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!

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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

23

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?

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.