Zod's `z.stringbool()` not accepted on true/false input fields

[fr33bits]

My app uses true/false "boolean" string values (where only true/false should be accepted) as hidden fields in several forms (that just look like buttons to the user) which are used to toggle roles for a particular user. Each such form has two hidden fields — the name of the role and whether or not the user had it when the page was loaded (to prevent unexpected toggles when the role has already been added/removed server side after page load) — as well as a submit button that indicates the role being toggled.

I want to use z.stringbool(), introduced in Zod v4, which is a convenient way to parse a string and convert it to a boolean while ensuring only certain values are accepted as truthy or falsy. In my case:

z.stringbool({
	truthy: ['true'],
	falsy: ['false'],
	case: 'sensitive'
});

Unfortunately using z.stringbool() as part of the schema that then gets passed to Superforms causes an issue because, as I understand it, Superforms detects that this is supposed to be a boolean type and thus uses its own parsing logic whereby all non-"false" values by default evaluate to true and Superforms passes an actual boolean value (not a string) to Zod, which results in the error Invalid input: expected string, received boolean when parsing the submitted form data.

• This is not a desired outcome as validation using z.stringbool() should be successful when the input is set to "true" or "false" and fail otherwise
• While using z.boolean() or z.coerce.boolean() will not fail validation when true/false are used, it will also not fail if non-true/false values are used as once again all non-"false" values will evaluate to true.
• The only way the desired behavior can be achieved is using z.enum(['true', 'false']).transform((value) => value === 'true'); however I would rather avoid this workaround as it is non-standard and not used throughout the rest of the project

MRE: https://www.sveltelab.dev/1qopi89nlzl9n8n

[ciscoheat]

There is no apparent way to distinguish a boolean from a stringbool in the JSON Schema override, so if you can post an issue and ask if that's possible at the Zod repo, then we can proceed. Relevant code:

toJSONSchema(schema, {
  unrepresentable: 'any',
  override: (ctx) => {
    // How to distinguish between z.boolean and z.stringbool here?
  }
});

[fr33bits]

Ah, I was away for a while but I see you've already created a Zod issue, awesome. Thanks!