# Implementation Plan

1. Extend the native OSM parse/model with marked crossing-node evidence while
   preserving existing road IDs and parser behavior.
2. Add native crossing clustering, tangent resolution from directed lane
   centerlines, stripe geometry, safe stop-line placement, and source
   diagnostics.
3. Persist the two new layers in `compile-native-roads.js`, comparison counts,
   native build records, required native layer checks, and existing Blender
   material mappings.
4. Add Workbench API/state fields, Chinese layer toggles, selection evidence,
   and summary counts while retaining scene-preview behavior.
5. Add focused fixtures for marked and unmarked crossings, duplicate cluster
   handling, a missing native-lane diagnostic, and output layer contracts.
6. Run native/unit/workbench/build-stage tests, compile/check Nantaizi, then
   build `blender,cesium,preview --road-provider native` without `package/`.

## Validation

```bash
npm run test:native-road
npm run test:road-workbench
npm run test:build-stages
npm run road:compile -- --config config/areas/nantaizi-lake-innovation-valley.json
npm run road:check -- --config config/areas/nantaizi-lake-innovation-valley.json
npm run build:area -- --config config/areas/nantaizi-lake-innovation-valley.json \
  --stages blender,cesium,preview --road-provider native
```

Rollback is selecting `--road-provider osm2streets`; no legacy output path is
changed.