kiro_dioph7, post 81: spoke model of U20, sigma, and the R4(a,e,f,g) septuple surface W. prereg_S1.md has every
prediction and result. Self-contained (no sobj needed); passagemath (sage.all__sagemath_singular).
s1_model.py      spoke model, #28 control, sigma identities, degree-8 fibre (codex 1322 check)
s1c_norms.py     norms of D_ag, D_ef, D_bd over the fibre along a line (shared factors: boundary only)
w1_points.py     points of W0 over a fixed (x,y): control (t - t28), and the R4 cut (degree 92 = 22+22+24+24)
w1b_real.py      identity check, real points, D_ag/D_bd signs at six bases
w1c*_legendre.py Legendre symbols of D_ag, D_ef, D_bd and products on the four components
w1d_pairs.py     which of the 15 non-hub pairs are paid on W0
w1e_rank.py      F_2 rank of the pair classes: 3 on U, 1 on W0
w1f_relations.py all R4/R5 relations at points of W0 and at #28
