@plain-leather-21357 I've just got an end-to-end test running for the Rust side which does a whole ExecuteRequest-GetOperation-ExecuteResponse chain. This message format requires a depressing number of serializations of the same protos into bytes 😞 A lot of that's accidental from the Rust proto bindings (they handle Any pretty badly), but... I suspect I may end up hacking in some ugly memoization or byte-slice-sharing or something somewhere. (Not in the short term, but I suspect it will become a noticeable effect at some point...)