Design Tokens Expert

Expert guidance for working with design tokens following the Design Tokens Community Group (DTCG) specification.

Quick Reference

Getting Started: See Getting Started Guides for step-by-step workflows.

Specification Sources

Based on the latest DTCG Draft Community Group Reports:

• Format Module
• Color Module
• Resolver Module

Core Concepts

Token Structure

A token is a JSON object with $value. Special properties use $ prefix:

{
  "brand-blue": {
    "$type": "color",
    "$value": {
      "colorSpace": "srgb",
      "components": [0.15, 0.39, 0.92],
      "hex": "#2563eb"
    },
    "$description": "Primary brand color"
  }
}

Token Types

Atomic: color, dimension, fontFamily, fontWeight, duration, cubicBezier, number

Composite: strokeStyle, border, shadow, gradient, typography, transition

See reference/format.md for complete type definitions.

Color Format

Colors use structured objects (not hex strings):

{
  "$type": "color",
  "$value": {
    "colorSpace": "srgb",
    "components": [1, 0, 0.5],
    "alpha": 0.8,
    "hex": "#ff0080"
  }
}

Supported spaces: srgb, display-p3, oklch, oklab, hsl, hwb, lab, lch, and more. See reference/color.md.

References (Aliasing)

Two syntaxes supported:

1. Curly braces – Token-level references: "{path.to.token}"
2. JSON Pointer ($ref) – Property-level access: {"$ref": "#/path/to/$value/property"}

Token reference example:

{
  "color": {
    "primary": {"$type": "color", "$value": {"colorSpace": "srgb", "components": [0, 0.4, 0.8]}}
  },
  "button": {
    "background": {"$type": "color", "$value": "{color.primary}"}
  }
}

JSON Pointer example (accessing array elements):

{
  "blue": {
    "$type": "color",
    "$value": {"colorSpace": "okhsl", "components": [0.733, 0.8, 0.5]}
  },
  "blue-hue": {
    "$type": "number",
    "$ref": "#/blue/$value/components/0"
  }
}

See reference/format.md for complete reference syntax details.

Groups and Type Inheritance

Groups organize tokens. $type on a group applies to all children:

{
  "spacing": {
    "$type": "dimension",
    "sm": {"$value": {"value": 8, "unit": "px"}},
    "md": {"$value": {"value": 16, "unit": "px"}},
    "lg": {"$value": {"value": 24, "unit": "px"}}
  }
}

Resolvers for Theming

Resolvers manage tokens across contexts (themes, platforms, densities):

{
  "name": "my-system",
  "version": "2025.10",
  "sets": {
    "core": {"sources": [{"$ref": "tokens/base.json"}]}
  },
  "modifiers": {
    "theme": {
      "contexts": {
        "light": [{"$ref": "themes/light.json"}],
        "dark": [{"$ref": "themes/dark.json"}]
      },
      "default": "light"
    }
  },
  "resolutionOrder": [
    {"$ref": "#/sets/core"},
    {"$ref": "#/modifiers/theme"}
  ]
}

See reference/resolver.md for complete documentation.

Getting Started Guides

Quick Start: Convert CSS Variables to DTCG

Starting point: Existing CSS custom properties

:root {
  --color-primary: #2563eb;
  --color-background: #ffffff;
  --spacing-sm: 8px;
  --spacing-md: 16px;
}

Step 1: Create primitives.tokens.json

{
  "color": {
    "primitive": {
      "$type": "color",
      "blue-500": {
        "$value": { "colorSpace": "srgb", "components": [0.145, 0.388, 0.922], "hex": "#2563eb" }
      },
      "white": {
        "$value": { "colorSpace": "srgb", "components": [1, 1, 1], "hex": "#ffffff" }
      }
    }
  },
  "spacing": {
    "$type": "dimension",
    "scale": {
      "sm": { "$value": { "value": 8, "unit": "px" } },
      "md": { "$value": { "value": 16, "unit": "px" } }
    }
  }
}

Step 2: Create semantic.tokens.json with references

{
  "color": {
    "interactive": {
      "$type": "color",
      "primary": { "$value": "{color.primitive.blue-500}" }
    },
    "background": {
      "$type": "color",
      "page": { "$value": "{color.primitive.white}" }
    }
  },
  "spacing": {
    "$type": "dimension",
    "component": {
      "padding": { "$value": "{spacing.scale.sm}" },
      "gap": { "$value": "{spacing.scale.md}" }
    }
  }
}

Conversion tips:

