NGD & rendering

Normalized Geometry Document (NGD) is the engine’s consumer-independent output. It contains a canvas, an ordered element list, and explicit paint layers.

flowchart LR
  NGD["NGD"] --> Group["NgdGroup"]
  NGD --> Edge["NgdEdge"]
  NGD --> Node["NgdNode"]
  NGD --> Vector["NgdVector<br/>typed primitives"]
  NGD --> Label["NgdLabel"]

  Group --> Renderer["renderSvg()"]
  Edge --> Renderer
  Node --> Renderer
  Vector --> Renderer
  Label --> Renderer
  Renderer --> SVG["layered SVG"]

Resolved means resolved

NGD carries node rectangles, route points, perimeter anchors, measured text boxes and baselines, group-label chips, decoration primitives, semantic paint roles, and canvas dimensions. It never carries raw SVG or product-specific artwork.

renderSvg() owns only the SVG shell and layer ordering. Element serializers own the documented shape vocabulary. The renderer cannot remeasure, resize, route, or nudge.

Renderer difficulty is an engine contract smell

If a consumer cannot render NGD without inferring geometry, improve NGD and materialization. Do not hide layout logic inside the harness.

Structured decorations

Sequence lifelines, activation bars, rack breaks, and legends use typed path, rectangle, circle, and text primitives. Paints remain semantic tokens until the harness skin resolves them. Their explicit layer decides whether they appear with groups, edges, nodes, or labels.