refactor(sacp)!: remove to_future_hack from tool_fn API

- Introduce JrResponder trait at jsonrpc level for background tasks
- Add Responder type parameter to JrConnectionBuilder and JrConnection
- Replace with_spawned usage in with_mcp_server with with_responder
- Refactor with_client to use run_until + try_join! instead of select!
- with_client now returns generic T instead of just ()
- tool_fn now uses FnMut + Future bounds instead of AsyncFn

BREAKING CHANGE: tool_fn no longer requires the to_future_hack parameter

Author: nikomatsakis

src/sacp-conductor/tests/mcp_integration/proxy.rs

@@ -34,7 +34,6 @@ impl Component for ProxyComponent {
                         result: format!("Echo: {}", params.message),
                     })
                 },
-                sacp::tool_fn!(),
             )
             .build();
 

src/sacp-conductor/tests/mcp_server_handler_chain.rs

@@ -82,7 +82,6 @@ impl Component for ProxyWithMcpAndHandler {
                         result: format!("Echo: {}", params.message),
                     })
                 },
-                sacp::tool_fn!(),
             )
             .build();
 

src/sacp-conductor/tests/scoped_mcp_server.rs

@@ -83,7 +83,9 @@ async fn test_scoped_mcp_server_through_session() -> Result<(), sacp::Error> {
 
 struct ScopedProxy;
 
-fn make_mcp_server<Role: JrRole>(values: &Mutex<Vec<String>>) -> McpServer<'_, Role>
+fn make_mcp_server<Role: JrRole>(
+    values: &Mutex<Vec<String>>,
+) -> McpServer<Role, impl sacp::JrResponder + use<'_, Role>>
 where
     Role: HasEndpoint<Agent>,
 {
@@ -102,17 +104,11 @@ where
                 values.extend(input.elements);
                 Ok(values.len())
             },
-            sacp::tool_fn!(),
-        )
-        .tool_fn(
-            "get",
-            "Get the collected values",
-            async |(): (), _cx| {
-                let values = values.lock().expect("not poisoned");
-                Ok(values.clone())
-            },
-            sacp::tool_fn!(),
         )
+        .tool_fn("get", "Get the collected values", async |(): (), _cx| {
+            let values = values.lock().expect("not poisoned");
+            Ok(values.clone())
+        })
         .build()
 }
 

src/sacp-conductor/tests/test_session_id_in_mcp_tools.rs

@@ -40,19 +40,18 @@ fn create_echo_proxy() -> Result<sacp::DynComponent, sacp::Error> {
                     acp_url: context.acp_url(),
                 })
             },
-            sacp::tool_fn!(),
         )
         .build();
 
     // Create proxy component
     Ok(sacp::DynComponent::new(ProxyWithEchoServer { mcp_server }))
 }
 
-struct ProxyWithEchoServer {
-    mcp_server: McpServer<'static, ProxyToConductor>,
+struct ProxyWithEchoServer<R: sacp::JrResponder> {
+    mcp_server: McpServer<ProxyToConductor, R>,
 }
 
-impl Component for ProxyWithEchoServer {
+impl<R: sacp::JrResponder + 'static> Component for ProxyWithEchoServer<R> {
     async fn serve(self, client: impl Component) -> Result<(), sacp::Error> {
         ProxyToConductor::builder()
             .name("echo-proxy")

src/sacp-rmcp/src/lib.rs

@@ -22,7 +22,7 @@
 
 use rmcp::ServiceExt;
 use sacp::mcp_server::{McpContext, McpServer, McpServerConnect};
-use sacp::{Agent, ByteStreams, Component, DynComponent, HasEndpoint, JrRole};
+use sacp::{Agent, ByteStreams, Component, DynComponent, HasEndpoint, JrRole, NullResponder};
 use tokio_util::compat::{TokioAsyncReadCompatExt, TokioAsyncWriteCompatExt};
 
 pub trait McpServerExt<Role: JrRole>
@@ -37,7 +37,7 @@ where
     fn from_rmcp<S>(
         name: impl ToString,
         new_fn: impl Fn() -> S + Send + Sync + 'static,
-    ) -> McpServer<'static, Role>
+    ) -> McpServer<Role, NullResponder>
     where
         S: rmcp::Service<rmcp::RoleServer>,
     {
@@ -67,12 +67,12 @@ where
                 name: name.to_string(),
                 new_fn,
             },
-            Box::pin(futures::future::ready(Ok(()))),
+            NullResponder,
         )
     }
 }
 
-impl<Role: JrRole> McpServerExt<Role> for McpServer<'_, Role> where Role: HasEndpoint<Agent> {}
+impl<Role: JrRole> McpServerExt<Role> for McpServer<Role> where Role: HasEndpoint<Agent> {}
 
 /// Component wrapper for rmcp services.
 struct RmcpServerComponent<S> {