Function collect_registered_ticks 

fn collect_registered_ticks<T: TickKey>(
    due_containers: Vec<ActiveTickContainer>,
    select: fn(&mut ChunkTickLists) -> &mut TickList<T>,
    current_tick: i64,
    max_ticks: usize,
) -> (ScheduledTickBatch<T>, Vec<TickHeadUpdate>)

Selects at most max_ticks ready entries from sparse live-container heads.

Only queue heads compete globally. Revealing the next head after each pop is what preserves Vanilla’s per-chunk deadline ordering when several ticks are already overdue.