Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
ModelsArea: what it touches
Internal ChangesKind: in v2.1.280,
Internal ChangesSection of the release
What
The system prompt's sentence about fast mode (toggled with /fast) dropped the qualifier that it's "available on Opus 5/4.8," now simply saying it can be toggled with /fast. Separately, the code that picks a default model for the fast-mode picker no longer hardcodes claude-opus-5; it now calls a function to determine the current model instead.
Why
Together these mean fast mode's model selection is no longer pinned to a fixed model name in either the prompt text or the underlying default-model logic.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeChanged /fast's footer to name Space as the toggle key
