Sessions
Where each session left off, one file each: YYYY-MM-DD-<n>-slug.md (<n> orders several on one day).
History; what's next is in next-session.md. Practice: session handoff.
At the end of a session, git mv docs/next-session.md here, named for the session it describes,
then write a new next-session.md: only where things stand now, short, linking here for anything older.