tl;dr: SvelteKit 3.0 ships as an incremental release focused on polish and type safety, with an `npx sv migrate sveltekit-3` command to automate upgrades. Breaking changes include moving config to `vite.config.ts`, replacing the `$lib` alias with the standard `#lib` subpath import, improved environment variables, less boilerplate for service workers, and better error handling. Remote functions for type-safe client-server communication are the team's next priority but aren't ready yet, as they depend on the still-experimental Async Svelte.