lib/pleroma/user.ex

@@ -2568,6 +2568,19 @@ defp maybe_load_followed_hashtags(%User{} = user) do
     %{user | followed_hashtags: followed_hashtags}
   end
 
+  def followed_hashtags(%User{followed_hashtags: follows})
+      when is_list(follows),
+      do: follows
+
+  def followed_hashtags(%User{} = user) do
+    {:ok, user} =
+      user
+      |> maybe_load_followed_hashtags()
+      |> set_cache()
+
+    user.followed_hashtags
+  end
+
   def follow_hashtag(%User{} = user, %Hashtag{} = hashtag) do
     Logger.debug("Follow hashtag #{hashtag.name} for user #{user.nickname}")
     user = maybe_load_followed_hashtags(user)

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -933,6 +933,21 @@ defp restrict_recipients(query, recipients, user) do
     )
   end
 
+  defp restrict_recipients_or_hashtags(query, recipients, user, nil) do
+    restrict_recipients(query, recipients, user)
+  end
+
+  defp restrict_recipients_or_hashtags(query, recipients, user, hashtag_ids) do
+    from(
+      [activity, object] in query,
+      join: hto in "hashtags_objects",
+      on: hto.object_id == object.id,
+      where:
+        (hto.hashtag_id in ^hashtag_ids and ^Constants.as_public() in activity.recipients) or
+          fragment("? && ?", ^recipients, activity.recipients)
+    )
+  end
+
   defp restrict_local(query, %{local_only: true}) do
     from(activity in query, where: activity.local == true)
   end
@@ -1380,7 +1395,7 @@ def fetch_activities_query(recipients, opts \\ %{}) do
       |> maybe_preload_report_notes(opts)
       |> maybe_set_thread_muted_field(opts)
       |> maybe_order(opts)
-      |> restrict_recipients(recipients, opts[:user])
+      |> restrict_recipients_or_hashtags(recipients, opts[:user], opts[:hashtags])
       |> restrict_replies(opts)
       |> restrict_since(opts)
       |> restrict_local(opts)

lib/pleroma/web/mastodon_api/controllers/timeline_controller.ex

@@ -41,6 +41,11 @@ defmodule Pleroma.Web.MastodonAPI.TimelineController do
 
   # GET /api/v1/timelines/home
   def home(%{assigns: %{user: user}} = conn, params) do
+    followed_hashtags =
+      user
+      |> User.followed_hashtags()
+      |> Enum.map(& &1.id)
+
     params =
       params
       |> Map.put(:type, ["Create", "Announce"])
@@ -50,6 +55,7 @@ def home(%{assigns: %{user: user}} = conn, params) do
       |> Map.put(:announce_filtering_user, user)
       |> Map.put(:user, user)
       |> Map.put(:local_only, params[:local])
+      |> Map.put(:hashtags, followed_hashtags)
       |> Map.delete(:local)
 
     activities =