@type t() :: %Synaptic.AgentHandle{
  instance_id: String.t() | nil,
  job_id: String.t() | nil,
  metadata: map(),
  run_id: String.t() | nil,
  service_id: String.t() | nil,
  target_type: :service | :instance | :task_ref | :job,
  task_ref_id: String.t() | nil,
  tenant_id: String.t() | nil
}