# Native Lane Separator Style Overrides Design

## Contract

The override is identified by the stable `roadId` plus the adjacent lane pair:

```json
{
  "id": "车道分隔线:road:way/123:forward:1-2",
  "kind": "lane-separator-style",
  "roadId": "road:way/123:forward",
  "leftLaneIndex": 1,
  "rightLaneIndex": 2,
  "color": "white",
  "pattern": "dashed"
}
```

The same `yellow|white` and `dashed|solid` enums are reused. A default is
white dashed. The generated Polygon stores `color`, `pattern` and
`effective_style`; source IDs remain unchanged.

## Rendering

The existing lane separator polygon represents the whole lane-pair path.
`solid` retains it as one continuous feature. `dashed` samples regular dash
polygons along the shared centreline with deterministic spacing and preserves
junction cutback. White uses the existing `lane_separators` material; yellow
uses a native-only yellow material route. Workbench separates lane separators
from turn arrows so their styles remain selectable and visible.

## Compatibility

No override means current visual default. Road edges, curbs and centre lines
are untouched. Existing `native-road-overrides/v1` files remain valid.