Thinkmill
First-party multilingual support for Keystatic
There are a lot of requests for a first-party support for multi-language sites with Keystatic.
Particularly when used with Astro, which supports i18n out of the box.
I think there is enough interest/demand to consider investigating a proper multi-language support solution for Keystatic, if time allows 😇
I think the implementation in Decap CMS is quite clear (https://decapcms.org/docs/i18n). An additional "copy" feature would also be helpful (https://github.com/sveltia/sveltia-cms/issues/120).
For the UI, I believe a simple select option would probably work best, without the need for side-by-side editing.
For validation, perhaps if there is an error in a language other than the one I am viewing, when I save, it could switch to the language with the validation error and scroll to the problematic field.
In my case, the most important part of this integration is just the authoring experience. I would love to not have the language part of the slug in the list, and of course not have duplicates in that list, but instead have them in the same "page" (with a way to switch between languages like @zanhk suggested).
Of course other people will have other needs!
It could also be useful to en-/disable i18n on a per-collection/singleton basis, since there might be cases where only certain pages need translation.
Another thing that might be worth mentioning are localized images. From working with Hygraph I've come to like the option of providing two versions per image. This could, of course, also be disabled per image!
