Extract Design System

Extract a full design system bundle

Given a live URL, run the 9-stage pipeline and emit a bundle under .design_systems/<domain>-YYYYMMDD/ (host dots→hyphens). The output bundle layout and the AGENTS.md consumption template are specified in references/output-bundle-spec.md.

URL ─▶ 1 DISCOVER ─▶ 2 TOKENS ─▶ 3 COMPONENT SWEEP ─▶ 4 CLUSTER + CURATE
    ─▶ 5 DISTILL ─▶ 6 STATES ─▶ 7 SECTIONS ─▶ 8 SYNTHESIZE ─▶ 9 VALIDATE

Prerequisites

This skill drives three external tools — make sure each is available before running:

• playwright-cli on PATH — the in-browser extraction, component sweep, and screenshots run through it. Install once with npm install -g @playwright/cli@latest then playwright-cli install --skills (needs Node.js 18+). Check: which playwright-cli.
• A reachable Firecrawl instance — used for page discovery (firecrawl map) and optional copy scraping. The hosted API or a self-hosted / local instance both work; if Firecrawl is unreachable the skill falls back to playwright link discovery (thinner page coverage). Confirm your instance responds before a run.
• npx (Node.js) — pulls the official @google/design.md linter on demand for the quality gate. If it's unavailable the skill writes the files anyway and notes "lint skipped".

If your agent sandboxes network or filesystem access, allow the outbound calls this skill makes (headless browsing, Firecrawl, npx) before running.

file:// URLs are blocked by playwright-cli — serve local HTML with python3 -m http.server <port> and kill the server by PID afterwards (a pkill -f pattern can match your own shell).

Let SKILL = this skill's directory. Session name: S=dsys. Compose→run→slice pattern for every in-page script:

playwright-cli -s=$S run-code "$(cat script.js)" | bash "$SKILL/scripts/slice-result.sh" > out.json

Two scripts are templates with a __-placeholder substituted per page (distill.js → COMPONENTS, eval-selftest.js → FIXTURES). Compose with tpl.replace('<placeholder>', JSON), then node --check the result. The placeholder literal must appear exactly once in each template, in code — never add it to a comment (this bug has now happened twice).

Flags

Conflict guard (standing rule): if the output folder exists, ask (overwrite / dated sibling / abort). Never silently resolve.

Stage 1 — Discover

firecrawl map "<url>" → bucket into slots (home always; pricing/product for cards+ toggles+tables; auth/contact for inputs; blog for prose; brand/about). Component coverage weights the choice: prefer pages exposing form controls, repeated cards, tables. Confirm the picked list with the user before crawling. Firecrawl down → try starting it, else playwright link discovery.

Stage 2 — Tokens

scripts/extract-tokens.js (verbatim from extract-design-md — dual-theme detection and toggling rules are in that skill's references/edge-cases.md). Run on the homepage per theme; finalize the token table before stage 5 so distillation can re-tokenize. Sanity-check varsTotal; thin vars → relax using varsExtra.

Stage 3 — Component sweep (per sampled page)

Scroll the page first to trigger lazy content (step ~900px, then back to top), then run scripts/extract-components.js. It merges two channels (semantic tags/roles/class-regex

• structural fingerprints), scores component-ness (fake-interactive and sub-10px-font penalties keep DOM-built demo UIs out), detects the styling regime (tailwind density / hashed classes / library fingerprints), and returns top-N candidates per kind with 17-dim style vectors. Save one candidates-<slug>.json per page.

Stage 4 — Cluster + curate

node "$SKILL/scripts/cluster.js" candidates-home.json candidates-pricing.json > clusters.json

Deterministic: greedy-leader clustering (cosine ≥0.95), per-property-mode representative, catalog gate (≥2 instances site-wide OR semantic/landmark role). Then Claude curates: name components/variants (class-name hints beat inference: btn--secondary → secondary; transparent → ghost; most-common → primary), merge duplicates, drop noise, trim to --max-components, flag low-confidence picks. Output a curated list per page: [{ name, sel, expectText }] (expectText = the element's leading text, for brittle-selector re-resolution).

Stage 5+6 — Distill + states (per page)

Compose scripts/distill.js with the page's curated array (each entry may add budget: <n>; default 12 descendants). Returns per component: simplified HTML with data-src-class verbatim recipes, default-diffed CSS, CDP authored rules, forced hover/focus diffs on 13 tracked props, transition. Components that error return {name, error} — rerun or drop, never crash. Save distilled-<slug>.json.

