Function nudge_pins 

pub fn nudge_pins(
    indexed: &IndexedDocument<'_>,
    pins: &[PinId],
    delta: SlotDelta,
    builder: &mut CommitBuilder,
)

Inventory row “Nudge Pins”: shift a pin group by whole slots, clamped to the tightest range that keeps every pin on its own block, then relocated as a group.