The solution isn’t to stuff everything it needs to know into the context, it is to have it write out what it needs to know for every part. It should write out plans, infrastructure decisions, etc, and then use those in future work as needed.

Yea by the time you get to 300k context its IQ is a solid standard deviation lower anyway, why would you really want to beyond that?

Exactly. Just about every prompt I issue these days generates or edits an .md file.