If they recreated it from scratch though, I don’t see what was stolen. Unless they incorporated your implementation somehow, I can’t see how this rises to stealing. There can be many competing implementations towards the same spec, and using one over the other is not necessarily theft.

I’m kind of confused. What work did they take? From the communications, it looks like you wrote some code, it wasn’t accepted, and Leah wrote their own implementation, from scratch. Is that not true? Unless they based their work off your code somehow, I don’t see how anything was stolen, potential dickishness from the maintainer aside.