In the book, you make a reference to
acts_as_paranoid, but given the simplicity and popularity: Category: Active Record Soft Delete - The Ruby Toolbox
I would suggest you to mention
discard instead. Also,
acts_as_paranoid has incompatibility issues with ActiveStorage: GitHub - ActsAsParanoid/acts_as_paranoid: ActiveRecord plugin allowing you to hide and restore records without actually deleting them.