ActionKeyProvider

Adopted by collectors that supply an actionKey directly rather than contributing to formData.

When actionKey is non-null the collector is considered ready to submit and its event type is used as the DaVinci eventType. When actionKey is null the collector is not yet ready, regardless of what Collector.payload returns.

Used by the FIDO error path to propagate WebAuthn DOMException names to the DaVinci server, and by SubmitCollector/FlowCollector to signal the user's chosen action.