Zod v4 internationalization

[fr33bits]

I have been unable to get Zod error messages in a language other than English to show up in Superforms. In v4 Zod has added native internationalization support however it seems that setting the locale for Zod does not set it for Superforms as well. Or maybe it is supported and I just have not been able to get it working? 🤷

Ideally Superforms would get the error message locale from the general Zod config or, optionally, allow the user to select a locale through a function parameter for instance.

That said, the native Zod implementation is also flawed in that it only allows the setting of the locale globally and not on the level of each parse. zod-i18n-map also doesn't support Zod v4 yet and there hasn't really been any activity for a year and a half.

[fr33bits]

For anyone else wondering, I figured out a solution:

As explained here, Zod supports per-parse localization by passing a localized error map to the parse function.

I had trouble figuring out how to achieve the same in Superforms until I looked at the (undocumented?) options of the Zod adapters and realized they do allow you to pass the error map in there as well.

export const serviceInsertAdapter = zod4(serviceInsertSchema, { error: getLocalizedZodErrors() });

It works well even with custom error messages that I didn't set in an error map but rather directly in the schema definition using Paraglide JS.

That said, it would be welcome if this was documented.