The target agent name requested by the model.
Agent catalog (AIEngine.Instance.Agents).
Calling user whose view/run permissions gate target resolution and candidate discovery.
Ordered list of agent IDs that have already handed this user turn on, oldest first.
OptionalHostOptional host allow-list of agent IDs (HostAllowedAgentIDs(data)).
The ID of the agent requesting the handoff.
Inputs for ResolveHandoffTarget.