It looks like there may be two competing models of history:

stateTransitionHistory?: boolean; //true if the agent exposes status change history for tasks

optional history of status and Messages.

The text in both spots suggests that historical statuses will be available... but the data model says:

history?: Message[];

(And this matches what's in the json defs)

In other words, the history structure has messages but not statuses.

It would be good for history to look more like an actual status history, meaning an array of items like:

{
  state,
  timestamp,
  message[]
}