{
  "type": "object",
  "additionalProperties": false,
  "required": ["schema_version", "coordinate_space", "parts", "notes"],
  "properties": {
    "schema_version": {"type": "integer", "enum": [2]},
    "coordinate_space": {"type": "string", "enum": ["normalized_xy_top_left"]},
    "notes": {"type": "array", "items": {"type": "string"}},
    "parts": {
      "type": "array", "minItems": 1, "maxItems": 64,
      "items": {
        "type": "object", "additionalProperties": false,
        "required": ["id", "semantic", "parent", "rig_role", "bind_to", "completion", "visibility", "bbox_norm_xyxy", "pivot_norm", "positive_points_norm", "negative_points_norm", "occluded_by", "needs_completion", "confidence"],
        "properties": {
          "id": {"type": "string", "pattern": "^[a-z][a-z0-9_-]*$", "maxLength": 64},
          "semantic": {"type": "string", "minLength": 1},
          "parent": {"type": ["string", "null"]},
          "rig_role": {"type": "string", "enum": ["bone_part", "attachment", "facial_feature"]},
          "bind_to": {"type": ["string", "null"], "description": "bone_part: null; attachment/facial_feature: existing bone_part ID or null for root"},
          "completion": {
            "type": "object", "additionalProperties": false,
            "required": ["occlusion_fill", "joint_extension_parent", "joint_extension_child"],
            "properties": {
              "occlusion_fill": {"type": "boolean"},
              "joint_extension_parent": {"type": "boolean"},
              "joint_extension_child": {"type": "boolean"}
            }
          },
          "visibility": {"type": "string", "enum": ["visible", "partial", "hidden"]},
          "bbox_norm_xyxy": {"type": ["array", "null"], "minItems": 4, "maxItems": 4, "items": {"type": "number", "minimum": 0, "maximum": 1}},
          "pivot_norm": {"type": "array", "minItems": 2, "maxItems": 2, "items": {"type": "number", "minimum": 0, "maximum": 1}},
          "positive_points_norm": {"type": "array", "maxItems": 32, "items": {"type": "array", "minItems": 2, "maxItems": 2, "items": {"type": "number", "minimum": 0, "maximum": 1}}},
          "negative_points_norm": {"type": "array", "maxItems": 32, "items": {"type": "array", "minItems": 2, "maxItems": 2, "items": {"type": "number", "minimum": 0, "maximum": 1}}},
          "occluded_by": {"type": "array", "items": {"type": "string"}},
          "needs_completion": {"type": "boolean"},
          "confidence": {"type": "number", "minimum": 0, "maximum": 1}
        }
      }
    }
  }
}