Stage 7 — Sections (per page)

Scroll first, then run scripts/extract-sections.js → pattern + confidence + skeleton + atomEvidence per section. Curate: needsSmart (<0.5) entries you label yourself from heading/atomEvidence/screenshot (may be custom:<name>); override misclassifications; pick ONE representative per pattern (≤8 total, ranked confidence × instances); log every skip with a reason (goes to raw/skipped.json). Distill each representative via the stage-5 template with budget: 40. Screenshot each section crop (page.locator(sel).scrollIntoViewIfNeeded() then .screenshot()) into screenshots/sections/.

Stage 8 — Synthesize the bundle

Layout (see references/output-bundle-spec.md for the full spec — read it before writing):

<out>/
├── DESIGN.md                    # ≤300 lines; extract-design-md prose + `## Component Catalog` table
├── AGENTS.md                    # consumption protocol (6 imperative steps; template in `references/output-bundle-spec.md`)
├── components/COMPONENTS.md     # ~15-line contracts: anatomy, variants×states, usage, screenshots
├── components/*.html + gallery.html
├── tokens/design-tokens.json    # DTCG export
├── eval/fixtures.json + checklists.md
├── screenshots/<page>.png + sections/ + states/
└── raw/                         # tokens/ candidates/ sections/ distill-log.json skipped.json map.json

Mechanical parts:

node "$SKILL/scripts/build-snippets.js" --tokens tokens.json --out <out>/components \
  --source <url> distilled-home.json distilled-pricing.json distilled-sections-*.json
node "$SKILL/scripts/export-dtcg.js" tokens.json <out>/tokens/design-tokens.json --source <url> --theme light
node "$SKILL/scripts/build-fixtures.js" --tokens tokens.json --components <out>/components \
  --out <out>/eval/fixtures.json --source <url> --theme light \
  home:distilled-home.json pricing:distilled-pricing.json home:distilled-sections-home.json ...

Claude-authored parts: DESIGN.md (dual-theme rules as in extract-design-md; add the Component Catalog table + a section-rhythm paragraph in Layout), COMPONENTS.md (anatomy from the snippet HTML, variants×states from fixtures/states data, composition+skeleton lines for sections, low-confidence flags visible), AGENTS.md, eval/checklists.md (per-component judge rubrics; axis scores recorded separately, never averaged). Contract accuracy (consumers follow these lines literally): every Composition claim must be verifiable in the reference snippet's markup (elements seen elsewhere → marked optional); content-dependent elements (billing toggles, testimonials) marked conditional — omit, don't invent; prose type-size claims must match the measured reference, not a plausible generalization. State screenshot crops: serve <out>/components locally, screenshot the .is-hover/ .is-focus copies into screenshots/states/.

Stage 9 — Validate (all four gates before reporting)

1. Lint: npx -y @google/design.md lint <out>/DESIGN.md — fix structural errors; flag value warnings, never silently delete captured tokens.
2. Gallery: render gallery.html headless via the local server; 0 console errors required; screenshot and eyeball against the source screenshots.
3. Eval self-test: compose scripts/eval-selftest.js with fixtures.json; run on every sampled page of the LIVE source. Every check must pass — a failure means the fixture (or extraction) is wrong: fix or drop, never ship a fixture the source itself fails. Archive results to raw/.
4. Completeness: every high-count candidate kind is a catalog entry or a reasoned entry in raw/skipped.json.

Final report

Tight and honest: pages sampled, regime detected, atoms + sections found (counts), curation skips, lint result verbatim, self-test pass counts, fallback paths taken, known gaps (e.g. un-captured selected-state indicators). Never imply fidelity a gate didn't verify.

Ask-first rule (standing)

<95% confident on an ambiguous mapping (which variant is "primary", whether a repeated block is a real pattern, same-day output conflicts) → ask with a recommendation. Sub-agents run sequentially, never in parallel, and must carry the Firecrawl + sandbox rules above.

Bundled files

• scripts/extract-tokens.js — stage-2 token extractor (copy of extract-design-md's; keep in sync)
• scripts/extract-components.js — stage-3 sweep (two channels, scoring, regime detection)
• scripts/cluster.js — stage-4 deterministic clustering + catalog gate (node CLI)
• scripts/distill.js — stage-5/6 template (COMPONENTS placeholder; per-entry budget)
• scripts/extract-sections.js — stage-7 classifier (self-contained run-code)
• scripts/build-snippets.js — stage-8 snippet/gallery emitter (node CLI)
• scripts/export-dtcg.js — stage-8 DTCG export (node CLI)
• scripts/build-fixtures.js — stage-8 fixtures generator (node CLI; evidence-only assertions)
• scripts/eval-selftest.js — stage-9 self-test template (FIXTURES placeholder; CIEDE2000, CDP states)
• scripts/slice-result.sh — strips playwright-cli's markdown wrapper to clean JSON
• references/output-bundle-spec.md — the output bundle layout + AGENTS.md consumption template. Read before Stage 8.