Digital identity backend architecture: the decisions tutorials skip When I was studying Computer Science at UBA, there were classes I'd walk into straight from work, still in my office clothes. One night I showed up late to an operating systems lecture and the professor was talking about permissions and users. I'd spent that same afternoon breaking a Linux hosting server with a chmod -R 777 that seemed harmless at the time. The professor was explaining the theoretical model. I already knew what it cost not to understand it. I think about that every time I read an auth tutorial that ends with "your login system is up and running!" Sure, it works. Until someone changes roles, logs out from one device, or you need to invalidate a token you issued 40 minutes ago. My thesis : auth tutorials show you the happy path. The real problems in a digital identity backend show up in three places that almost never get covered: credential revocation, state-change propagation, and the trust model between services.…