docs(#860): direct A2A replies, the TCK's DM-MSG-001, retention.a2aMessages; #900 a decision holds no file descriptor Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_012Kh8JktXfvKCu6FsQzPzcC
feat-810: A2A — the mesh on the listener, charges once across passes, the two extension pages