The first two systems I worked with using InterSystems technology were a PDP-11 running M11+ and a VAX 11/750 running M/VX. Too many years ago to count! 😊
Since then I've used most, if not all, InterSystems products up to IRIS and HealShare today.
I'm italian living in Switzerland and I work as Senior Consultant at GAIVOTA consultin SA, we provide professional services for InterSystems and other technologies.
Curiosity: apart from DC, I don't have ANY social account! 😁
There is no such a stream you are looking for.
Data is sent to the browser (via WEB Gateway and WEB Server) as you write it from your CSP page/application, IS NOT held in a stream and sent "at the end" (what's the end BTW?).
Here is the corresponding (as per @Stephen Canzano post) IRIS documentation (no password required):
I think/guess you are using the wrong port number in vs code.
Vs code uses the web server port to connect to IRIS. What port do you use to connect to the IRIS Management Portal? Likely you are using port 80 and/or 443, the same port should be used in vs code.