I am curious though: why roll your own? It seems like the only real differences are a) URLs/file extensions in the module names, and b) some type declarations for the system APIs (which I'd think just come down to some .d.ts files, not custom LSP logic). Microsoft's TypeScript language server is a wonder of engineering, and I doubt any small independent team would ever be able to go toe-to-toe with it. Seems like a waste to forego that if there's any possibility of utilizing it. A minimal fork maybe, if nothing else?
Well I'm glad to hear it's a priority. Best of luck, and I'll try to check in periodically and see how things are coming along! I would very much like to see this project succeed :)
Deno also does more stuff than just providing Type definitions, embedding TypeScript and doing module resolution; it's a complete toolset -- there's things that we can cover having our own LSP that the TypeScript LSP can't. Linting, formatting, testing etc.