Interface CompletionRoute

The turn's messages so far; the last user message is the router's task hint.

Caller chain. Undefined builds the policy-aware chain from the environment; an empty array disables fallback. Either is resolved once, as generateText's walk resolves its chain: entries naming an excluded model or lacking an explicitly required capability are passed over, and so is the policy chain's entry for the first model.

Credentials for the primary only; fallback hops read the environment, as streamText's walk does. Set in the gateway defaults beside a provider or model, they are for that provider: a turn that names another provider does not take them.

The call's own effort, cache and output budget, from which each fallback hop's overrides are derived.

Called when the turn moves to a hop after the primary.

Called for every hop that could not start (initialisation failure or open circuit).

Called for every chain entry the walk passes over without an attempt: an excluded model, a missing required capability, the policy chain's entry for the first model, a refill no standing leg is owed, a Claude leg after a refusal.