Hybrid Book Cover Melds Two Distinct Visual Styles Seamlessly

WITH
input(a) AS ( VALUES (:INPUT_A) ),
styles(i,name) AS (SELECT row_number() OVER()-1,v FROM unnest(:STYLES) v),
treats(i,name) AS (SELECT row_number() OVER()-1,v FROM unnest(:TREATMENTS) v),
rolls AS ( SELECT s1,s2,t1,t2 FROM seeded_distinct2(styles,treats,seed) ),   -- CHECK (s1<>s2 AND t1<>t2)
fusion AS ( SELECT s1 type_grid, s2 image_mood, t1 surface, t2 edge FROM rolls ),   -- B₁ ownership
cover AS ( SELECT restyle(a, fusion) AS c FROM input, fusion
           -- CHECK ( layout_of(c) = layout_of(a) ) )                              -- B₂ fidelity

SELECT sheet_2to1( at_true_trim(cover.c), spine(a), back_zone(a),
                   finish_macros(t1,t2), light=>raking_specular ) AS asset_sheet
FROM cover, rolls, input
-- B₁: CHECK ( one owner per channel; coherent identity )
-- B₂: CHECK ( title/author bbox = InputA AND trim = InputA )
-- B₃: CHECK ( each treatment's optical signature visible AND physically plausible combo )
-- B₄: CHECK ( genre_fit AND title_dominant AND legible )
-- B₅: CHECK ( aspect(sheet)=(2,1) AND ratio(cover)=ratio(trim) )
-- forbidden rows (stretched / moved title / invisible finish / fighting styles) violate CHECKs
;