Managed default
Auto
The managed lane's default. Omit model (or pass auto) and Boardwalk routes each agent() call to a strong default for that prompt, no key and no model menu. The response reports the model that actually served it, and you're billed at that model's normal rate, with no routing fee.
Model id
autoSelectionPer call
Routing fee$0
BillingAt cost
auto is a moving target by design: as stronger models ship, the default it resolves to improves without a change to your program. Pin a specific model when a call needs reproducibility, a known strength, or a price ceiling. See Inference or browse every model you can pin.