About Svelte, on the svelte subreddit it was reported that GPT 5.2 is better at Svelte, perhaps because it has a more recent knowledge cutoff

But anyway you should set up the Svelte MCP

I take these early reports (less than a week or two after a major model release) with a grain of salt. It takes time to get to know a model, and maybe there's some selection bias in who's posting within 1-2 days of getting access.

(Although in this particular case, the very different knowledge cutoff makes it a lot easier to believe)