Function compute_notification_gates 

fn compute_notification_gates<F: Fn(u64) -> bool>(
    _: GateInputs<'_>,
    in_window: F,
) -> NotificationGates<impl Fn(&UInt) -> bool + use<F>>

The gates deciding what notification counts a joined room reports.

A count reaches the client when the round carried timeline events or a read cursor advanced within the window. An explicit zero additionally needs a cursor newer than the request token, and because the response cutoff is captured before that cursor is read, a cursor past the cutoff repeats the zero until the token catches up.