# OpenSpec Change: enterprise-gaming-bone-mapping

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

---

## Summary

Deliver `@suaveplan/bone-mapping` on the genesis branch from scratch at enterprise quality. The package provides skeleton detection, bone matching by fuzzy name heuristics, and retargeting math — the foundation for animation clip transfer between different character rigs. `detectSkeleton` classifies a bone hierarchy as Mixamo/Humanoid/Custom; `matchBones` pairs source and target bones using edit-distance scoring with anatomical weight boosts; `retargetPose` transforms local-space bone rotations from source binding pose to target binding pose using the standard retargeting matrix `R_target = T_offset * R_source * T_offset^-1`. Genesis adds Zod schemas, structured errors, and property-based correctness tests.

---

## Current-state audit (genesis)

Package does not exist on genesis yet — fresh build.

---

## Available workspace deps on genesis

| Package | Role |
|---|---|
| `@suaveplan/error` (`workspace:^`) | `BoneMappingError`; `BONE_MAP.*` codes |
| `@suaveplan/types` (`workspace:^`) | Shared primitives |
| `zod` (`catalog:forms`) | Bone map result schemas |
| `@opentelemetry/api` (`catalog:observability`) | Detection + match spans |

---

## Public API surface

```ts
type SkeletonType = 'mixamo' | 'humanoid' | 'custom'

function detectSkeleton(bones: BoneDescriptor[]): SkeletonType

function matchBones(
  source: BoneDescriptor[],
  target: BoneDescriptor[],
  options?: MatchOptions
): BoneMatch[]

interface MatchOptions {
  minConfidence?: number     // 0–1, default 0.5
  preferExact?: boolean
}

interface BoneMatch {
  sourceBone: string
  targetBone: string
  confidence: number
}

function retargetPose(
  sourcePose: BonePose[],
  boneMatches: BoneMatch[],
  sourceBindPose: BonePose[],
  targetBindPose: BonePose[]
): BonePose[]

function buildRetargetMatrix(
  sourceBind: Quat,
  targetBind: Quat
): RetargetMatrix

interface RetargetMatrix {
  apply(rotation: Quat): Quat
}

interface BoneDescriptor {
  name: string
  parentIndex: number
  localPosition: Vec3
  localRotation: Quat
}

interface BonePose {
  boneIndex: number
  position: Vec3
  rotation: Quat
}
```

### Error codes

```ts
type BoneMapErrorCode =
  | 'BONE_MAP_NO_BONES'
  | 'BONE_MAP_MATCH_FAILED'
  | 'BONE_MAP_RETARGET_FAILED'
  | 'BONE_MAP_INVALID_BIND_POSE'
```

---

## New additions for genesis

1. **Fuzzy bone matching** — Levenshtein distance + anatomical keyword boosts (`spine`, `arm`, `leg`, `hand`, `foot`).
2. **Humanoid auto-detect** — classify skeleton as Humanoid if ≥ 60% of canonical human bone names match within edit distance 2.
3. **Retarget matrix** — `R_target = T_offset * R_source * T_offset^-1` where `T_offset = target_bind * inverse(source_bind)`.

---

## File layout

```text
gaming/rigs/bone-mapping/
  package.json
  tsconfig.json
  vitest.config.ts
  src/
    index.ts
    error-codes.ts
    constants/index.ts
    types/common.ts
    types/common.md
    core/
      detect/
        detect.ts
        detect.md
        detect.test.ts
        index.ts
      match/
        match.ts
        match.md
        match.test.ts
        index.ts
      retarget/
        retarget.ts
        retarget.md
        retarget.types.ts
        retarget.test.ts
        index.ts
    utils/
      quat-math.ts
      quat-math.md
      quat-math.test.ts
  tests/
    property.test.ts
```

---

## Impact

**Downstream**: `@suaveplan/mixamo` imports `detectSkeleton` and `retargetPose`; `@suaveplan/ik-solver` uses quaternion math from utils. Prerequisites: `@suaveplan/error`, `@suaveplan/types`.