> It's been really frustrating that neither Codex nor Opus can make targetted edits to Fable's code without screwing something subtle up.
Reminds me of the old adage: don't try to be too smart when writing code. Otherwise, dumber people - including your future self - will have trouble working with it.
For reference:
if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it
Some problems are very hard to solve with stupid code. This can easily be the case (computational geometry)