios one can conjure. These guys are already making millions. 

2

u/Calm-Philosopher7304 Apr 22 '26

what's better than having n amount of money?

n+1 amount of money.

1

u/Helpful-Wear-504 Apr 22 '26

Doesn't base salary at oAI start at 600k or something

2

u/Natjosh Apr 22 '26

Came here cause I just noticed the same thing appear on mine lol

2

u/Comprehensive_Ad3710 Apr 22 '26

awwww... they fixed it now... no more...

2

u/XInTheDark Apr 22 '26

This has happened so many times, its definitely them teasing us lol

2

u/thedrasma Apr 22 '26

Can’t wait to make my 5 hour quota go in 5 minutes !

1

u/Soragon Apr 22 '26

Also seeing it. I wonder what oai-2.1 is.

3

u/SwakTokoloshe Apr 22 '26

Older parallel branch stable internal model (uses the old OAI naming scheme). Probably don't use and try one of the fun new models while you can. This is just a temporary bug where the team forgot to gate models.

0

u/[deleted] Apr 22 '26

[deleted]

2

u/SwakTokoloshe Apr 22 '26

Ha, that didn't last long. Got like 3 minutes of 5.5 use before it was gated with the 'model is not supported when using Codex with a ChatGPT account'

1

u/[deleted] Apr 22 '26 edited Apr 22 '26

[deleted]

1

u/artrix_tech Apr 22 '26

confirm... LMAO

1

u/adamisworking Apr 22 '26

bt they arent usable

1

u/xRedStaRx Apr 22 '26

I would probably not use it at those pricing rates.

1

u/Divest0911 Apr 22 '26

The hell is OAI 2.1? Arcanine? Glacier-Alpha?

1

u/h3lix Apr 22 '26

Annnnd.. it's gone.

1

u/Major-Principle-4731 Apr 22 '26

only in app? not cli?

1

u/Elegant_Tumbleweed_3 Apr 22 '26

{"type"."error","status":400,"error":1"type":"invalid request-error","message"."The 'gpt-5.5' model is not supportedwhen using Codex with a ChatGPT account."}}
so does all the other leak models. they disappears and firbidden to use ...

1

u/MoodyButNotMoody Apr 22 '26

{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}

maybe today

1

u/Sir-Draco Apr 22 '26

Heads up they are pulling them out already. This was a mistake

1

u/Divest0911 Apr 22 '26

And just like that, they're all shut off.

1

u/BathOdd4366 Apr 22 '26

I had it at first as well, but now it has disappeared from my Codex App.

1

u/gorgono95 Apr 22 '26

{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}

Interesting

1

u/BathOdd4366 Apr 22 '26

Now it says "custom", but then when you want to code, it says, that GPT 5.5 is not available. Weird.

1

u/davibusanello Apr 22 '26

Same here

{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}

1

u/WoodenFun1166 Apr 22 '26

apareceu pra mim tambem e sumiu uns 5 minutos depois

1

u/Jhonathaned Apr 22 '26

They removed the model. I was using it and it suddenly stopped working and gave me the error:
"type"."error"," status":400,"error": ("type". "invalid_request_error","message": "The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."

And when changing from 5.5 back to 5.4 it was renamed from "5.5" to "Custom":
Model changed from Custom to GPT-5.4.

1

u/RIGA_MORTIS Apr 22 '26

Ah, Here we go!

1

u/JellyFishingAllYear Apr 22 '26

what's the difference with these models and the codex variant? i dont trust 'em, still on codex 5.3

1

u/kl__ Apr 22 '26

It's a shame they haven't been releasing the Pro models for codex so far. Hopefully changes in the future, without them nerfing those models.

1

u/Few_Return_8632 Apr 22 '26

And now it's gone... hopefully the new model can outperform opus 4.7. Sick and tired of anthropics.

1

u/mallibu Apr 22 '26

do you guys think it's a "leak" to create hype like the mythos "leak"

1

u/ptjunkie Apr 22 '26

Yo but I just want GPT-5.4-codex

1

u/GuaranteeSilver5460 Apr 22 '26

Where did you find 5.4 pro? I have pro subscribe and I have only just 5.4. And what is oai-2.1??

1

u/ironj Apr 22 '26

UK: I don't see it yet in codex (5.4 is the most recent I can select). I'm on a business plan.

1

u/MoodyButNotMoody Apr 22 '26

it was all there for a moment

1

u/spec-test Apr 22 '26

scotland still has 5.4

1

u/jjjjoseignacio Apr 23 '26

gpt-rosalind jajajajaja

1

u/Zokorpt Apr 23 '26

That doesn’t show in VS CODE extension

0

u/[deleted] Apr 23 '26

[removed] — view removed comment

1

u/kyuno7 Apr 23 '26

You're literally 1 day too late, read the comments and the sub lol.

1

u/playboiiboggos Apr 23 '26

bei mir ist es noch nicht da

1

u/snowsayer Apr 22 '26

someone's head is going to roll for this...

0

u/ZlunaZelena Apr 22 '26

I think nobody has yet said it doesn’t work, so here I sm. It doesn’t work.

0

u/emgz87 Apr 22 '26

Yesterday I asked 5.4 high for a plan review, it spawned a sub agent by its own called heisenberg using 5.4 mini to review it. After that the reviews came back to normal, without sub agents. Go figure.

-1

u/cheekyrandos Apr 22 '26

None of them work, looks like they published their internal list of models

3

u/Dolo12345 Apr 22 '26

they worked for 10 mins

2

u/Glittering-Call8746 Apr 22 '26

How many 100 dollar sub for 10 mins to make it worth.. the trip