Track changes in markdown — for humans and AI agents. Collaboration needs a portable interchange format: intent and review history live in the character stream, not in chat logs, PR comments, or proprietary UIs. State lives in the world, whoever holds the file can verify what was proposed, reviewed, and decided without asking a service for a second, hidden source of truth; participation, privacy, and how control can be exercised or resisted all follow from that. *For collaboration, a file form