fix: gate client handler bounds for local (#1068)

crates/rmcp/Cargo.toml

@@ -238,6 +238,11 @@ required-features = [
 ]
 path = "tests/test_with_js.rs"
 
+[[test]]
+name = "test_local_client_handler"
+required-features = ["client", "local"]
+path = "tests/test_local_client_handler.rs"
+
 [[test]]
 name = "test_notification"
 required-features = ["server", "client"]

crates/rmcp/src/handler/client.rs

@@ -85,8 +85,8 @@ impl<H: ClientHandler> Service<RoleClient> for H {
     }
 }
 
-#[allow(unused_variables)]
+macro_rules! client_handler_methods {
-pub trait ClientHandler: Sized + Send + Sync + 'static {
+    () => {
         fn ping(
             &self,
             context: RequestContext<RoleClient>,
@@ -268,6 +268,19 @@ pub trait ClientHandler: Sized + Send + Sync + 'static {
         fn get_info(&self) -> ClientInfo {
             ClientInfo::default()
         }
+    };
+}
+
+#[allow(unused_variables)]
+#[cfg(not(feature = "local"))]
+pub trait ClientHandler: Sized + Send + Sync + 'static {
+    client_handler_methods!();
+}
+
+#[allow(unused_variables)]
+#[cfg(feature = "local")]
+pub trait ClientHandler: Sized + 'static {
+    client_handler_methods!();
 }
 
 /// Do nothing, with default client info.

crates/rmcp/tests/test_local_client_handler.rs

@@ -0,0 +1,16 @@
+use std::rc::Rc;
+
+use rmcp::ClientHandler;
+
+struct LocalClientHandler {
+    _state: Rc<()>,
+}
+
+impl ClientHandler for LocalClientHandler {}
+
+#[test]
+fn client_handler_accepts_non_send_sync_state_with_local_feature() {
+    fn assert_client_handler<T: ClientHandler>() {}
+
+    assert_client_handler::<LocalClientHandler>();
+}