dtcg export omits required typography properties, so output fails the schema it declares

[rvratner]

What happened

export --format dtcg emits typography tokens that are missing two of the five properties the DTCG typography value schema marks as required, so the output does not validate against the schema it declares in its own $schema field.

Reproduction

Any spec with a typography section — here olmo-earth/DESIGN.md from allenai/design.md:

npx @google/design.md@0.4.0 export --format dtcg olmo-earth/DESIGN.md | jq '.typography["body-md"]'

{
  "$type": "typography",
  "$value": {
    "fontFamily": "Manrope, Arial, sans-serif",
    "fontSize": { "value": 16, "unit": "px" },
    "fontWeight": 400
  }
}

The source frontmatter for that role is:

body-md:
  fontFamily: "{typography.font-body}"
  fontSize: 16px
  fontWeight: 400
  lineHeight: 1.6

Why it's a problem

The emitted document declares "$schema": "https://www.designtokens.org/schemas/2025.10/format.json". That schema's typography value definition:

properties: fontFamily, fontSize, fontWeight, letterSpacing, lineHeight
required:   fontFamily, fontSize, fontWeight, letterSpacing, lineHeight
additionalProperties: false

All five are required. The export emits three, so every typography token fails validation — 10 of 10 in the spec above, each missing letterSpacing and lineHeight.

lineHeight is the one that bites in practice: it's present in the source frontmatter and silently dropped, so a consumer round-tripping through DTCG loses it. (letterSpacing isn't in the DESIGN.md format at all, so it has no source value — worth deciding whether to emit a default, omit the $type, or target a profile that doesn't require it.)

Suggested fixes, in order of preference

1. Emit lineHeight from the frontmatter, and emit letterSpacing with an explicit default ("0" / {value: 0, unit: "px"}) so the token validates.
2. If a required property genuinely has no source value, drop $type: "typography" for that token and emit the sub-values as a plain group — invalid-by-omission is worse than untyped.
3. Failing either, stop advertising the 2025.10 $schema in the output, so downstream validators don't reject a file that claims conformance.

Happy to send a PR for option 1 if that's the direction you'd want.

Environment

@google/design.md@0.4.0, Node 25.2.1, macOS.

[jaredmcateer]

I found out the hard way not knowing that line height could only be a number in dtcg tokens that if you add a valid dimension unit in the design.md frontmatter that the export does output a value and simply ignores the unit (22px becoming a 22 mulitplier was a little shocking).

Edit: It also appears quoting unitless numbers will export the values as numbers to tokens

code:
  fontFamily: monospace
  fontSize: 13px
  fontWeight: "400"
  lineHeight: "1.538"

npx @google/design.md export --format dtcg DESIGN.md

{
    "code": {
      "$type": "typography",
      "$value": {
        "fontFamily": "monospace",
        "fontSize": {
          "value": 13,
          "unit": "px"
        },
        "fontWeight": 400,
        "lineHeight": 1.538
      }
    }
}