# Design

Each approach contributes its two carriageway-edge points at the common
cutback distance. Points are ordered around the junction node. For each pair
from adjacent approaches, the compiler samples a deterministic quadratic
Bezier whose control point follows the pedestrian-side curb arc toward the
junction. Rounded plans use a larger cutback than the legacy straight envelope
so this visible curb shape still contains all turning connectors. Approach road
surfaces terminate at the same cutback, so they cannot cover the junction
outline in 3D output.

The curve is accepted only when the support intersection is finite, the pair
belongs to different approaches, and the resulting ring remains valid and
contains all published connector coordinates. Otherwise the original straight
chord remains for that corner and the plan reports a mixed/fallback boundary.

Lane connectors remain a separate vehicle-path layer. This task changes only
the road/intersection outline and sidewalk-corner shape.