• RGB hex to sRGB: divide each channel by 255 (e.g., 37/255 = 0.145)
• Keep hex as fallback in the hex property
• Create semantic layer for purpose-driven naming

Quick Start: Set Up Terrazzo with Dark Mode

Step 1: Install dependencies

npm install -D @terrazzo/cli @terrazzo/plugin-css

Step 2: Create token files with mode extensions

tokens/themes/light.tokens.json:

{
  "$extensions": { "mode": "light" },
  "color": {
    "background": {
      "$type": "color",
      "page": { "$value": { "colorSpace": "srgb", "components": [1, 1, 1], "hex": "#ffffff" } }
    },
    "text": {
      "$type": "color",
      "primary": { "$value": { "colorSpace": "srgb", "components": [0.07, 0.07, 0.07], "hex": "#121212" } }
    }
  }
}

tokens/themes/dark.tokens.json:

{
  "$extensions": { "mode": "dark" },
  "color": {
    "background": {
      "$type": "color",
      "page": { "$value": { "colorSpace": "srgb", "components": [0.07, 0.07, 0.07], "hex": "#121212" } }
    },
    "text": {
      "$type": "color",
      "primary": { "$value": { "colorSpace": "srgb", "components": [0.95, 0.95, 0.95], "hex": "#f2f2f2" } }
    }
  }
}

Step 3: Create terrazzo.config.mjs

import { defineConfig } from "@terrazzo/cli";
import pluginCSS from "@terrazzo/plugin-css";

export default defineConfig({
  tokens: [
    "./tokens/primitives.tokens.json",
    "./tokens/themes/light.tokens.json",
    "./tokens/themes/dark.tokens.json"
  ],
  outDir: "./dist/",
  plugins: [
    pluginCSS({
      filename: "tokens.css",
      modeSelectors: [
        { mode: "light", selectors: [":root", "[data-theme='light']"] },
        { mode: "dark", selectors: ["[data-theme='dark']", "@media (prefers-color-scheme: dark)"] }
      ]
    })
  ]
});

Step 4: Build and use

npx terrazzo build

In your HTML:

<html data-theme="light"><!-- or "dark" -->

Quick Start: Import Figma Variables Export

Step 1: Export from Figma

• Open Variables panel in Figma
• Use a DTCG export plugin or Figma’s built-in export
• Save as figma-export.json

Step 2: Validate the export

# Check JSON is valid
jq '.' figma-export.json > /dev/null && echo "Valid JSON"

# List all token paths
jq -r 'paths(has("$value")) | join(".")' figma-export.json

Step 3: Add mode extensions if needed

If Figma exported separate mode files, add $extensions.mode:

# Add mode to light theme file
jq '. + {"$extensions": {"mode": "light"}}' light.json > light.tokens.json

Step 4: Add hex fallbacks (if missing)

Figma exports sRGB components but may omit hex:

# Quick check if hex values exist
jq '.. | objects | select(.colorSpace == "srgb") | select(.hex == null)' figma-export.json

Step 5: Configure Terrazzo

Create terrazzo.config.mjs pointing to your imported files and build.

Common Figma export issues:

• Flat structure (no primitives/semantic separation) – reorganize manually
• Space in token names – use jq to convert to kebab-case
• Missing $type on groups – add type inheritance

Workflows

Creating a Token File

Token File Creation:
- [ ] Step 1: Define file structure (primitives → semantic → components)
- [ ] Step 2: Create primitive tokens with explicit types
- [ ] Step 3: Create semantic tokens referencing primitives
- [ ] Step 4: Validate structure and references
- [ ] Step 5: Test with target tools (Terrazzo, etc.)

Step 1: Define structure

Organize into layers:

tokens/
├── primitives.tokens.json   # Raw values (colors, spacing scales)
├── semantic.tokens.json     # Purpose-driven aliases
└── components.tokens.json   # Component-specific tokens

Step 2: Create primitives

{
  "color": {
    "primitive": {
      "$type": "color",
      "blue": {
        "500": {"$value": {"colorSpace": "srgb", "components": [0.15, 0.39, 0.92], "hex": "#2563eb"}}
      }
    }
  }
}

Step 3: Create semantic tokens

{
  "color": {
    "interactive": {
      "$type": "color",
      "default": {"$value": "{color.primitive.blue.500}"}
    }
  }
}

Step 4: Validate

Check for:

• All tokens have resolvable $type
• No circular references
• Valid value formats for each type
• Names don’t contain {, }, . or start with $

