I have three repos that all want the same TODO hygiene rules. The first one got them after a review where I caught a TODO: fix this with no owner. The second one picked them up by copying CLAUDE.md from the first. The third one is where I noticed I was opening the second project's CLAUDE.md to copy it a third time.
That is the exact failure Level 3 is supposed to prevent.
The taxonomy is easy enough to write down. Level 2 is the project harness; Level 3 is the organization harness. The hard part is the split inside the repo. If both kinds of rule end up in the same files, the boundary collapses every time someone edits anything. Keystone draws the line in the file tree itself.
The split Keystone draws
A Keystone harness has two halves.
