I have found that claude (opus 4.8 and 5) can do a very good job of implementing good architecture and system design if I can just steer it right. left to its own devices it does produce less than optimal code, but if I just spend a few minutes explaining how some pattern will improve the code, claude will go do it the right way, and can even have a pretty sensible discussion about the tradeoffs involved. so it does know about good code architecture and patterns, it just doesn't have the taste and initiative to use them without being told.