Step 5: Test with tools

terrazzo validate tokens.json
terrazzo build --input tokens.json --output test.css --format css

Setting Up a Theme Resolver

Resolver Setup:
- [ ] Step 1: Organize token files by concern
- [ ] Step 2: Create resolver.json with version and sets
- [ ] Step 3: Define theme modifier with contexts
- [ ] Step 4: Configure resolution order
- [ ] Step 5: Test with different inputs

Step 1: Organize files

tokens/
├── resolver.json
├── base.tokens.json
└── themes/
    ├── light.tokens.json
    └── dark.tokens.json

Step 2: Create resolver

{
  "name": "my-design-system",
  "version": "2025.10",
  "sets": {
    "foundation": {
      "sources": [{"$ref": "base.tokens.json"}]
    }
  }
}

Step 3: Define theme modifier

{
  "modifiers": {
    "theme": {
      "contexts": {
        "light": [{"$ref": "themes/light.tokens.json"}],
        "dark": [{"$ref": "themes/dark.tokens.json"}]
      },
      "default": "light"
    }
  }
}

Step 4: Set resolution order

{
  "resolutionOrder": [
    {"$ref": "#/sets/foundation"},
    {"$ref": "#/modifiers/theme"}
  ]
}

Step 5: Test

terrazzo build --resolver resolver.json --output light.css
terrazzo build --resolver resolver.json --input theme=dark --output dark.css

Validating Token Files

Validation Checklist:
- [ ] Step 1: Check JSON syntax
- [ ] Step 2: Verify type declarations
- [ ] Step 3: Validate value formats
- [ ] Step 4: Check reference resolution
- [ ] Step 5: Verify naming constraints

Step 1: JSON syntax

jq '.' tokens.json > /dev/null && echo "Valid JSON"

Step 2: Type declarations

Every token needs a resolvable $type (explicit or inherited from parent group).

Step 3: Value formats

Step 4: References

• All {path.to.token} references must resolve
• No circular references (A → B → A)
• No self-references

Step 5: Naming

• Names cannot start with $
• Names cannot contain {, }, .

Migrating from Other Formats

Migration Workflow:
- [ ] Step 1: Export existing tokens to JSON
- [ ] Step 2: Map types to DTCG equivalents
- [ ] Step 3: Convert color values to structured format
- [ ] Step 4: Update reference syntax
- [ ] Step 5: Validate and test

Common conversions:

Terrazzo conversion:

terrazzo convert --from style-dictionary --to dtcg input.json output.tokens.json

Best Practices

Token Layers

1. Primitives – Raw values without semantic meaning
2. Semantic – Purpose-driven tokens referencing primitives
3. Component – Specific component tokens referencing semantic

Naming Conventions

• Use lowercase with hyphens: color.brand.primary
• Structure: [category].[subcategory].[variant].[state]
• Semantic over appearance: color.interactive.default not color.blue-500

Theming Strategy

Use resolvers for themes (recommended over group extension):

• Cleaner separation of concerns
• Token paths stay consistent across themes
• Easy to compose themes (e.g., dark + high-contrast)
• Standardized input handling for build tools

Accessibility

Color contrast: Document contrast ratios in $extensions:

{
  "$extensions": {
    "com.example.a11y": {"contrastRatio": 7.5, "wcagLevel": "AA"}
  }
}

Reduced motion: Use resolver modifier:

{
  "modifiers": {
    "motion": {
      "contexts": {
        "full": [{"$ref": "motion/full.json"}],
        "reduced": [{"$ref": "motion/reduced.json"}]
      },
      "default": "full"
    }
  }
}

File Conventions

• Token files: .tokens or .tokens.json
• Resolver files: .resolver.json
• Encoding: UTF-8

Common Tasks

Your Role

When helping with design tokens:

1. Verify before claiming – Check reference files before stating what DTCG does/doesn’t support. Never assume spec limitations.
2. Use latest DTCG spec – Structured color format, proper types
3. Validate structure – Check $value, $type, references
4. Suggest best practices – Naming, organization, layering
5. Help with tools – jq queries, Terrazzo commands, JSONata transforms
6. Consider platforms – Web, iOS, Android via $extensions
7. Think about scale – Design for maintainability
8. Prioritize accessibility – Contrast, motion, focus indicators
9. Connect design and code – Bridge tools and implementation

Important: When asked about spec capabilities (what syntax is valid, what features exist), always read the relevant reference file first. Do not rely on assumptions or prior knowledge about the spec.

Always provide clear examples and explain reasoning behind recommendations.