Do you think it's impossible for someone to have a 25K line PR / diff but not know what's going on in the system?

I ask because I've pushed some of this to the limit in my own testing and when I get the right building blocks / primitives in place in the repo, I'm able to get plans written in a way where I don't just describe what I want but specifically mention outcomes, verifications, constraints, etc. that utlimately describe the shape of my system and my intent.

My plan is my understanding of my system and the changes I'm making, and the execution of that plan (e.g. with subagents), verified against my spec, is the code itself.

With the correct building blocks, I've found that frontier models can write code in fairly predictable ways that lets me maintain my understanding and confidence in pretty large PRs.

I think perhaps the quoted part of your post seems to imply it's not possible / isn't phrased with that nuance?