feat: add native lane separator style overrides

.trellis/tasks/08-17-native-lane-separator-styles/check.jsonl

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+{"_example": "Fill with {\"file\": \"<path>\", \"reason\": \"<why>\"}. Put spec/research files only — no code paths. Run `python3 .trellis/scripts/get_context.py --mode packages` to list available specs. Delete this line once real entries are added."}

.trellis/tasks/08-17-native-lane-separator-styles/design.md

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+# 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.

.trellis/tasks/08-17-native-lane-separator-styles/implement.jsonl

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+{"_example": "Fill with {\"file\": \"<path>\", \"reason\": \"<why>\"}. Put spec/research files only — no code paths. Run `python3 .trellis/scripts/get_context.py --mode packages` to list available specs. Delete this line once real entries are added."}

.trellis/tasks/08-17-native-lane-separator-styles/implement.md

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+# Implementation Plan
+
+1. Validate and resolve per-lane-pair style overrides.
+2. Generate default/dashed/solid style geometry and effective properties.
+3. Add the native Blender yellow lane-separator material route.
+4. Add Workbench selection, Chinese editor and automatic staging.
+5. Test compiler, Workbench, Blender catalog and Nantaizi native build.

.trellis/tasks/08-17-native-lane-separator-styles/prd.md

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+# Native lane separator style overrides
+
+## Goal
+
+Make native same-direction lane separators selectable and persistently editable
+in Road Workbench, using the style override pattern proven for centre lines.
+
+## Confirmed Facts
+
+- `compileLaneMarkings()` writes one continuous `0.12m` Polygon separator
+  between each adjacent lane pair, identified by `road_id`, `left_lane_index`
+  and `right_lane_index`.
+- Lane separators currently have fixed light marking material and are displayed
+  together with turn arrows in Workbench.
+- `native-road-overrides.json` already supports validated, persistent centre
+  line styles by logical native segment. The new type must not alter road-edge,
+  curb or sidewalk geometry.
+
+## Initial Requirements
+
+- Selecting a lane separator must show its lane-pair source and a Chinese
+  style editor.
+- The first style catalog should mirror centre lines: white/yellow and
+  dashed/solid.
+- The effective style must be generated into GeoJSON, visible in Workbench,
+  and consumed by native Blender/Cesium.
+- Default output must remain the current white dashed-style separator.
+
+## Out Of Scope
+
+- Road-edge lines, curbs, sidewalks, double lines, partial ranges, lane-specific
+  legal restrictions and osm2streets layers.
+
+## Key Decision
+
+Each override applies only to the selected adjacent lane pair. This preserves
+separate marking semantics on roads with three or more lanes.
+
+## Acceptance Criteria
+
+- [ ] Selecting a separator exposes a Chinese style editor for its adjacent
+  lane pair; choosing a style stages it automatically.
+- [ ] Save and regeneration preserve the per-pair style across reloads while
+  unedited separators retain the default.
+- [ ] GeoJSON, Workbench, Blender and Cesium show the same effective style.
+- [ ] Tests cover validation, defaults, per-pair isolation, automatic staging
+  and native scene consumption.

.trellis/tasks/08-17-native-lane-separator-styles/task.json

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+{
+  "id": "native-lane-separator-styles",
+  "name": "native-lane-separator-styles",
+  "title": "Native lane separator style overrides",
+  "description": "",
+  "status": "in_progress",
+  "dev_type": null,
+  "scope": null,
+  "package": null,
+  "priority": "P2",
+  "creator": "dingkang",
+  "assignee": "dingkang",
+  "createdAt": "2026-08-17",
+  "completedAt": null,
+  "branch": null,
+  "base_branch": "feature/native-road-compiler",
+  "worktree_path": null,
+  "commit": null,
+  "pr_url": null,
+  "subtasks": [],
+  "children": [],
+  "parent": null,
+  "relatedFiles": [],
+  "notes": "",
+  "meta": {}
+}