Stream HTTP responses to WebView2

I want to stream HTTP responses to WebView2. I don't think this is possible right now, so this is a feature request.

For example, I want to intercept a request and return server-sent events which the client can process per event.

For example, I want to intercept a request and return a chunked response which the client can process incrementally.

Repro

(Or how it could work)

Host C# code

async void WebResourceRequested(CoreWebView2 sender, CoreWebView2WebResourceRequestedEventArgs args)
{
  var stream = new InMemoryRandomAccessStream();
  var writer = new DataWriter(stream);

  var response = sender.Environment.CreateWebResourceResponse(
      Content: stream, // new AsyncEnumerableRandomAccessStream(results),
      StatusCode: 200,
      ReasonPhrase: "OK",
      Headers: string.Join('\n',
          $"Content-Type: text/event-stream",
          $"Cache-Control: no-cache",
          $"Connection: keep-alive"));

  args.Response = response;

  for (int i = 0; i < 4; i++)
  {
      writer.WriteString($"event: count\n");
      writer.WriteString($"data: {{ \"count\": {i} }}\n");
      writer.WriteString("\n");
      await writer.StoreAsync();
      await writer.FlushAsync();

      await Task.Delay(200);
  }

  // or maybe deferral should be completed earlier
  // but I can continue to write to the stream?
  deferral.Complete();
}

await view.EnsureCoreWebView2Async();
view.CoreWebView2.AddWebResourceRequestedFilter("my-example-url", CoreWebView2WebResourceContext.All);
view.CoreWebView2.WebResourceRequested += WebResourceRequested;

Client JavaScript code

fetch("my-example-url")
  .then((response) => response.body.pipeThrough(new TextDecoderStream()).getReader())
  .then(async (reader) => {
    console.log("Started");
    while (true) {
      const { value, done } = await reader.read();
      if (done) {
        console.log("Completed");
        break;
      }
      console.log("Received", value);
    }
    reader.releaseLock();
  })
  .catch(console.error);

Expected

I want the response to be streamed so the client can process each event as it's sent.

Started
Received event: count
data: { "count": 0 }

Received event: count
data: { "count": 1 }

Received event: count
data: { "count": 2 }

Received event: count
data: { "count": 3 }


Completed

For example, running the JavaScript client code with the url https://sse.dev/test will behave like this.

Actual

The response is buffered and becomes available to the client all-at-once.

Started
Received event: count
data: { "count": 0 }

event: count
data: { "count": 1 }

event: count
data: { "count": 2 }

event: count
data: { "count": 3 }


Completed

System info

• Microsoft.WindowsAppSDK 1.2.221209.1
• Microsoft.Windows.SDK.NET 10.00.19041.28
• Microsoft.WinUI 3.00.0.2212

AB#47606624