feat: support view transitions

[pmelab]

Adjust the client side router to use startViewTransition if available and provide and example.

• Link navigation
• Programmatic navigation
• Browser prev/next buttons

Does not work in Firefox, since it does not support that API yet.
Also there is no automated test since I really have no idea how to test that.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
waku	✅ Ready (Inspect)	Visit Preview	Feb 4, 2025 5:07pm

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

[dai-shi]

Why do we need skipRefetch here?

[pmelab]

I took over conditions to not start the transition if it wouldn't change anything, but that's completely wrong here.

[pmelab]

I'm struggling to resolve the one remaining issue:

When clicking a broken link, we fall back to loading the RSC payload for 404 pages here:

waku/packages/waku/src/router/client.ts

Line 470 in b9031fe

return fetchRsc(encodeRoutePath('/404'));

I stepped through the debugger. The 404 data is there, and for the remaining process it should be the same as a regular route change. But for some reason we eventually end up here:

waku/packages/waku/src/minimal/client.ts

Line 280 in b9031fe

throw new Error('Invalid element: ' + id);

[pmelab]

More findings:

It seems like react rendering continues while startViewTransition is in progress and renders the non-existent page a second time. And thats where the error happens.