Provide comprehensive migration tool

Describe the problem

I lot of svelte’s early supporters have bailed on this project due to the new routing system and recent breaking changes. While the reasoning behind these changes has already been decided, and the changes are permanent, a comprehensive migration tool should be provided.

Describe the proposed solution

npx svelte-migrate only has the routes subsection, but it also does a lot more. I think that this tool should try to be as comprehensive as possible, allowing anyone using any beta version of svelte to update to the current version. Where these updates need clear human intervention, a throw new Error("@migrate ...") might work, but otherwise this tool should just do it.

Alternatives considered

Long hours of work migrating from a cool framework to a slightly less cool newer version of said framework

Importance

i cannot use SvelteKit without it

Additional Information

No response

[benmccann]

Generally the way to do an incremental migration with Kit is just to migrate a few versions at a time instead of doing a big jump all at once. The version that introduced the routing change does take effort though

[Explosion-Scratch]

Ah, is there already an issue about incremental adoption of new features?

Not sure what you mean by this, but there’s a migration guide here: #5774

Like options in svelte.config.js where you can turn on and off various new features, like:

{kit: {legacy: {disableNewRouting: true, disablePageActions: true, disableOtherNewFeature: true}}}