## Description
The goal is to reduce CLS on collapsed/expanded state of Lexical blocks.
That state is stored as "preferences" and is different for each user.
As Payload has been working so far, if the state of a Lexical block was
"collapsed", it was rendered expanded, and when the correct state was
obtained from the server, it was collapsed producing a CLS with a poor
UX.
My original idea was to get the correct state on the first render.
Talking to @AlessioGr and @jmikrut, we saw that this can be a bit
difficult or challenging, since the feature on the server does not have
access to the Payload object, nor to the user who is making the request.
I was instructed to mimic the behavior of blocks not in Lexial
(`\ui\src\fields\Collapsible\index.tsx`). There the blocks are rendered
after the collapse/expand state is obtained in a useEffect.
In the following video, the case where the first block is collapsed is
shown, rendering everything with a "fast 4G" connection throttle.
https://github.com/user-attachments/assets/078e37c7-6540-4183-a266-bd751cc9d78e
Yes, it's a slight improvement over current behavior. But it could be
much better. There are request waterfalls several levels deep, and
plenty of CLS still.
Unless there is some very big tradeoff that I'm not aware of, I think
it's worth exposing the Payload object and the user to the server in
order to get the correct state on the first render.
And if that's not possible and the request has to be made on the client,
I think initializing the state as collapsed and then expanding it is
better than not showing it at all.
Another observation that is evident from the video, is that there are
several sources or causes of CLS besides the expanded/collapsed state of
the blocks.
- [x] I have read and understand the
[CONTRIBUTING.md](https://github.com/payloadcms/payload/blob/main/CONTRIBUTING.md)
document in this repository.
## Type of change
- [x] Bug fix (non-breaking change which fixes an issue)
## Checklist:
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] Existing test suite passes locally with my changes
- [x] I have made corresponding changes to the documentation
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