Google added Gemini 4 Argon to the AI Mode model menu for Google AI Pro and Ultra subscribers, on the same day the model became available to developers, enterprises, and Gemini app users. Robby Stein, VP of Product for Google Search, announced the rollout on X, saying Argon "is now rolling out globally in Search" and that subscribers can switch to it using the "+" icon.

Thirteen days ago, Google's first Argon announcement did not mention Pro subscribers at all. Today's launch post lists them alongside Ultra subscribers. Nothing announced today changes the default for free-tier AI Mode users.

What does the rollout change for subscribers?

Subscribers can pick Argon from the "+" icon in AI Mode's "Ask anything" bar. It is the same menu that added 3.7 Flash in August and 3.8 Flash in September.

Stein says Argon "brings big improvements to tackling nuanced, multi-step tasks in AI Mode" and is "better at understanding your intent and following your instructions in back and forth conversations." The launch post makes a parallel claim for the model as a whole, saying it "follows style instructions better than any of our previous Gemini models."

Neither post states a supported language. The 3.7 Flash rollout, for comparison, was English only.

Because the rollout is gradual, Argon may not appear for every subscriber yet. Search Engine Journal reporter Matt Southern reported that as of 12:17 p.m. ET, Argon had not appeared in the menu on his own Pro account.

From the Fairwind Program to paying subscribers

Google introduced Argon on Sept. 30 as a frontier model for coding, enterprise knowledge work, and cyber defense, and released it to "a set of trusted cyber defenders" through its Fairwind Program. That first post said the wider release would come "as soon as possible" and would start "with paid API customers and Google AI Ultra subscribers."

Today's post collapses the sequence into a single launch:

• Developers access Argon through the Gemini API's paid tier
• Ultra subscribers can use it in Google Antigravity, Google's coding tool
• Pro and Ultra subscribers can find it in the Gemini app and in AI Mode

A break in the Flash pattern

Gemini 3 Pro became available as an option in AI Mode in November. Every addition to the menu since then has been a Flash model. Gemini 3 Flash became the default in December. Gemini 3.5 Flash took over as the global default at I/O in May. Gemini 3.7 Flash joined the menu on Aug. 14, and 3.8 Flash followed on Sept. 2.

In February, Google explained its reasoning for running AI Mode on Flash models: they cost less and respond faster, which lets them run at Search scale.

Google's support page for AI Mode's model menu, read today, still names only "Pro" and "Fast" as options and describes the Pro option as Gemini 3 Pro. It read the same way on Aug. 14 and Sept. 2. The documentation lags the product.

Why this matters for marketers

Argon is available by subscription only, just like the two Flash models that joined the menu before it. Free-tier users, the bulk of Search traffic, will not see it.

The improvements Google describes concern multi-step tasks and back-and-forth conversations. A multi-step query with follow-up questions is therefore the honest test. Once Argon appears in the menu, and if 3.8 Flash is still listed alongside it, run the same sequence through both models and note which one answers each time.

Will Argon become the default?

Neither Google's launch post nor Stein's X post says. Precedent cuts both ways. Gemini 3 Flash and 3.5 Flash both launched as the default, while Gemini 3 Pro launched as an option and has remained one.

The launch post closes by saying Google looks forward to "bringing you the rest of the Gemini 4 family," without specifying which of those models will reach AI Mode. For teams optimizing content for AI-driven search, the subscriber-only tier matters less today than the signal it sends: Google is testing frontier models inside Search, and defaults can follow.

By Priya Raman