Google tests stronger Gemini 4 model as Argon rollout nears

Google is preparing to release its Gemini 4 model known internally as Argon while employees test a newer internal version called Carbon. The model was recently made available inside Google’s internal coding platform, Jetski, and staff messages described it as a notable step up for coding work.

One employee said Carbon “feels like Opus 5.5” for coding, comparing it with Anthropic’s strongest model for long-term agentic coding, while noting that more testing was needed. Earlier internal versions of Argon were generally well received, though one employee said they lagged on some coding tasks and compared them with Claude Opus 5.

Internal documents show Google has tested Gemini 4 models under the names Argon, Barium and Carbon, with Barium-B selected as the model that will be publicly known as Argon. It remains unclear whether Carbon will ship as an Argon update or as a separate Gemini 4 release.

Google said Argon delivered frontier performance on some coding and knowledge-work benchmarks, including legal and finance, and emphasized defensive cybersecurity. The company plans to make Argon available first to partners in its Fairwind Program before a wider public rollout.