[Question] How to emit heartbeat/comments with Results.ServerSentEvents in .NET 10? #65103

We are migrating our application from .NET 9 to .NET 10 and since we have many SSE endpoints and we are testing the new Results.ServerSentEvents implementation with IAsyncEnumerable<T>.

Our infrastructure uses Nginx as a reverse proxy, which requires a periodic heartbeat (SSE comment lines starting with :) to prevent connection closure due to idle timeouts.

In our previous implementation, we were directly writing into the response buffer of HttpContext so we could manually mix data events and heartbeats into the stream.

With Results.ServerSentEvents handling the IAsyncEnumerable serialization automatically, we cannot find a way to inject these heartbeat frames.

1. Is there a built-in configuration to enable automatic heartbeats?
2. If not, Do you have any suggestion on what would be the best way to achieve the same using this new API?

Many thanks in advance!