I've been working on Enterprise Access Control (EACL) in my spare time, an embedded Datalog-based library with a uniform declarative Clojure API that lets you write grant/deny ACL rules in the shape: Who, What, Why, When, Where & How that goes a little further than Role & Attribute. Link: https://github.com/theronic/eacl
Will do a Show HN when I fix all the bugs and get it fast enough.
Tokens are an interesting approach to future-proof a young application against having to rebuild auth internally. I like your up-front Pricing Philosophy section.