The Claude file, documentation, and memories you leave in the project are part of the harness. Most of Claude's forgetfulness can be eliminated with strategic placement of documentation. After you've got that figured out, you'll have to compact the session long before it forgets because it starts getting sloppy and slow at high context. With your guidance it will basically keep its own harness updated for you as the project progresses.

And it also helps to give it better tools than grep and find to explore, because it can waste lots of tokens and pollute the context with the defaults.