Gemini 4 Argon hints emerge as Google tests Carbon checkpoint

Google appears to be getting closer to the public release of Gemini 4 Argon. Recent Antigravity changes introduce references to the model in its selector alongside three context configurations: 256K by default, 512K consuming approximately 1.3x quota per turn, and 900K consuming around 1.8x quota per turn. These configurations resemble existing options for Gemini Flash models, although the exact relationship between context size and reasoning effort remains unclear.

Meanwhile, Gemini Web now supports low, medium, and high thinking effort settings across available models. This change could help prepare the platform for Gemini 4. Google officially announced Argon on September 30, initially granting access to selected cybersecurity partners, with paid API customers and Google AI Ultra subscribers expected to follow.

Business Insider has also revealed that Google employees are internally testing additional Gemini 4 checkpoints. According to early employee feedback, one of them, Carbon, reportedly feels comparable to Claude Opus 5.5 for coding. The report identifies Barium-B as the checkpoint selected for the public Argon release, while Carbon represents a separate and potentially more capable iteration.

Carbon is reportedly being tested through Jetski, Google’s internal name associated with Antigravity. We recently discovered another unreleased Antigravity feature called Chief of Staff, an agent previously known as Concierge. Together, these developments point to Google’s broader focus on autonomous coding agents powered by increasingly capable Gemini models.

The comparison with Opus 5.5 is particularly noteworthy considering Anthropic’s current position in agentic coding. However, it remains unclear whether Carbon will become a future Argon update or a separate Gemini 4 release.

Argon’s wider rollout could potentially begin as soon as next week, although Google has not confirmed a date. With expectations surrounding Gemini 4 already high, its real-world coding performance and availability across Google’s products will be closely watched.

Sources and related context

• Google announces Gemini 4 Argon: Supports: Google's September 30 announcement confirms initial access for trusted cyber defenders, followed by paid API customers and Google AI Ultra subscribers.
• Business Insider reports on Google's internal Carbon testing: Supports: The report supports the employee comparison with Claude Opus 5.5, Carbon testing through Jetski, and Barium-B's selection as the public Argon checkpoint.