OptionalDurationSet on provider events.
OptionalElapsedSet on final events.
OptionalErrorSet on error events.
'provider' | 'fused' | 'reranked' | 'final' | 'error'
OptionalProviderSet on provider events (and on reranked, as the reranker's name).
OptionalResultSet on provider events: how many hits that provider returned, capped at MaxResults.
OptionalResultsSet on fused, reranked and final events. Always empty on a provider event: a provider's hits arrive
before the server's permission pass, so they are never streamed.
OptionalSourceSet on final events.
One event of a streaming search (
GraphQLSearchClient.StreamSearch), as theSearchStreamEventssubscription delivers it.