Fix Updates being forwarded even when not processable or causing no change (#17699)

* Fix Updates being forwarded even when not processable or causing no change

* Refactor and ensure status edit is strictly newer than last known edit

app/services/activitypub/process_status_update_service.rb

@@ -15,6 +15,8 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
     # Only native types can be updated at the moment
     return if !expected_type? || already_updated_more_recently?
 
+    last_edit_date = status.edited_at.presence || status.created_at
+
     # Only allow processing one create/update per status at a time
     RedisLock.acquire(lock_options) do |lock|
       if lock.acquired?
@@ -37,6 +39,8 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
         raise Mastodon::RaceConditionError
       end
     end
+
+    forward_activity! if significant_changes? && @status_parser.edited_at.present? && @status_parser.edited_at > last_edit_date
   end
 
   private
@@ -263,4 +267,12 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
     PollExpirationNotifyWorker.remove_from_scheduled(poll.id) if @previous_expires_at.present? && @previous_expires_at > poll.expires_at
     PollExpirationNotifyWorker.perform_at(poll.expires_at + 5.minutes, poll.id)
   end
+
+  def forward_activity!
+    forwarder.forward! if forwarder.forwardable?
+  end
+
+  def forwarder
+    @forwarder ||= ActivityPub::Forwarder.new(@account, @json, @status)
+  end
 end