Chapter 28: The Closure Sector: Decomposition and Nutrient Return

The closure (recycler) sector is formally defined as the η-fiber restricted to E₂ carriers, with structure recycling as the defining predicate. A carrier satisfies structure recycling when its Loop_L factors through Loop_rec on the η channel, returning existing structure to available form. The central theorem identifies the closure sector as the unique sector on the η-fiber that returns structural complexity to simpler components, with fungi as the biological archetype.