Root cause: typed segment offsetting created self-intersecting geometry at
concave corners (notches). Triangle's PSLG boundary didn't match the plotted
inset contour, allowing vertices 7+ mm outside.
Changes:
- _build_inner_plate: always use Shapely buffer(-w_frame) (robust at concavities)
- _sample_ring: use simplified polygon vertices + interpolated points on long edges
(preserves tight features without vertex clustering)
- Plot uses same inner_plate from triangulation (no mismatch)
- Post-process: snap any residual outside vertices to boundary
- Result: 0 vertices outside inner plate (was 10, up to 7.45mm)
Antoine
78f56a68b0