Extract Static HTML

Extract a self-contained static HTML file from any web application.

Which Strategy to Use

You MUST ask the user to choose which strategy to use before proceeding. Present the options clearly, recommend Strategy A as the preferred default, and provide a brief pros/cons summary for each option to help them make an informed decision.

	Strategy A (Puppeteer)	Strategy B (Browser Subagent)
When	App runs locally, no auth wall	Need to interact with page first (click, fill forms)
Fidelity	Highest — computed styles resolved	High — rendered DOM
Setup	Zero — no mock needed	Zero — no mock needed
Framework	Any	Any
Output	Writes to file — no size limit	May truncate in agent context

[!WARNING] Checkpoint — User Confirmation Required. You MUST ask the user which strategy they prefer before proceeding. Present the comparison table above, recommend Strategy A as the default, and wait for explicit approval. Do NOT make the decision yourself or proceed until the user confirms.

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Strategy A: Puppeteer Snapshot (Recommended)

Launches headless Chrome, captures the fully rendered DOM, and produces a self-contained HTML file with all CSS inlined and images as base64. Works with any framework — no MockPage.jsx needed.

Prerequisites

• App running locally (e.g., npm run dev)
• Node.js with puppeteer available (check: node -e "require('puppeteer')")

Workflow

1. Start the App and note the port.

   [!WARNING] Checkpoint — User Confirmation Required. After starting the local server, you MUST pause and ask the user for confirmation before running the snapshot script or launching a browser subagent. Report the URL and port to the user so they can verify the app is running and rendering correctly. Do NOT proceed to the snapshot step until the user confirms.

2. Run the Snapshot Script:

   npx tsx <SKILL_DIR>/scripts/snapshot.ts \
     --url http://localhost:5173 \
     --output .stitch/home.html \
     --wait 2000
   

3. Multiple pages — run once per route:

   npx tsx <SKILL_DIR>/scripts/snapshot.ts \
     --url http://localhost:5173 --output .stitch/home.html --wait 2000
   npx tsx <SKILL_DIR>/scripts/snapshot.ts \
     --url http://localhost:5173/pricing --output .stitch/pricing.html --wait 2000
   npx tsx <SKILL_DIR>/scripts/snapshot.ts \
     --url http://localhost:5173/dashboard --output .stitch/dashboard.html --wait 2000 --html-class dark
   

4. Clean Up Dev Server: If a local dev server was started specifically for snapshot extraction, make sure to stop the server process or terminate the background task once extraction is completed.

Script Flags

Flag	Default	Description
--url	(required)	URL to capture
--output	(required)	Output file path
--wait	1000	Extra wait (ms) after network idle. Increase for lazy-loading apps.
--viewport	1280x800	Viewport size as WIDTHxHEIGHT
--html-class	—	Class(es) for <html> element (e.g., dark)
--remove-fixed	false	Remove fixed/sticky elements (cookie banners, chat widgets)
--full-height	false	Resize viewport to full scroll height
--title	—	Override page title (set to the route path, e.g. /dashboard or /settings/profile)
--auth-script	—	Path to a JS/TS module that exports a default async (page) => void function for authentication
--inline-canvas	false	Convert <canvas> elements (ECharts, Chart.js, D3) to base64 <img> tags

What It Does Automatically

• Captures all CSSOM rules from document.styleSheets (preserves dynamic Vite/Tailwind dev styles and CSS-in-JS)
• Inlines all <link rel="stylesheet"> → <style> blocks
• Converts <img> src and srcset → base64 data URIs (skips external fonts)
• Inlines same-origin and relative icon font files (@font-face) as base64 data URIs so ligatures never render as ASCII text
• Inlines <source srcset> URLs as base64
• Removes failed/dead srcset entries so the browser falls back to the inlined src
• Removes <script> tags, Vite HMR dev style blocks (createHotContext, import.meta.hot), and dev overlays
• Resolves relative CSS url() paths before inlining

