From https://once.com/writebook

app/models/edit.rb

@@ -0,0 +1,18 @@
+class Edit < ApplicationRecord
+  belongs_to :leaf
+  delegated_type :leafable, types: Leafable::TYPES, dependent: :destroy
+
+  enum :action, %w[ revision trash ].index_by(&:itself)
+
+  scope :sorted, -> { order(created_at: :desc) }
+  scope :before, ->(edit) { where("created_at < ?", edit.created_at) }
+  scope :after, ->(edit) { where("created_at > ?", edit.created_at) }
+
+  def previous
+    leaf.edits.before(self).last
+  end
+
+  def next
+    leaf.edits.after(self).first
+  end
+end