Isomorphic JS/TS Functions Orchestrator (github.com)

But why

Creating a custom DSL for the transition action is really bad IMO.

It is very opaque, and error prone. It would be better to use lambdas, and if you want serialization, maybe a builder

Some kind of a state machine.?

It's not clear to me what problem this is trying to solve

Edit: Ok so this is just a dag cell evaluator on top of jsonata [1] (that looks like to be a small data processing language to evaluate expressions)

[1]: https://github.com/jsonata-js/jsonata

You may want to package this a bit better. I didn't quite understand what problem this is solving.