Each Claude Code session now gets its own state file at:
~/.claude/buddymon/sessions/<pgrp>.json
Contains: buddymon_id, session_xp, challenge — all session-local.
Global active.json keeps the default buddymon_id for new sessions.
/buddymon assign writes to the session file only, so assigning in one
terminal window doesn't affect other open sessions. Each window can
have its own buddy assigned independently.
SessionStart creates the session file (inheriting global default).
SessionStop reads XP from it, writes to roster, then removes it.
c85bade62f