Module fragment 

Laid-out geometry queries — hit-testing, box-model lookup, anchor-to-fragments, selection rects.

Cf. Hekate doc §“Layout/Fragment Plane”. The trait is the permanent ABI; internal plane storage (IndexVec / FxHashMap / whatever) stays each lane’s implementation detail.

Structs

BoxModel

CSS box-model for one source node’s fragment. The four nested rectangles — content / padding / border / margin — are each in viewport coordinates. Consumers wanting getBoundingClientRect shape read border (the border-edge rect).

FragmentHit

What hit_test returns. Carries the lane’s fragment id, the containing source node, and the local hit point inside the fragment (so consumers can drive caret positioning without re-walking).

Traits

FragmentQuery

Common-minimum laid-out-geometry queries. Each lane that has a layout phase implements this. Internal FragmentId type is per- lane (opaque to consumers — only used as a map key).