graft

Graft[Affine] — the build-channel injection vocabulary, reading Affine's arms on its build seam: Miss is the arm where the engine does not call the coalgebra for the slot (an apo graft places the payload by reference; a futu unroll expands a prebuilt layer — "finished"), Hit the keep-going arm (focus alongside its one-layer leftover context). This is the decoration vocabulary the recursion-scheme zoo's build-side citizens (apo's scatter, futu's unroll) construct and consume; the payload meaning of done is pinned per optic value via the existential X (Fst[X]), not here.