Design Extract

Extract a live website's design system and write the results into brain/brand-guide/brand-guide.md.

Uses designlang — a headless-browser tool that reads the design system off the live DOM and emits structured tokens.

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Prerequisites

• Node 20+
• designlang CLI (installed automatically if missing)

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Workflow

Step 1: Get the URL

Ask the user:

What website URL should I extract the design system from?

If they already provided a URL in their message, confirm it.

Optional follow-ups:

• "Should I extract dark mode too?" (adds --dark flag)
• "Any pages behind auth I should include?" (adds --cookie flag)

Step 2: Install designlang if needed

Check if designlang is available:

export PATH="$PATH:/opt/homebrew/bin:/usr/local/bin"; command -v designlang || npm list -g designlang 2>/dev/null

If not installed, use npx to avoid global install permission issues:

npx -y designlang <url> ...

Alternatively, if the user prefers a global install:

npm i -g designlang

Step 3: Run extraction

Run designlang's brand subcommand against the URL. This generates a full editorial brand-guidelines document (13 chapters, print-ready) along with design tokens:

designlang brand <url> --out ./design-extract-output --name brand --verbose

If the brand subcommand fails or produces insufficient output, fall back to the default extraction:

designlang <url> --out ./design-extract-output --name brand --full --verbose

Flags to consider based on user input:

• --dark — if they want dark mode tokens
• --depth 2 — if they want to crawl beyond the homepage
• --cookie "name=value" — if pages require auth

Step 4: Parse the output

Read the generated files from ./design-extract-output/:

1. brand-design-language.md — the full 19-section design system doc
2. brand-design-tokens.json — W3C DTCG tokens (colors, typography, spacing)
3. brand-voice.json — tone, CTA verb inventory (pass to tone-mapping if present)

Extract and organize:

• Colors: core palette, accent colors, semantic colors (success, error, warning), gradients
• Typography: font families, weights, sizes, line heights, font sources
• Spacing: base unit, scale tokens
• Buttons: primary/secondary styles, border radius, padding, hover states
• Design principles: inferred from patterns (dark-first vs light, density, whitespace approach)

Step 5: Review with user

Present the extracted design system in a summary table format:

Extracted from: [url]

Colors:
  Primary Background    #1a1a2e
  Card Background       #16213e
  Primary Text          #ffffff
  Body Text             #a8b2d1
  Primary Accent        #0f3460    (buttons, CTAs)
  Secondary Accent      #e94560    (highlights)

Typography:
  Headings    Inter         700    fallback: system-ui
  Body        Inter         400    fallback: system-ui
  Code        JetBrains Mono 400   fallback: monospace

Spacing: 4px base unit (4, 8, 12, 16, 24, 32, 48, 64)

Buttons:
  Primary     #0f3460 bg, #fff text, 8px radius
  Secondary   transparent bg, #0f3460 border

Ask: "Does this look right? Anything to adjust before I write the brand guide?"

Step 6: Write brand-guide.md

Write the extracted values into brain/brand-guide/brand-guide.md, replacing [FILL IN] placeholders with real values. Preserve the template structure exactly — only replace placeholders.

If the extraction found values not covered by the template (gradients, shadows, z-index), add them as new sections at the bottom following the same formatting conventions.

Step 7: Clean up

Remove the design-extract-output/ directory:

rm -rf ./design-extract-output

Tell the user:

Brand guide updated at brain/brand-guide/brand-guide.md. All visual skills (brand-design, web-design, hubspot-email, etc.) will now use these values.

If brand-voice.json contained tone/voice data, mention:

I also found voice/tone data. Run /tone-mapping to build a full voice profile.

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Rules

• Never overwrite existing brand-guide values without confirming with the user
• If the brand guide already has values filled in, show a diff of what would change and ask
• If designlang fails (site blocks headless browsers, JS-heavy SPA that doesn't render), tell the user and offer manual entry as fallback
• Keep the design-extract-output directory until the user confirms the brand guide looks good, then clean up
• If the site has both light and dark modes, extract both and present both, letting the user pick which is primary