Adding a new session (a role)

Part 4 · A SESSION, SCHEMATICALLY · Slide 56 of 60

There is no role variable. A role is set BY PROMPT:
"You are the DIRECTOR for <project>" as the first message,
or a lane's commission text — which agent-ledger banks to
briefs/ verbatim, so the role is auditable afterwards.

   owner ──► prompt names the role ──► session binds its scope
   director ──► commission (contract + touch-only + done-when)
            ──► builder lane ──► return ──► director gates

For a multi-session arrangement: new-fable-project.sh seeds one
blackboard per lane; fable-director runs them.