You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
ModelsArea: what it touches
New FeaturesKind: in v2.1.251,
New FeaturesSection of the release
What
When fast mode cannot be turned on or off, the message now says which of the three causes applied: a timeout, an explicit refusal, or the model changing while hooks that run before a model switch were still executing.
Evidence
Fast mode was not ${o}: the model changed while PreModelSwitch hooks ran; try again
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeAdded PreModelSwitch and PostModelSwitch hook events (block, confirm, or annotate a model switch); SessionStart resume hooks now receive…
