@type t() :: %Parlora.BackendRequest{
  context: Parlora.ContextSnapshot.t(),
  deadline_at_us: integer() | nil,
  delegation_id: String.t() | nil,
  id: String.t(),
  input: map(),
  metadata: map(),
  provider_generation: non_neg_integer(),
  task_id: String.t(),
  task_revision: pos_integer()
}