Mountain ViewGoogle employees say Gemini 4’s Carbon feels like Opus 5.5.

The evidence is staff impressions on Jetski, Google’s internal coding platform, not benchmarks.

Google’s internal Barium-B build was chosen to launch publicly as Argon, so code names do not match release names.

One employee said more testing is needed, and Google declined to comment.

Google has not said whether Carbon ships as an Argon update or a separate model.

How each outlet framed it
Zhidx
relies on Business Insider staff quotes that Carbon 'feels like Opus 5.5' and notes the internal-codename-to-public-name mismatch

Sources: Zhidx