# Implementation Plan

1. Define the native signal model/override artifact and migration adapter;
   reuse existing generation, validation, and deterministic signal UID rules.
2. Add QGIS import/export commands that translate
   `traffic_signal_assemblies.geojson` to/from the native artifact without
   making native compile depend on QGIS.
3. Extend native compile/workbench state to expose signal assemblies, OSM
   controls/arms, and derived runtime provenance.
4. Add validated atomic signal save operations for generate, move, rotate,
   delete, and field edits; preserve legacy ID compatibility.
5. Add Workbench map styling, selection, editing controls, dirty state, save,
   compile/reload, and clear error handling for signal assemblies.
6. Ensure native Blender/Cesium/preview stages consume runtime signal data
   generated from the native model, while legacy stages remain compatible.
7. Add focused traffic-signal, Workbench, migration, and cross-layer round-trip tests;
   run the existing legacy traffic-signal and preview suites.

## Validation

```bash
npm run test:traffic-signals
npm run test:preview-assets
npm run test:road-workbench
npm run road:compile -- --config config/areas/nantaizi-lake-innovation-valley.json
npm run road:check -- --config config/areas/nantaizi-lake-innovation-valley.json
```

Manual acceptance must cover native-only generate/move/rotate/delete -> save ->
recompile -> runtime JSON and preview, plus QGIS import/export compatibility;
disabled signals must be omitted from runtime output.