> why forking VS Code when all this functionality could just be an extension, same as Copilot does?
Have you programmed extensions for VSCode before? While it seems like a fairy extensible system overall, the editor component in particular is very restrictive. You can add text (that's what extensions like ErrorLens and GitLens are doing), inlay hints, and on-hover popup overlays (those can only trigger on words, and not on punctuation). What Cursor does: the automatic diff-like views of AI suggestions with graphic outlines, floating buttons, and whatnot right on top of the text editing view - is not possible in vanilla VSCode.
This was originally driven by necessity of tighter control over editor performance. In its early days VSCode was competing with Atom - another extensible JS-powered editor from GitHub, and while Atom had an early lead due to larger extensions catalog VSCode ultimately won the race because they manged to maintain lower latency of their text editor component. Nowadays they still don't want to introduce extra extension points to it, because newer faster editors pop out all the time, too.
Have you programmed extensions for VSCode before? While it seems like a fairy extensible system overall, the editor component in particular is very restrictive. You can add text (that's what extensions like ErrorLens and GitLens are doing), inlay hints, and on-hover popup overlays (those can only trigger on words, and not on punctuation). What Cursor does: the automatic diff-like views of AI suggestions with graphic outlines, floating buttons, and whatnot right on top of the text editing view - is not possible in vanilla VSCode.
This was originally driven by necessity of tighter control over editor performance. In its early days VSCode was competing with Atom - another extensible JS-powered editor from GitHub, and while Atom had an early lead due to larger extensions catalog VSCode ultimately won the race because they manged to maintain lower latency of their text editor component. Nowadays they still don't want to introduce extra extension points to it, because newer faster editors pop out all the time, too.