Hi,
Here is a patch to specify the compatible element-type for utf-8 external-format.
For LispWorks the element-type should apparently be 'lw:simple-char. On all other lisps which support utf-8, the type is apparently supposed to be 'character (as it was hardcoded previously in agent/proc-common.lisp).
Note that asdf does something a bit more sophisticated regarding this - they do something with a character-type hierarchy including base-char, #+lispworks lw:simple-char, and character. I'm not sure if we need to get so sophisticated for agent/proc-common.lisp.
Best Regards,
Dave Cooper