Function nova_rt_bytes_is_utf8 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn nova_rt_bytes_is_utf8(
    b: *const NovaStr,
) -> i8

Whether b’s bytes are valid UTF-8.

Paired with nova_rt_bytes_to_string_unchecked so std/bytes’s to_string can be a Nova-level if, rather than needing a status-code protocol for what is one boolean.

Safety

b must point to a live NovaStr.