Update to React 19

[tulios]

Hi, first of all, thanks for this project. It was amazing to have the same idea and find it beautifully written here 😄

I am really interested in the RN version. I am currently working on some prototypes where I am trying different techs for an upcoming project, and lightning is one of them. Given my experience with past updates, I like to keep up-to-date with RN, so we are already using React 19 over here.

How willing are you to update to React 19?

I already have a local fork working with React 19 and RN 0.79.3, but it's better to ask in case you already have plans or have a specific opinion on how to do it.

I would love to contribute, but I will wait for your input before any PRs.
Thanks.

[WillsonHaw]

We're currently using the RN stuff internally, and our project is still on React 18, so unfortunately we cannot update on our side yet until we can update all our packages. If you'd like, we can create a React 19 branch. It'd be some extra maintenance required to keep it up to date with all the changes we make here though.

[tulios]

I imagined that this would be the case. What about supporting both reconcilers? It seems that it works for react-pdf, so perhaps it's also an option here. The bulk of the changes are in the Reconciler code, everything else is basically bumped versions and minor type changes (TS definitions on R19 are a bit more strict, but they would work on R18 as well).

I am also open in maintaining the react-19 branch, I don't think the changes would conflict that much. Right now, I am using my fork, but I would rather put that effort into keeping the code in the mainline repo.

[WillsonHaw]

Yeah, I have a similar branch already for React 19 that I've never merged, so I'm kind of aware of the changes needed. I actually also have a React 19 branch with the reconciler changes that I never merged, because of the fixes required in our main app. Even if our team goes React 19 now, I think there's still value to having React 18 support, so I'm not opposed to going the route of something like having two separate entry points so that we could support both cases, rather than a separate branch.