isDegenerateApexCorner measured the inner-face convergence as
max(h1,h2)/tan(theta/2) — for a 10-degree apex between a 15 cm and a 30 cm
wall that overstates the distance (171.5 cm against the true 128.3/128.9 on
160 cm edges), the corner failed the "inside both edges" test and rendered
as the #329 trident again. Worse, the verdict depended on which neighbouring
edge carried the thicker wall.
The check now intersects the two actual face lines: the meeting point lands
at (hOther + hOwn*cos(theta))/sin(theta) along each edge, degenerate only
when inside both. With equal halves this reduces algebraically to the old
h/tan(theta/2), so equal-thickness verdicts are unchanged by construction —
pinned by the untouched section-4 units and the full golden matrix (136
scenes verified). New units cover both traversal orders of the mixed apex,
the one-point outset tip, the 30-degree ordinary pair and the zero-thickness
guard.
The write path is untouched: P1 forbids new sub-15-degree corners since
issue 329, this is purely how a legacy document renders.
Issue: #339
User-Visible: yes
