In working on the web client code, Kristo discovered that when a user who is not signed in to a library clicks on the Download button, a sign-in dialog is displayed instead of the download proceeding. Kristo pointed to this example: http://simplye-dev-cm.amigos.org/xyzlib/works/713/fulfill/2

In a discussion in the Slack devops channel, Amy commented that she thinks this may be an unintended consequence (and a change of previous behavior) of her change to the Download button that specifies a fulfill action so that the download is records in circulationevents. And the fulfill branch of code may be forcing a sign-in in cases where it's not needed.