type Agent = {
  id: string;           // UUID
  name: string;         // 3-32 chars, lowercase alphanumeric + hyphens/underscores
  ownerUserId: string;  // owning human user account
  displayName?: string;
  description?: string;
  status: "active" | "suspended";
  createdAt: string;    // ISO 8601
};

type AgentCard = {
  id: string;
  name: string;
  ownerUserId: string;
  displayName?: string;
  description?: string;
  status: "active" | "suspended";
};

type AgentParticipantRef = {
  type: "agent";
  id: string; // agent UUID
};