sausage-plugin part 2: import! with typed clients (sausage_interface::client_rs), TCP endpoints with rpc.endpoint, examples

Part 1 fixes: complete stdout writes, buffered stdin, Rust type names
in schemas, enum variant docs, -32603 for serde errors in handlers,
crate docs and modules. End-to-end check of a generated consumer through
a fake core.

sdk/src/imports.rs

@@ -0,0 +1,46 @@
+//! Typed outgoing calls and statically registered imported interfaces.
+use crate::{Call, Result};
+use serde_json::Value;
+use std::{future::IntoFuture, marker::PhantomData};
+
+/// An imported provider document registered by `import!`.
+#[doc(hidden)]
+pub struct Import {
+    /// The provider name.
+    pub name: &'static str,
+    /// Its complete OpenRPC document.
+    pub document: &'static str,
+}
+inventory::collect!(Import);
+
+/// An outgoing call whose result decodes to a generated Rust type.
+pub struct TypedCall<T> {
+    call: Call,
+    result: PhantomData<T>,
+}
+impl<T> TypedCall<T> {
+    /// Wrap an untyped call without sending it yet.
+    pub fn new(call: Call) -> Self {
+        Self {
+            call,
+            result: PhantomData,
+        }
+    }
+    /// Detach the child process from its caller.
+    pub fn detach(mut self) -> Self {
+        self.call = self.call.detach();
+        self
+    }
+    /// Receive progress notifications while the call runs.
+    pub fn on_notify(mut self, f: impl FnMut(&str, Value) + 'static) -> Self {
+        self.call = self.call.on_notify(f);
+        self
+    }
+}
+impl<T: serde::de::DeserializeOwned + 'static> IntoFuture for TypedCall<T> {
+    type Output = Result<T>;
+    type IntoFuture = futures::future::LocalBoxFuture<'static, Result<T>>;
+    fn into_future(self) -> Self::IntoFuture {
+        Box::pin(async move { Ok(serde_json::from_value(self.call.await?)?) })
+    }
+}