From e32ab8aef278ebcef7ecbc9ae67f417b6862cff9 Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Tue, 14 Oct 2025 22:59:15 +0200
Subject: [PATCH 1/2] DB prune: Check if user follows hashtag with no objects
 before deletion

---
 changelog.d/prune-hashtag-follow-3376.fix | 1 +
 lib/mix/tasks/pleroma/database.ex         | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/prune-hashtag-follow-3376.fix

diff --git a/changelog.d/prune-hashtag-follow-3376.fix b/changelog.d/prune-hashtag-follow-3376.fix
new file mode 100644
index 000000000..cdb4e9a79
--- /dev/null
+++ b/changelog.d/prune-hashtag-follow-3376.fix
@@ -0,0 +1 @@
+DB prune: Check if user follows hashtag with no objects before deletion
diff --git a/lib/mix/tasks/pleroma/database.ex b/lib/mix/tasks/pleroma/database.ex
index e52b5e0a7..396536827 100644
--- a/lib/mix/tasks/pleroma/database.ex
+++ b/lib/mix/tasks/pleroma/database.ex
@@ -226,7 +226,12 @@ defmodule Mix.Tasks.Pleroma.Database do
     DELETE FROM hashtags AS ht
     WHERE NOT EXISTS (
       SELECT 1 FROM hashtags_objects hto
-      WHERE ht.id = hto.hashtag_id)
+      WHERE ht.id = hto.hashtag_id
+    )
+    AND NOT EXISTS (
+      SELECT 1 FROM user_follows_hashtag ufh
+      WHERE ht.id = ufh.hashtag_id
+    )
     """
     |> Repo.query()
 

From ef7be0a1e513841beba15ccce6b6211b7369332a Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Wed, 15 Oct 2025 23:14:52 +0200
Subject: [PATCH 2/2] DB prune: Add test for hashtags

---
 test/mix/tasks/pleroma/database_test.exs | 34 ++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/test/mix/tasks/pleroma/database_test.exs b/test/mix/tasks/pleroma/database_test.exs
index 19df17b60..5b567325c 100644
--- a/test/mix/tasks/pleroma/database_test.exs
+++ b/test/mix/tasks/pleroma/database_test.exs
@@ -8,6 +8,7 @@ defmodule Mix.Tasks.Pleroma.DatabaseTest do
 
   alias Pleroma.Activity
   alias Pleroma.Bookmark
+  alias Pleroma.Hashtag
   alias Pleroma.Object
   alias Pleroma.Repo
   alias Pleroma.User
@@ -550,6 +551,39 @@ defmodule Mix.Tasks.Pleroma.DatabaseTest do
 
       assert length(activities) == 3
     end
+
+    test "it prunes hashtags with no objects associated", %{old_insert_date: old_insert_date} do
+      user = insert(:user)
+
+      {:ok, hashtag_post_activity} =
+        CommonAPI.post(user, %{status: "morning #cofe", local: true})
+
+      hashtag_post_object = Object.normalize(hashtag_post_activity)
+
+      {:ok, hashtag_post2_activity} =
+        CommonAPI.post(user, %{status: "morning #cawfee", local: true})
+
+      hashtag_post2_object = Object.normalize(hashtag_post2_activity)
+
+      hashtag_post_object
+      |> Ecto.Changeset.change(%{updated_at: old_insert_date})
+      |> Repo.update!()
+
+      hashtag_post2_object
+      |> Ecto.Changeset.change(%{updated_at: old_insert_date})
+      |> Repo.update!()
+
+      # Test whether hashtags with follow relationships are kept
+      User.follow_hashtag(user, Hashtag.get_by_name("cofe"))
+
+      assert length(Repo.all(Hashtag)) == 2
+      assert length(Repo.all(Object)) == 2
+
+      Mix.Tasks.Pleroma.Database.run(["prune_objects"])
+      assert length(Repo.all(Hashtag)) == 1
+      assert length(Repo.all(Object)) == 0
+      assert Repo.one(Hashtag) |> Map.fetch!(:name) == "cofe"
+    end
   end
 
   describe "running update_users_following_followers_counts" do