FEATURE: reassign on "move to inbox"

config/locales/server.en.yml

@@ -6,7 +6,7 @@ en:
     unassign_creates_tracking_post: "If you unassign a topic a whisper or small action will be created to track change"
     assign_self_regex: "Regex that needs to pass for self assign. Example 'my list'"
     assign_other_regex: "Regex that needs to pass for assigning topics to others via mention. Example 'your list'."
-    unassign_on_group_archive: "When a message is archived by a group, unassign message"
+    unassign_on_group_archive: "When a message is archived by a group, unassign message (reassign if moved back to inbox)"
     unassign_on_close: "When a topic is closed unassign topic"
   discourse_assign:
     assigned_to: "Topic assigned to @%{username}"

plugin.rb

@@ -348,11 +348,30 @@ SQL
     ::TopicAssigner.auto_assign(post, force: true)
   end
 
+  on(:move_to_inbox) do |info|
+    if SiteSetting.unassign_on_group_archive && info[:group]
+      if topic = info[:topic]
+        if user_id = topic.custom_fields["prev_assigned_to_id"]
+          if user = User.find_by(id: user_id.to_i)
+            assigner = TopicAssigner.new(topic, Discourse.system_user)
+            assigner.assign(user, silent: true)
+          end
+        end
+      end
+    end
+  end
+
   on(:archive_message) do |info|
     if SiteSetting.unassign_on_group_archive && info[:group]
-      assigner = TopicAssigner.new(info[:topic], Discourse.system_user)
-      # not forcing silent cause archive leaves no trace
-      assigner.unassign
+      topic = info[:topic]
+      if user_id = topic.custom_fields["assigned_to_id"]
+        if user = User.find_by(id: user_id.to_i)
+          topic.custom_fields["prev_assigned_to_id"] = user.id
+          topic.save
+          assigner = TopicAssigner.new(topic, Discourse.system_user)
+          assigner.unassign(silent: true)
+        end
+      end
     end
   end