The problem I have is that when you squash the code it does the same thing.

  PR.patch = a.patch | b.patch
  exec(PR.patch) = exec(a.patch | b.patch)

When you squash the spec you potentially do not get the same thing:

  PR.md = a.md | b.md
  ai(PR.md) != ai(a.md) | ai(b.md)