A last-element lookup over an adaptive list (the node behind AList.tryLast). Registers nothing; the last element is re-read at the next read after a write, and the version advances only when the last element actually changed: an append, a remove of the last element, or an update of the last element. An insert or remove elsewhere shifts positions but leaves the last element untouched, so it bumps nothing. The value is re-read from the source view (O(1)).