pub const ARTIFACT_EVENT_KIND: &str = "artifact";Expand description
The one bus.emit kind this backend reserves: an emit under it stages
a named part instead of completing the invocation (GH #86).
Payload shape: { name = "<part>", content = <any> }. name is
required. Reaching VerdictChannel::Part from a script means staging
{ name = "verdict", content = "PASS" } before the terminal emit.