Grepping through source, it looks like $SCTL_KEY and $SCTL_ENVELOPE are the only two env vars supported. It would be nice if $SCTL_ENVELOPE was documented. I can do this if you want, but please confirm that these are in fact the only two environment variables sctl cares about.

We need a backend compiler for C#. We don't know if there is something like JavaPoet for C#, but because types are relatively simple, it might make sense to just do it manually.

An example implementation for Java can be found here: io.vlingo.schemata.codegen.backend.java.JavaBackend