akkoma-cachapa/lib/pleroma/web/activity_pub/mrf/hellthread_policy.ex

defmodule Pleroma.Web.ActivityPub.MRF.HellthreadPolicy do
  @behaviour Pleroma.Web.ActivityPub.MRF

  @impl true
  def filter(object) do
    policy = Pleroma.Config.get(:mrf_hellthread)

    if length(object["to"]) + length(object["cc"]) > Keyword.get(policy, :threshold) do
      {:reject, nil}
    else
      {:ok, object}
    end
  end
end