z.coerce takes in unknowns at runtime to output Tanstack expected types zod + nextjs ssr + tanstack

[iSpeakNerd]

Tanstack form passes the data to the server as strings so I'm using z.coerce.number() to handle the conversion but the ts compiler complains about it because zod 4 reads all coerced inputs as unknowns and only outputs the correct types at runtime.

I found this https://tanstack.com/form/latest/docs/framework/react/guides/debugging#field-value-is-of-type-unknown but it's almost the inverse issue because I have Type 'unknown' is not assignable to type 'number'.

I can //@ts-ignore the error but that's on the useForm({}) functio signature so I lose the safety on all other fields as well by doing that. Is there anything I can easily do to mitigate this issue?

I was looking through the example and here's my setup.

zodSchema

const audioSubmissionSchema = z.object({
  url: z.string().url({ message: "Must be a valid url" }),
  description: z
    .string()
    .max(1024, { message: "Must be less than 1024 characters" }),
  name: z.string().max(64, { message: "Must be less than 64 characters" }),
  skip_minutes: z.coerce
    .number()
    .min(0, "Skip must be 0 minutes or more")
    .max(60, "Skip must be 60 minutes or less"),
});

serverValidation.ts

const serverValidate = createServerValidate({
  ...audioFormOpts,
  onServerValidate: async ({ value }) => audioSubmissionSchema.parseAsync(value)

serverAction.ts

export async function submitUrlActionT(prev: unknown, formData: FormData) {
  try {
    const validated = await serverValidate(formData);
    // app logic
    // ...
    // success
    return undefined;
  } catch (e) {
    // validation errors
    if (e instanceof ServerValidateError) {
      return e.formState;
    } else {
      // app logic errors
      throw e;
    }
  }
}