Frozen input param

Is it possible to define a parameter on input schema (zod) that will have a hardcoded/frozen value wich should not be changed?
So the value is like predefined in the schema but should be like not accessible via the client to modify?
Or shall I add it in the procedure or something

I guess something like this should work right?

fields: z
    .enum(['addressDetails,format,lifecycle'])
    .default('addressDetails,format,lifecycle'),

literal

Ohh RIGHT! I've missed them somehow... Thanks ❤️