Framework Notes

Framework	Notes
React + Vite	Works out of the box. --wait 1000.
Next.js	--wait 3000 for SSR hydration. URL: http://localhost:3000. <img srcset> from /_next/image is auto-inlined as base64.
Angular (@angular/cli / v17+)	Works out of the box with ng serve (default URL: http://localhost:4200). --wait 2000 for Angular Material / PrimeNG animation hydration and lazy-loaded routes.
Vue / Nuxt	Works out of the box.
Svelte / SvelteKit	Works out of the box.
Storybook	Use story URL: --url http://localhost:6006/?path=/story/...
SSR (Webpack)	May need longer --wait.

Troubleshooting

Issue	Solution
Images missing	Increase --wait
Images show as broken after server stops	Verify srcset was inlined — check log for "Inlined N images". If srcset URLs failed, they are auto-removed so src (inlined) is used.
Icons display as text / Serif unstyled font	Ensure snapshot.ts captures CSSOM from document.styleSheets (step 0) and same-origin icon fonts (@font-face) are inlined as base64 data URIs.
Next.js /_next/image not inlined	Ensure the dev server is running when snapshot runs — the script fetches optimized images from the running server.
Dark mode not applied	--html-class dark
Cookie banner in output	--remove-fixed
Page requires login	Use --auth-script ./auth.ts (see Auth-Gated Pages below)
Charts/graphs show as blank boxes	Use --inline-canvas to serialize <canvas> to base64 <img>
Cannot find module 'puppeteer'	npm install -g puppeteer

Auth-Gated Pages

For apps with login guards (Vue Router beforeEach, React ProtectedRoute, etc.), create a small auth script that runs in the Puppeteer session:

// auth-myapp.ts
import type { Page } from 'puppeteer';

export default async function authenticate(page: Page) {
  // Example 1: Fill and submit a login form
  await page.type('#username', 'admin');
  await page.type('#password', 'password123');
  await page.click('#login-button');
  await page.waitForNavigation({ waitUntil: 'networkidle2' });

  // Example 2: Inject cookies/localStorage directly
  // await page.evaluate(() => {
  //   localStorage.setItem('token', 'mock-jwt-token');
  // });

  // Example 3: Call the app's own login API via module injection (Vue/Vite)
  // await page.evaluate(() => {
  //   return new Promise((resolve) => {
  //     const script = document.createElement('script');
  //     script.type = 'module';
  //     script.textContent = `
  //       import { useUserStore } from '/src/store/modules/user.ts';
  //       import { fetchLogin } from '/src/api/auth.ts';
  //       const res = await fetchLogin({ userName: 'Admin', password: '123456' });
  //       useUserStore().setToken(res.token, res.refreshToken);
  //       window.dispatchEvent(new CustomEvent('auth-done'));
  //     `;
  //     document.head.appendChild(script);
  //     window.addEventListener('auth-done', () => resolve(true), { once: true });
  //   });
  // });
}

Then use it:

npx tsx <SKILL_DIR>/scripts/snapshot.ts \
  --url http://localhost:5173/#/dashboard \
  --output .stitch/dashboard.html \
  --auth-script ./auth-myapp.ts \
  --inline-canvas \
  --wait 5000

The script navigates to the --url first (which may redirect to login), runs your auth function, then re-navigates to the original --url with the authenticated session.

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Strategy B: Browser Subagent Capture

Use when you need to interact with the page (click buttons, fill forms, navigate tabs) before capturing. The browser subagent gives you full control but output may truncate for large pages.

Workflow

1. Start the App locally.

2. Navigate using a browser subagent.

3. Interact as needed (click, scroll, fill forms).

4. Extract DOM: document.documentElement.outerHTML

   [!WARNING] Large pages may truncate. To handle this:

   • Remove <style> tags before extraction: document.querySelectorAll('style').forEach(el => el.remove())
   • Re-add styles statically (Tailwind CDN link, source CSS)

5. Save to file.

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Appendix: Static Fallback (MockPage.jsx)

[!NOTE] This method is a last resort for when the app cannot run locally (broken deps, missing backend, auth walls with no bypass). It requires manually flattening React components into a single JSX file. Prefer Strategy A whenever possible.

