Extension metadata tokens

This example illustrates how $extensions carry vendor metadata alongside component slots, motion tokens, and responsive dimensions. It shows accessibility annotations and custom intent flags traveling with the base values.

See extensions.tokens.json for the complete document.

Sample tokens

{
  "$version": "1.0.0",
  "color": {
    "cta": {
      "$type": "color",
      "$value": {
        "colorSpace": "srgb",
        "components": [0, 0.5, 1]
      },
      "$extensions": {
        "org.example.ai": {
          "intent": "primary action"
        }
      }
    },
    "link": {
      "$type": "color",
      "$value": {
        "colorSpace": "srgb",
        "components": [0, 0, 1]
      },
      "$extensions": {
        "org.example.a11y": {
          "wcagContrast": 4.5
        }
      }
    }
  },
  "motion": {
    "fade": {
      "$type": "duration",
      "$value": {
        "durationType": "css.transition-duration",
        "value": 200,
        "unit": "ms"
      },
      "$extensions": {
        "org.example.a11y": {
          "prefers-reduced-motion": true
        }
      }
    }
  },
  "spacing": {
    "responsive": {
      "$type": "dimension",
      "$value": {
        "fn": "clamp",
        "parameters": [
          {
            "dimensionType": "length",
            "value": 8,
            "unit": "px"
          },
          {
            "dimensionType": "length",
            "value": 2,
            "unit": "vw"
          },
          {
            "dimensionType": "length",
            "value": 16,
            "unit": "px"
          }
        ]
      }
    }
  }
}