vscode-extension-samples

I honestly don't see the issue here (Full disclosure: I work for Microsoft, but in professional services, not in product - and nevertheless fully expect to be downvoted to oblivion). If these aren't finished, that most likely means that they still haven't stabilized enough to go through the full support and release pipeline--that usually means documenting them, publishing a couple of reference development samples, doing a public announcement, i.e., the full nine yards of fostering adoption of the product feature. Which you typically will only do once the "preview" is stable and flexible enough to pass muster. I mean, it's not as if there isn't a huge API surface for the editor (the sample extensions repo is huge - https://github.com/microsoft/vscode-extension-samples), and there are already samples out there to extend the Copilot function

I too share your sentiment about VS Code. Its extension API[0] is extensive and approachable, often with examples[1] for each API. Just a small anecdote: At work, I found it frustrating not being able to quickly locate where views for Django API endpoints were, so I wrote a simple extension that took the output of django-extensions' show_urls, parsed it, and displayed a quick pick list of all API endpoints, upon which selecting an endpoint would open the file and reveal the exact line in which the view for it was defined. Implementing this did not take much effort (in fact, TypeScript and JSDoc make everything a lot simpler as it's clear to see what each function in the API does and what arguments they accept), and now this is something I use almost every day and greatly improves my satisfaction when navigating the codebase if not my prod