flezha

https://github.com/flezha/flezha

Author Flezha relays in Ruby: flow and steps classes over the same shared kernel the Rust, Java, Node and Elixir SDKs drive. Transport, ordering, per-cell exclusivity, durability, retries, timers, credit and the steps driver all live in the core; this gem brings the authoring surface, the MessagePack codec, and a thread host that releases the GVL around every blocking core call.