Google adds Gemini 4 Argon to AI Mode for Pro and Ultra users

Google AI Pro and Ultra subscribers in Australia and more than 120 other countries and territories can now switch AI Mode to Gemini 4 Argon, Google's newest model. Google Search's VP of Product, Robby Stein, posted the news on X on 13 October, the same day the model reached developers, enterprise customers and the Gemini app.

Free users of AI Mode are not affected. They keep the default model, and Google has said nothing about changing that.

Argon joins the subscriber menu

Subscribers pick Argon from the "+" icon in the "Ask anything" bar in AI Mode. It is the same menu Google used to add Gemini 3.7 Flash on 14 August and 3.8 Flash on 2 September.

Stein said Argon "brings big improvements to tackling nuanced, multi-step tasks in AI Mode" and copes better with follow-up instructions as a conversation goes on. Google's launch post for the model makes a similar claim, saying it follows style instructions better than any earlier Gemini model.

Because the rollout is staged, not every subscriber will see the option straight away. At least one Pro subscriber reported that the option had not appeared by midday US time on launch day. Google's help page lists Australia, but no Google page names a language, and the 3.7 Flash rollout was English only, so Australian subscribers should check rather than assume.

From cyber defenders to paying subscribers in two weeks

Google introduced Argon on 30 September as a frontier model aimed at coding, enterprise knowledge work such as legal and finance, and cyber security defence. The first release went to a set of trusted cyber defenders through Google's Fairwind Program, with a promise that paid API customers and Google AI Ultra subscribers would come next.

That first announcement did not mention Pro subscribers at all. The 13 October post lists them alongside Ultra, which means the lower-priced Pro tier, not just Ultra, now gets the model inside Search. Developers get it through the paid tier of the Gemini API, and Ultra subscribers can also use it in Antigravity, Google's coding tool.

Google's 30 September post framed the release as deliberately phased. It said it was taking part in the US government's voluntary process for pre-release model access and was using feedback from early testers to adjust the model's guardrails before opening it to developers, enterprises and consumers. The 13 October launch also began extending the Fairwind Program to hundreds of additional partners.

Why AI Mode has mostly run on Flash models

Since Gemini 3 Pro arrived as an AI Mode option in November, the additions to the menu have mostly come from the Flash line. December brought Gemini 3 Flash as the default, Google I/O in May made 3.5 Flash the default worldwide, and subscribers gained 3.7 Flash in August and 3.8 Flash in September.

Google has pointed to cost and speed. Flash models answer faster and cost less to run, which matters when it has to run at the scale of Google Search. Argon is the first model in the Gemini 4 family to reach AI Mode, and it arrives as an option rather than the default.

Whether it stays an option is not settled. Past launches went both ways: Gemini 3 Flash and 3.5 Flash were the default from day one, whereas Gemini 3 Pro has only ever been an option, and neither Google post says which path Argon will take. The launch post also refers to "the rest of the Gemini 4 family" without saying which of those models will appear in Search, or whether the Flash options stay in the menu once the rollout finishes.

Google has not said what Argon costs to run inside Search, but the API price gives a sense of scale: an introductory US$2 per million input tokens and US$10 per million output tokens, with cached input discounted by 95 per cent. Google has also raised the model's token limit in the Gemini API to 1 million, up from a previous 64K output limit, which is headroom for long, multi-step work rather than a quick search answer.

Google's help page lagged at first: on 13 October it still offered just two settings, "Pro" and "Fast", with Pro identified as Gemini 3 Pro. It has since added an Argon section listing 122 countries and territories, Australia included, an 18-plus age limit, personal accounts only and daily usage limits.

Links lapsed in 3.8 Flash for about a day

At least one early screenshot from a subscriber who already has Argon shows links inside the AI Mode response. That matters because of what happened last time. For about a day after 3.8 Flash reached AI Mode on 2 September, its answers showed few or no links, until Google's Robby Stein said it "isn't working as intended" and a fix followed the next morning. Google's own documentation describes AI Mode answers as including links to supporting websites, so links are the intended behaviour.

The open question for Argon is which pages it chooses to link to. An AI answer without links sends nobody to a website, while one with links gives a named business at least a chance of a click. Google has not published anything about how Argon picks its sources in AI Mode, and that could shift as the rollout continues.

Watch subscribers' multi-step provider comparisons

Most people who search for a plumber, an accountant or a cafe are not paying for Google AI Pro, so the AI Mode answer they see today is still produced by the default Flash model. The change affects a smaller group, but it is the group most likely to use AI Mode for involved, multi-step research, such as comparing several providers before making a shortlist.

Those are the conversations in which a business either gets named or gets left out, so the model handling them is relevant even if few customers use it. A model that handles follow-up questions better may also change which businesses survive to the end of a long conversation.

Google also describes a change in how Argon writes. It says the model answers more directly with less hedging, repeats itself less, skips clichés and, on longer tasks, reports its progress more often. If that carries into AI Mode, answers may get shorter and more decisive, which makes the difference between being named and being left out sharper.

Google adds that Argon is its most resilient model yet against indirect prompt injection, where instructions hidden in the content a model reads try to steer its output. For a model that reads web pages, that suggests hidden text written to steer AI answers is even less likely to work than before.

The bigger worry for site owners, that open web content has become free training data for AI answers that send little traffic back, does not go away with a model change. A model that shows links does at least make the effect measurable.

Run your customers' questions through Argon and 3.8 Flash

If anyone in your business has a Google AI Pro or Ultra subscription, open AI Mode and look for Argon under the "+" icon. If it is not there yet, check again in a few days.

Once it appears, run the questions your customers actually ask, as a conversation rather than a single query. Start broad ("who installs ducted heating in Geelong"), then narrow with follow-ups about price, timing and reviews. If 3.8 Flash is still listed, run the same sequence on both models and record which businesses each one names and which pages it links.

Three things to note from that test:

• Whether your business is named at all, and at which step of the conversation it drops out.
• Which of your pages are linked, if any. If the answer draws on a competitor's page for a question you also answer, compare the two pages.
• Whether the information Google gives about you is current. If it quotes an old price or a closed location, fix the source page.

If the answer to a service question on your site lives inside a brochure, it is worth revisiting Google's recent explanation of how Search handles PDF files, where Google's Martin Splitt and John Mueller recommended HTML as the default, keeping PDFs for documents that need a fixed print layout. The same logic applies to anything an AI model needs to read and cite.

Watch Search Console over the following weeks. AI Mode clicks are still counted inside the normal Web search totals, but since 31 August every site has a Generative AI performance report showing impressions from AI Overviews and AI Mode. It combines the two and shows no clicks, and with the recent Search Console data delays, avoid reading too much into a short window. A subscriber-only model will not move the numbers for most sites, but it tells you which direction the default is likely to head when the next Gemini 4 model arrives.