Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
ModelsArea: what it touches
Internal ChangesKind: in v2.1.280,
Internal ChangesSection of the release
What
The table Claude Code uses to track the newest model in each family, along with fast-mode and model-switching logic, now points to claude-opus-5-5 instead of claude-opus-5 as the latest Opus model.
Why
This means features that automatically pick the newest Opus model, such as fast mode or model switching, will now resolve to Opus 5.5 instead of the previous Opus model.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeAdded Claude Opus 5.5 (claude-opus-5-5), now the default Opus model — 1M context, $4/$20 per Mtok with $0.20/Mtok cache reads
