Two rivals, one picker

Google updated its Antigravity coding workspace on October 3, putting Anthropic's flagship Claude Opus 5.5 and Claude Sonnet 5.5 into the model selector, both in their thinking variants. Antigravity is Google's agentic IDE: it plans, writes, and tests code across repositories. Now, inside Google's own developer tool, Anthropic's newest models sit alongside Gemini, competing for the same prompts.

The paywall, and the holes in it

Both Claude 5.5 models are reserved for paying Google AI Pro and Ultra subscribers. Free accounts don't qualify. Neither do Google AI Plus accounts, nor trial Pro subscriptions. Enterprise accounts are excluded too, which is the odd one: the tier that pays the most per seat can't touch the flagship models inside Google's own coding tool. Meanwhile the older Claude 4.6 models and the open-weight GPT-OSS-120B are marked for removal on November 2, so anyone still pointed at them has a month to migrate.

Distribution is the product now

The interesting part isn't which model wins a benchmark. It's that Google would rather stock a competitor's models in its own tool than keep the shelf Gemini-only. Antigravity keeps developers inside Google's subscription; losing them to Claude Code would cost more than the licensing. Anthropic, for its part, keeps collecting revenue from people who never signed up for an Anthropic account. Labs used to compete on weights. Increasingly, they compete on where the weights are served.

What to record

If you compare Antigravity runs across accounts, the model and the subscription now both belong in the test notes. A result produced with an eligible Claude 5.5 entitlement may not reproduce on a Free, Plus, trial-Pro, or Enterprise account. And with Claude 4.6 retiring November 2, pinned model selections have an expiry date. Check the picker, and the plan, before trusting the output.

Sources

  1. [1] PC-Tablet, “Google Antigravity Adds Anthropic Claude Opus 5.5 and Sonnet 5.5 for Paid Subscribers”Read source
  2. [2] Let's Data Science, “Google Antigravity Adds Claude 5.5 to Paid Tiers”Read source