One rail per baked taste cluster or borrowed theme, each with the title written offline, plus the cta that owns the board's first slot.

Self-serving, same access as the other recs reads: a user reads their OWN clusters. A guest has none baked, so they get empty rails rather than a 401.

as_user impersonation stays an admin-preview affordance on BOTH ends — the requester must be an admin and the target must itself be an admin account. A taste rail is derived from that person's saved places and its title names their tastes, so it is not a projection an admin may read for anyone else. preview_state takes the same admin guard on the requester, and is logged as a preview for the same reason.

Empty rails is the normal answer for a user with nothing baked and no themes to borrow.