test(sync): audit browser recovery paths

examples/kanban/src/main.rs

@@ -842,6 +842,7 @@ async fn sync_acknowledgements(
         .get("reconnect")
         .filter(|value| !value.is_empty())
         .cloned();
+    let persistent_stream = reconnect_key.is_some();
 
     let mut sync = state.sync.lock().unwrap();
     if let Some(key) = reconnect_key {
@@ -921,22 +922,26 @@ async fn sync_acknowledgements(
     };
     drop(sync);
     let heartbeat_interval = state.acknowledgement_heartbeat_interval;
-    let heartbeat = stream::unfold(heartbeat_interval, |interval| async move {
-        tokio::time::sleep(interval).await;
-        Some((
-            Ok(Event::default()
-                .event("heartbeat")
-                .data("{\"status\":\"ok\"}")),
-            interval,
-        ))
-    });
-    Ok(
-        Sse::new(stream::iter(events).chain(heartbeat).boxed()).keep_alive(
-            KeepAlive::new()
-                .interval(heartbeat_interval)
-                .text("heartbeat"),
-        ),
-    )
+    let event_stream = stream::iter(events).boxed();
+    let response_stream = if persistent_stream {
+        let heartbeat = stream::unfold(heartbeat_interval, |interval| async move {
+            tokio::time::sleep(interval).await;
+            Some((
+                Ok(Event::default()
+                    .event("heartbeat")
+                    .data("{\"status\":\"ok\"}")),
+                interval,
+            ))
+        });
+        event_stream.chain(heartbeat).boxed()
+    } else {
+        event_stream
+    };
+    Ok(Sse::new(response_stream).keep_alive(
+        KeepAlive::new()
+            .interval(heartbeat_interval)
+            .text("heartbeat"),
+    ))
 }
 
 fn registry(state: Arc<AppState>) -> impl DispatchRegistry {