A face of degree 1 in one direction (an extruded spline) was refused with "a fairness term does
not fit the net's degrees": the thin-plate energy's S_vv asks for second derivatives a linear
direction does not have. On every span that term is exactly zero, so it is dropped; the energy is
the bending along the curve and the twist. A face whose held layers are its whole net (a
single-span cubic with its edges kept, an extruded curve's two rows) has no interior control
point: it is left exactly as it is, its energy reported unchanged, 0 steps.
cov-fair-single-span-face-has-nothing-free-to-move passes and leaves KNOWN_FAILING.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
jyvikoandClaude Opus 5.5
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