@Pietro Di Leo 
If you find Wireshark intimidating you can use the Web Gateway's HTTP trace facility. If you're using Wireshark and the server is on the same machine as VS Code select the loopback capture device and add an http filter. This will help you filter out unwanted packets. If you use the Web Gateway's HTTP Trace, you can simply turn it on, attempt to save the class, turn the trace off, and then click refresh to see all the packets. You will be looking for a PUT request to the /api/atelier/v#/doc/<class_name> endpoint. We want to see what the full response is to that request.

@Pietro Di Leo 
That error is a red herring. That's coming from the Codeium AI extension which doesn't like our isfs URI format. This will not affect saving the files on the server. The best way to determine why your server saves are failing would be to get a network trace using a tool like Wireshark or the Web Gateway's HTTP trace tool.

@Pietro Di Leo 
That error has nothing to do with compilation. It didn't even get that far. VS Code tried to save that file on the server, but it failed. There should be an error in the ObjectScript Output channel. If not, a network trace will show us the HTTP error response.