kind property
Kind is what this turn IS: message, tool-call, spawn, log, status, control or progress. Anything else is refused — the vocabulary is closed so a reader can branch on it.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
String? kind;