When to Use

• App can't run locally at all
• Page requires auth with no mock/bypass
• You need a specific UI state that's impossible to reach by navigation (error screens, empty states)

Quick Reference

npx tsx <SKILL_DIR>/scripts/extract_inline_html.ts \
  --index-css src/css/App.css \
  --extra-css index.html \
  --outdir .stitch \
  --page src/MockPage.jsx:Page.html:"Page Title"

Key flags: --no-tailwind (non-Tailwind apps), --html-class dark (dark mode), --css-files (extra CSS files).

Auto-detection: Tailwind config is auto-detected. @apply directives automatically use <style type="text/tailwindcss">.

MockPage.jsx Rules

1. Include the full layout — header, sidebar, footer (read App.js first)
2. Flatten all conditionals — pick one state, remove all ternaries and && guards
3. Hardcode all data — replace {variable} with concrete values, unroll .map() loops
4. Preserve logos — use <img> with local paths (post-process will inline them)
5. Remove floating elements — cookie banners, chat widgets, feedback buttons

Post-Processing

Inline local images:

npx tsx <SKILL_DIR>/scripts/post_process.ts \
  .stitch/Page.html --base-dir <app-directory>

Anti-Patterns

• Claiming a Stitch screen-generation, screen-editing, or screen-retrieval MCP call succeeded when the active host does not expose that tool.
• Uploading files, screenshots, HTML, markdown, or design assets to Stitch without user-approved destination and artifact details.
• Reading, printing, storing, or committing Stitch API keys, MCP config secrets, cookies, or credential-bearing files.
• Treating generated design or code as final without local render, syntax, or artifact verification.
• Collapsing this workflow into a broader frontend/design skill when Stitch-specific files, project IDs, or design-system assets matter.

Verification Protocol

Before claiming this skill was applied successfully:

1. Pass/fail: The output HTML exists under .stitch/.
2. Pass/fail: Capture route, viewport, wait time, and special flags are recorded.
3. Pass/fail: Important images are inlined or intentionally left as stable external URLs.
4. Pass/fail: No authenticated personal content, cookies, tokens, or private user data were captured.
5. Pressure-test scenario: Repeat the workflow with Stitch MCP screen tools unavailable and confirm the fallback path remains honest and actionable.
6. Success metric: The user can identify the exact artifact, project/design-system target, and verification evidence without relying on unstated MCP behavior.

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Cross-Client Portability

This skill is written to stay usable across GitHub Copilot, Claude Code, and Codex.

• GitHub Copilot: keep the folder in a Copilot-visible skill path or wrap the workflow in project instructions when folder discovery is unavailable.
• Claude Code: keep the folder in a local skills directory or a compatible plugin source.
• Codex: install or sync the folder into $CODEX_HOME/skills/stitch-extract-static-html and restart Codex after major changes.

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MCP Availability And Fallback

Preferred MCP Server: Stitch MCP

• Fallback prompt: "Use the Stitch Extract Static HTML skill without Stitch MCP. Use browser export or a manually flattened mock component when Puppeteer is unavailable, then document fidelity limits. Show the exact files, commands, manual Stitch UI steps, and verification evidence used before concluding."
• Verified Stitch MCP tools in this workspace are design-system/project oriented; use broader screen tools only when the current host exposes them.
• Use local scripts, exported HTML/screenshots, the Stitch web UI, and project metadata files as the fallback evidence path.

<!-- MCP:END -->

Related Skills

• stitch-code-to-design: Use when the task also needs this adjacent Stitch workflow.
• stitch-upload-to-stitch: Use when the task also needs this adjacent Stitch workflow.
• web-testing: Use when the task also needs this adjacent Stitch workflow.
• vite-development: Use when the task also needs this adjacent Stitch workflow.