Version 1.1.6 of the IndieAuth Client library for PHP is released! This update adds support for IndieAuth Server Metadata and additional endpoint discovery methods as part of the 2022-02-12 version of the IndieAuth specification. It is backwards compatible with sites that do not yet support the metadata endpoint.
I will be updating indiebookclub in the next few days to use this version. In my testing with it so far, everything has worked smoothly. I look forward to other IndieAuth implementations updating as well.