> I haven't managed to really figure out what's the best way

For you, the best way is to break your code down into modules insofar as possible, so that you don't overrun the context window. Opus Max starts forgetting things the minute it begins compressing your conversation -- and multiple compressions can make for gaps in memory.

I find that it's also important to have another model serve as review/critique. I use Opus Max for code and 5.5 Pro for immediate code review. The latter will often pick up on things that might have been missed, and will usually provide good suggestions.