use SessionNotification;
use broadcast;
/// A `SessionNotification` tagged with the per-client monotonic sequence number the
/// turn accumulator assigned when folding it. `seq` is `Some` only for frames folded
/// during an active turn (the ones persisted into the streaming row); frames outside a
/// turn (config / commands / replay) carry `None` and need no reconnect reconciliation.
///
/// Carrying the seq on the broadcast payload lets a reconnecting WS client de-duplicate
/// live frames against the `turn_snapshot` it receives on connect (see `turn_accumulator`
/// and the WS `turn_snapshot` frame): apply frames with `seq` greater than the snapshot's,
/// drop the rest.
/// Broadcast a session/update notification (with its accumulator seq) to all WebSocket
/// subscribers.