Antigravity Pro Users Lost Gemini 3.1 Pro, and Didn't Get Gemini 4 Argon
TL;DR: On October 13, 2026, Google removed Gemini 3.1 Pro from Antigravity. Hours later it launched Gemini 4 Argon, but in Antigravity only Google AI Ultra subscribers can use it. On a Google AI Pro account, Argon shows up in the model picker greyed out as "Unavailable": "Gemini 4 Argon is currently available to Ultra plan subscribers." So for Pro (and free) users, the strongest Gemini left in Antigravity is Gemini 3.8 Flash. Pro subscribers can use Argon in the Gemini app instead.
Update (Oct 16, 2026): Google has since opened Gemini 4 Argon to Pro. Since 23:03 UTC on October 15, our Pro account shows Gemini 4 Argon (Low / Medium / High) tagged "New" instead of "Unavailable". The official models page now lists Argon for Pro (non-trial subscriptions only), Ultra and Enterprise, but not for the Antigravity IDE. Gemini 3.1 Pro, 3.6 Flash and 3.7 Flash remain Enterprise-only.
What happened, hour by hour
We track the model list Antigravity receives from Google's servers every hour, on a Google AI Pro account and on a free account. Times are UTC.
| When (UTC) | What changed |
|---|---|
| Oct 12 | Gemini 3.1 Pro, 3.7 Flash and 3.6 Flash get a "Leaving Soon" tag. 3.1 Pro's tooltip: "Use Gemini 3.8 Flash! As a newer model, it delivers more intelligence at 2x the speed for 70% less cost than Gemini 3.1 Pro." |
| Oct 12, ~22:00 | All of them disappear from the picker and from agy models in the CLI. Gemini 3.8 Flash is now the only Gemini model left. |
| Oct 13 | Google launches Gemini 4 Argon. For Antigravity, the announcement says Ultra subscribers only. |
| Oct 13, 16:03 | On our Pro account, "Gemini 4 Argon (Medium)" appears at the top of the picker, disabled and tagged "Unavailable". |
| Oct 13, 20:03 | That entry is replaced by a single "Gemini 4 Argon", still "Unavailable", now at the bottom of the list. |
This is the model list our Pro account receives now:
The free plan gets the same greyed-out Argon entry. The notices on the Claude models there say that third-party models leave the free plan on November 2:
Who gets Gemini 4 Argon where
| Free | Google AI Pro | Google AI Ultra | |
|---|---|---|---|
| Gemini app and AI Mode in Search | no | yes | yes |
| Canvas in the Gemini app (code generation) | no | yes | yes |
| Google Antigravity | no ("Unavailable") | no ("Unavailable") | yes |
| Google AI Studio | no | no | yes |
| Gemini API | paid tier only |
Based on Google's announcement and launch coverage (sources below). The rollout in the Gemini app is gradual, so some Pro accounts may not see Argon there yet.
Why this stings for Pro users
Until October 12, a Pro subscriber in Antigravity could pick Gemini 3.1 Pro for long agentic coding tasks. Today, the Gemini part of the picker on a Pro account has only:
- Gemini 3.8 Flash (Low / Medium / High). Google pitches it as smarter, faster and cheaper than 3.1 Pro, but it is still a Flash model.
- Gemini 4 Argon, which you can see but not select.
The other options on Pro are Claude Opus 5.5 and Claude Sonnet 5.5 (tagged "New") and GPT-OSS 120B, which is leaving on November 2. Those models draw from a separate usage pool from Gemini.
So Pro subscribers lost the Pro-class Gemini in Antigravity and didn't get the new flagship. If Argon is what you need for coding, the options are:
- upgrade to Ultra;
- use Argon in the Gemini app (Canvas) on Pro and bring the code back by hand;
- use the paid Gemini API with your own key.
We saw it coming
On October 12 we found the model IDs gemini-4-argon, -low, -medium and -high, plus ready-made picker labels, inside Antigravity desktop app 2.23.0, a day before the launch. The labels and variants were already in the client. Turning Argon on was purely a server-side switch, and the "Ultra only" rule turned out to be a server-side switch too.
One detail hints at how Google wired it. The entry Pro accounts saw first used internal slot M418, the one that replaced it uses M421. That leaves room for three real Argon variants (Low / Medium / High) for Ultra plus a separate "Unavailable" placeholder for everyone else. We can't confirm this without an Ultra account.
FAQ
Can Google AI Pro subscribers use Gemini 4 Argon in Antigravity? No, as of October 13, 2026. The model picker shows it as "Unavailable" with the note that it is available to Ultra plan subscribers.
Where can Pro subscribers use Gemini 4 Argon? In the Gemini app (including Canvas for code) and in AI Mode in Search, according to Google's announcement. The rollout is gradual.
Is Gemini 3.1 Pro still available in Antigravity? No. It was tagged "Leaving Soon" on October 12 and removed from both the app's picker and the CLI by the end of that day (UTC).
What is the best Gemini model in Antigravity on the Pro plan now? Gemini 3.8 Flash (High).
Does the free plan get Argon? No. Free accounts see the same "Unavailable" entry.
Sources
- Our hourly captures of the Antigravity model list on a Google AI Pro account and a free account, October 12–13, 2026
- Gemini 4 Argon is now available in the Gemini app (Google blog)
- Sundar Pichai's announcement on X
- Android Police: Gemini 4 Argon is here
- OfficeChai: Argon for Pro and Ultra in the Gemini app, Ultra in Antigravity
- Our earlier report: Gemini 4 Argon labels found in Antigravity 2.23.0 (
gemini-4-argon-antigravity)