Function sioul_appnotes_decide 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn sioul_appnotes_decide(
    json: *const c_char,
) -> *mut c_char

decide, for Java (android/main.cpp); a panic answers “null”, and the notification comes as it was sent. Given back to sioul_string_free.

Safety

json is null, or a zero-terminated text valid for the call.