Status: IN
Chain of Responsibility's structural reliability when following Composite parent references (tree root guarantees chain terminus, existing links eliminate explicit construction) combined with NullIterator's completion of recursive traversal (eliminating special-case leaf handling) yields fully engineered recursive infrastructure: traversal is uniform top-to-bottom via NullIterator, and request routing is reliable bottom-to-top via Composite-backed chains — bidirectional recursive processing without special cases.
NullIterator completes downward traversal, Chain-Composite completes upward routing — bidirectional recursive completeness
Depends on (SL): chain-composite-structural-reliability, null-iterator-completes-recursive-traversal