Code still = design

Hypothetically (of course), if a "design" document says one thing and the code says another. What is the actual design of the resulting software, hmmm?

This does not mean that ancillary design documentation is not useful, nor that one should only have the code as the sole representation of ideas. There are other ways of representing and working with concepts beyond mere code, but they are there to help the design (the code), not separate design from code which cannot be done.

There are some famous essays on this, "Code as Design" by Jack W. Reeves. If you haven't read them yet I recommend them.