But vscode isn't open-source? It's open-core I believe. I remember trying vscodium but not everything was there that I had on vscode, and that mainly stem from extensions relying on the proprietary parts of vscode.

MIT license makes it open-source? As far as I know, you can't get vscode up and running from that repo. It requires some proprietary parts too.

Even the language server is proprietary, though the protocol is open.

I think open-core is better label.

Yes, an open source license makes a project open source.

Cursor took the code and modified it for their product, so it's at least open enough to be able to do that.

What makes it not count as open-core?

Umm it does have support for open/free/self-hosted models through either openrouter or by changing the oai endpoint (as long as you've got an openai compatible endpoint which is usually the case).