Unclear It is not clear which tasks use the model this rule chooses.
What
Claude Code has changed the rule for when it falls back to choosing a Haiku-class model by itself. It now does so only when all of these hold:
ANTHROPIC_SMALL_FAST_MODELis not setANTHROPIC_DEFAULT_HAIKU_MODELis not set- Claude Code is talking to Anthropic's own API directly, not through another cloud provider
- the main model is the default one
- a few further checks pass
If you set either variable, your choice is used instead of this fallback. Environment variables are named values set in your shell before Claude Code starts.
Why
This may change which model handles small or quick tasks for you, so the model you see used for those tasks may differ from before.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear which tasks use the model this rule chooses.