session/{id}/agent/{aid}/plan → ollie-9p write
session/$OLLIE_SESSION_ID/agent/$OLLIE_UNAME/plan
UNAME is the agent's immutable ID, matching the agent directory
name. Using ollie-9p write instead of a mounted filesystem path.
plan now lives at session/{id}/agent/{aid}/plan instead of
session/{id}/plan. Moved the Leaf declaration from fs/sessionfiles.go
to fs/agentfiles.go. Updated both prompt docs to match.
Ollie Agent