# Implementation Plan

1. Add centre-dash constants and a pure native compiler routine based on the
   shared bidirectional segment model and junction-trimmed centreline.
2. Filter invalid, one-way, service, and control-marking-conflicting dashes;
   record actionable diagnostics for invalid geometry only.
3. Write `center_lines.geojson`, compilation/comparison counts, native build
   records, required-layer checks, and Blender material adapter mapping.
4. Add Workbench API state, Chinese toggle, summary count, rendering, and
   source evidence for a selected centre dash.
5. Add focused native and Workbench tests for generation, skips, control
   avoidance, provenance, and file/API contracts.
6. Run native/unit/workbench/build-stage tests, compile/check Nantaizi, then
   validate `blender,cesium,preview --road-provider native` without `package`.

## Rollback

Choose `--road-provider osm2streets`; no legacy layer or published package is
modified.