Upstream original followbot implementation

config/config.exs

@@ -409,6 +409,8 @@
   threshold: 604_800,
   actions: [:delist, :strip_followers]
 
+config :pleroma, :mrf_follow_bot, follower_nickname: nil
+
 config :pleroma, :rich_media,
   enabled: true,
   ignore_hosts: [],

lib/pleroma/web/activity_pub/mrf/follow_bot_policy.ex

@@ -0,0 +1,41 @@
+defmodule Pleroma.Web.ActivityPub.MRF.FollowBotPolicy do
+  @behaviour Pleroma.Web.ActivityPub.MRF
+  alias Pleroma.User
+  alias Pleroma.Web.CommonAPI
+  require Logger
+
+  @impl true
+  def filter(message) do
+    Task.start(fn ->
+      follower_nickname = Pleroma.Config.get([:mrf_follow_bot, :follower_nickname])
+
+      with %User{} = follower <- User.get_cached_by_nickname(follower_nickname),
+           %{"type" => "Create", "object" => %{"type" => "Note"}} <- message do
+        to = Map.get(message, "to", [])
+        cc = Map.get(message, "cc", [])
+        actor = [message["actor"]]
+
+        Enum.concat([to, cc, actor])
+        |> List.flatten()
+        |> User.get_all_by_ap_id()
+        |> Enum.each(fn user ->
+          Logger.info("Checking if #{user.nickname} can be followed")
+
+          with false <- User.following?(follower, user),
+               false <- user.locked,
+               false <- (user.bio || "") |> String.downcase() |> String.contains?("nobot") do
+            Logger.info("Following #{user.nickname}")
+            CommonAPI.follow(follower, user)
+          end
+        end)
+      end
+    end)
+
+    {:ok, message}
+  end
+
+  @impl true
+  def describe do
+    {:ok, %{}}
+  end
+end