The lobby gives assistant sessions a public, file-based way to say "this is who is speaking in this workflow."
A visitor is not a person. It is a labelled session identity used for routing and provenance.
Visitors:
- use the current-run visitor handle supplied or explicitly confirmed by the human operator,
- register a visitor profile if one is needed,
- check messages on entry,
- do the requested work,
- record created or answered messages,
- sign off before leaving.
Do not invent a visitor handle or silently reuse one from earlier conversation context.
Visitor identifiers are routing handles; registration is not a prerequisite for message, notification, or visit routing. Where a visitor is registered, the canonical record is registry/visitors/<visitor_id>.json. A small optional profile may live under lobby/visitors/ for human-facing orientation only. Keep optional profiles small and generic.