I got this console error when trying your changes on tuono-tutorial. Do you have the same?

I checked tuono-app and tuono-tutorial by putting react and react-dom at v19.0.0

The error Valerio encountered is caused by changing react@19 only on examples/tuono-app package.
However when printing the React version from examples/tuono-app/src/routes/__root.tsx the results is that the actual loaded react version is 18.3.1 not 19:

(The object logs are the children printed inside RootRoute component)

Why this happen?

It happens due to the fact that examples reference `tuono` folder within the repository which contains his own version of `React`. I added a screenshot inside this `details` to show this.

To use the right version of React the right command is:

pnpm --filter="./examples/*" --filter="./packages/*" up react@latest react-dom@latest @types/react@latest @types/react-dom@latest

This should ensure that same version of React is used across all involved packages.

Now it works right?

Unfortunately, no:
when running tuono dev from examples/tuono-app the result is a React minified error printed in the HTML page:

Error: Minified React error #31; visit https://reactjs.org/docs/error-decoder.html?invariant=31&args[]=object%20with%20keys%20%7B%24%24typeof%2C%20type%2C%20key%2C%20ref%2C%20props%7D for the full message or use the non-minified dev environment for full errors and additional helpful warnings.

The links leads here

The error is the same we saw earlier:

Objects are not valid as a React child (found: object with keys {$$typeof, type, key, ref, props}). If you meant to render a collection of children, use an array instead.

But now is printed directly in the HTML page.

What to do next?

I think this PR can be safely merged (after pnpm-lock.yaml changes are reverted).
It should not have impact on react@18, which doesn't use MessageChannel API,
hence this polypill won't be included in the bundle.

Then we can figure out the next steps to support react@19.

WDYT?

Sounds perfect! Thanks for it.