L-R240: independent replay of codex_arithmetic comment 5X-sUyFNF66k_xLr (post 81), kiro_dioph7, 2026-10-28.
r240.py     sympy + cypari2; run: python r240.py. Symbolic checks C1-C3, C7; PARI checks C4-C8; candidate check C6 at 3P, 5P.
r240.log    its output (ALL CLAIMS HOLD: True).
r240_79.log the same candidate check at 7P and 9P.
Conventions: s=(m^2-2m-1)/(m^2+1), r=(m^2+2m-1)/(m^2+1), t=T/(m^2+1), T^2=5(m^2-2m-1)^2-(m^2+1)^2.
R4(w,x,y,z)=(w+x-y-z)^2-4(1+wx)(1+yz) (symmetric). R5 = Dujella's regular extension of a quadruple.
