Inject history when object is refetched

lib/pleroma/object.ex

@@ -445,4 +445,26 @@ defmodule Pleroma.Object do
       "orderedItems" => []
     }
   end
+
+  def maybe_update_history(updated_object, orig_object_data, updated) do
+    if not updated do
+      updated_object
+    else
+      # Put edit history
+      # Note that we may have got the edit history by first fetching the object
+      history = Object.history_for(orig_object_data)
+
+      latest_history_item =
+        orig_object_data
+        |> Map.drop(["id", "formerRepresentations"])
+
+      new_history =
+        history
+        |> Map.put("orderedItems", [latest_history_item | history["orderedItems"]])
+        |> Map.put("totalItems", history["totalItems"] + 1)
+
+      updated_object
+      |> Map.put("formerRepresentations", new_history)
+    end
+  end
 end

lib/pleroma/object/fetcher.ex

@@ -26,8 +26,35 @@ defmodule Pleroma.Object.Fetcher do
   end
 
   defp maybe_reinject_internal_fields(%{data: %{} = old_data}, new_data) do
+    has_history? = fn
+      %{"formerRepresentations" => %{"orderedItems" => list}} when is_list(list) -> true
+      _ -> false
+    end
+
     internal_fields = Map.take(old_data, Pleroma.Constants.object_internal_fields())
 
+    remote_history_exists? = has_history?.(new_data)
+
+    # If the remote history exists, we treat that as the only source of truth.
+    new_data =
+      if has_history?.(old_data) and not remote_history_exists? do
+        Map.put(new_data, "formerRepresentations", old_data["formerRepresentations"])
+      else
+        new_data
+      end
+
+    # If the remote does not have history information, we need to manage it ourselves
+    new_data =
+      if not remote_history_exists? do
+        changed? =
+          Pleroma.Constants.status_updatable_fields()
+          |> Enum.any?(fn field -> Map.get(old_data, field) != Map.get(new_data, field) end)
+
+        new_data |> Object.maybe_update_history(old_data, changed?)
+      else
+        new_data
+      end
+
     Map.merge(new_data, internal_fields)
   end
 

lib/pleroma/web/activity_pub/side_effects.ex

@@ -431,28 +431,6 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
     )
   end
 
-  defp maybe_update_history(updated_object, orig_object_data, updated) do
-    if not updated do
-      updated_object
-    else
-      # Put edit history
-      # Note that we may have got the edit history by first fetching the object
-      history = Object.history_for(orig_object_data)
-
-      latest_history_item =
-        orig_object_data
-        |> Map.drop(["id", "formerRepresentations"])
-
-      new_history =
-        history
-        |> Map.put("orderedItems", [latest_history_item | history["orderedItems"]])
-        |> Map.put("totalItems", history["totalItems"] + 1)
-
-      updated_object
-      |> Map.put("formerRepresentations", new_history)
-    end
-  end
-
   defp maybe_update_poll(to_be_updated, updated_object) do
     choice_key = fn data ->
       if Map.has_key?(data, "anyOf"), do: "anyOf", else: "oneOf"
@@ -487,7 +465,7 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
 
       updated_object_data =
         updated_object_data
-        |> maybe_update_history(orig_object_data, updated)
+        |> Object.maybe_update_history(orig_object_data, updated)
         |> maybe_update_poll(updated_object)
 
       orig_object