Nova should be providing all the notifications the language server should need to track new files, but you have to be able to tap into the RPC communication to diagnose. Does you language server offer an RPC logging?
A truly generic solution would be to stick a proxy between Nova and the language server. Without googling anything first, I’d poke at haproxy or nginx at the tcp level, siphoning everything that goes through to a log file…
For the TypeScript extension I’ve used a simple shell script and tee to see what’s being sent back and forth. It doesn’t always work but might be a starting place.
Based on my interpretation of the LSP spec, the server is primarily in charge of indexing behavior. I’d expect it should be based on proper capability registration and notifications for the DidCreateFile notification.