Gemini 4 Argon lands on Google AI Ultra, not Antigravity's lower tiers

The rollout was staged rather than simultaneous. Google announced Gemini 4 Argon on September 30, 2026, giving first access to cyber-defense specialists, and only opened it generally on October 13. That two-week gap explains why plan and surface details were still being sorted out when the public release landed.

The plan table is the source of the confusion. Antigravity lists Argon only for Google AI Ultra, and a check of the Antigravity CLI on October 14 showed no Argon entry on a non-Ultra plan, consistent with that table. Meanwhile the Gemini app and Search's AI Mode include Pro, so the same model is reachable on different tiers depending on where you look. Google's developer post frames API access around the paid tier without mentioning free usage.

Pricing carries a deadline that matters more than the spec debate. The introductory rates of $2 per million input tokens and $10 per million output tokens run only through November 30, 2026, then double to $4 and $20. The "1 million tokens" claim is described in Google's English announcement as an output limit raised from 64K, while a Japanese post refers to a combined input-output limit; an input-only cap was not found in official materials. Google's own benchmark figures, such as 77.9% on DeepSWE v1.1 and 51.3% on AutomationBench, are company-reported.