WEB: websocket + websocket-lanes as Carrier

src/maestro/generation.rs

@@ -246,11 +246,19 @@ impl RuntimeGeneration {
 
     /// Registers a session only while admission remains open.
     pub(crate) fn spawn_session<F>(&self, future: F) -> bool
+    where
+        F: Future<Output = ()> + Send + 'static,
+    {
+        self.try_spawn_session(future).is_ok()
+    }
+
+    /// Registers one session or returns its unpolled future to the caller.
+    pub(crate) fn try_spawn_session<F>(&self, future: F) -> Result<(), F>
     where
         F: Future<Output = ()> + Send + 'static,
     {
         let Some(_registration) = self.session_admission.try_register() else {
-            return false;
+            return Err(future);
         };
         let cancel = self.session_cancel.clone();
         self.sessions.spawn(async move {
@@ -259,7 +267,7 @@ impl RuntimeGeneration {
                 _ = future => {}
             }
         });
-        true
+        Ok(())
     }
 
     /// Closes admission while preserving already registered sessions.

src/maestro/orchestrator.rs

@@ -318,11 +318,8 @@ pub(super) async fn run_telemt_core(
     active_runtime_tx.send_replace(Some(active_runtime.clone()));
     runtime_tasks::mark_runtime_ready(&startup_tracker).await;
 
-    let listener_manager = listeners::ListenerManager::start(
-        bound,
-        active_runtime.clone(),
-        web_trace.clone(),
-    );
+    let listener_manager =
+        listeners::ListenerManager::start(bound, active_runtime.clone(), web_trace.clone());
     let reload_supervisor = reload_supervisor::ReloadSupervisor::spawn(
         active_runtime.clone(),
         reload_control,