# OpenSpec Change: enterprise-gaming-r3f-terrain

- **Change ID**: enterprise-gaming-r3f-terrain
- **Package**: `@suaveplan/r3f-terrain`
- **Category**: gaming/scene
- **Target path**: `gaming/scene/r3f-terrain`
- **Status**: PROPOSED
- **Date**: 2026-04-24
- **Reference spec**: `/mnt/s/web/suaveplan/enterprise/r3f-terrain.md`

---

## Summary

Deliver `@suaveplan/r3f-terrain` on the genesis branch from scratch at enterprise quality. The package provides procedural terrain with chunked LOD for React Three Fiber. A `TerrainSystem` divides world space into equal-size chunks; each chunk generates a height-mapped `PlaneGeometry` using a pluggable noise function (simplex, perlin, or caller-supplied); LOD is managed by camera distance — near chunks use high subdivision, far chunks use low. Biome tinting (grass/rock/snow) is applied via vertex color or shader. Genesis adds Zod chunk config schemas, structured errors, OTel chunk-load histogram, and 100% coverage.

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## Available workspace deps

`@suaveplan/error`, `@suaveplan/types`, `@suaveplan/events`, `@suaveplan/spatial-hash`, react, `@react-three/fiber`, `@react-three/drei`, three.

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## Public API surface (key exports)

```ts
function Terrain(props: TerrainProps): JSX.Element
// - chunkSize, worldSize, maxLOD, heightScale, noiseFn, biomeMap

function useTerrainHeight(x: number, z: number): number   // sample height at world position
```

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## File layout

```text
gaming/scene/r3f-terrain/
  package.json / tsconfig.json / vitest.config.ts
  src/
    index.ts
    error-codes.ts
    constants/index.ts
    types/common.ts + md
    core/
      terrain-system/ (ts + md + types + test + index)
      chunk-manager/ (ts + md + types + test + index)
      lod-controller/ (ts + md + types + test + index)
    components/
      Terrain/ (tsx + md + test + stories + index)
      TerrainChunk/ (tsx + md + test + stories + index)
    utils/
      noise.ts + md + test
      height-sample.ts + md + test
  tests/integration.test.ts
```