Under the hood
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A new helper function chooses between the small fast model and a project's configured model
What
A new function picks which model to use in a given situation. When called with a truthy argument, it prefers a session's configured projectsModel (after checking it's valid), falling back to a general default-model resolver if not set. When called without that argument, it instead prefers the "small fast model" setting (useSmallFastModel) when enabled, otherwise falling back to the same default-model resolver.
Why
This centralizes model-selection logic that previously may have been scattered, letting different parts of Claude Code consistently choose between a project-specific model and the small fast model depending on context.
Names in the bundleuseSmallFastModel
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The finding doesn't say which call sites use this new helper or in what user-visible situations it's invoked.