First off wanted to say thanks for writing this book! I’m new to clojure and this has been a great resource for exploring the clojure web-dev ecosystem!
I ran into an error while adding the login / logout buttons in chapter 6. We implement api/login earlier but we do not implement api/logout. Thus clicking the log-out button returns a 404 from the server and prevents the client-side success handler from executing.
It’s a fun exercise to implement it myself though 
EDIT: I realized an implementation was included in the accompanying source code (see guestbook-login for example). Perhaps it was intended to be included in the book as well