Riddle 3 Answer

And it looks like I did it again—Riddle 3 has been lacking an official answer for almost a year!
Ciaran Gorman’s answer was correct—strings with leading and/or trailing space are exactly what I was thinking of, and the serialization technique he showed is how to deal with them.
The following function should work as a general solution:

{0x01,($[.z.o like"s*";reverse;::]0x0 vs"i"$10+count x),0x000000f5,("x"$x),0x00}