Traditional route appears to work

Beginnings of dylib extensions, entirely untestted

orchid-extension/src/tokio.rs

@@ -2,9 +2,15 @@ use std::rc::Rc;
 
 use crate::entrypoint::ExtensionBuilder;
 use crate::ext_port::ExtPort;
-
+/// Run an extension inside a Tokio localset. Since the extension API does not
+/// provide a forking mechanism, it can safely abort once the localset is
+/// exhausted. If an extension absolutely needs a parallel thread, it can import
+/// and call [tokio::task::spawn_local] which will keep alive the localset and
+/// postpone the aggressive shutdown, and listen for the [Drop::drop] of the
+/// value returned by [crate::system_ctor::SystemCtor::inst] to initiate
+/// shutdown.
 #[cfg(feature = "tokio")]
-pub async fn tokio_main(builder: ExtensionBuilder) {
+pub async fn tokio_main(builder: ExtensionBuilder) -> ! {
 	use tokio::io::{stderr, stdin, stdout};
 	use tokio::task::{LocalSet, spawn_local};
 	use tokio_util::compat::{TokioAsyncReadCompatExt, TokioAsyncWriteCompatExt};
@@ -21,4 +27,5 @@ pub async fn tokio_main(builder: ExtensionBuilder) {
 		});
 	});
 	local_set.await;
+	std::process::exit(0)
 }