Function generate 

pub fn generate(
    request: CanonicalRequest,
    config: ResolvedConfig,
    host: &Host<'_>,
) -> impl Iterator<Item = Event>

Generate against a resolved config (arch §1): drive ONE round-trip and yield the canonical event stream, terminated by a single End. THE pure typed core — run wraps it in byte I/O, an embedder consumes the events directly. The model SEED is resolved against the per-provider cache here (a local file read via host.cache, model-discovery §5.2), then the request is encoded, authenticated, and sent over the one Transport. Every failure is an in-band Event::Error, so the call is total. This is the normalized-in / canonical-out composition — [send_encoded] (the request half) then [canonical_events] (the response half); the --raw=out variant reuses send_encoded under a RawSink (arch §5.4, §13.14).