Constant SCOPE_SESSIONS_TABLE 

pub const SCOPE_SESSIONS_TABLE: &'static str;

The §4.1 occupancy table (RINDLE-REALTIME-QUERY-ENABLEMENT-DESIGN.md): one row per (scope, session), upserted by the api-server on every labeled lease mint/renewal and aged out lazily by expires_at (mark/refresh/age-out — lease expiry needs no hook anywhere). The row delta IS the upgrade doorbell: a solo client’s only live connection is its daemon subscription, so the 1→2 wake signal must materialize as a row in the store it is subscribed to — which is why Db::enable_realtime_lifecycle registers this table rather than just creating it.