[kentonv]

You are probably thinking of Worker RPC, which is ocap-based: https://blog.cloudflare.com/javascript-native-rpc/

At present output gates operate on the scope of a single worker, blocking the output from being sent. It's easy to imagine, though, that we extend things so if you are sending a message to another worker (including a Durable Object), the message is sent immediately, but the destination worker becomes subject to the same output gate. Haven't done it yet but would definitely like to!