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DesignDiff MCP

AI implementation verification engine for Figma and MCP-compatible coding agents.

DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.

Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why

AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:

  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.

The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.

Quick start

1. Get your Figma API keySettings → Account → Personal access tokens

2. Add to your agent config

Claude Code (~/.config/claude/mcp.json):

{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}

Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.

3. Say to your agent

"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.

Works best with Storybook, local preview routes, or any stable component URL your agent can render.

Tools

check_component_parity — ships now

Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.

check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})

What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.

What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.

flag_stale_mappings — ships now

Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.

flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})

Reads from .figma/code-connect.json in your repo root.

generate_sync_patch — ships now

Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.

generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})

audit_state_coverage — v0.2

Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.

check_responsive_parity — v0.2

Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.

check_theme_parity — v0.2

Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.

Finding your Figma IDs

File ID: From the URL — figma.com/file/{FILE_ID}/...

Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.

How it works

  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.

  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.

  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.

  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.

Configuration

Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)

HTTP transport

For use with non-stdio MCP clients:

FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp

Health check: GET /health

Development

git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start

Inspect tools interactively:

npm run inspector

This opens the MCP Inspector UI where you can call tools directly.

Roadmap

StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts

Contributing

See CONTRIBUTING.md.

License

MIT — see LICENSE.

By Mathew Graham

About

DesignDiff verifies that AI-generated interfaces match your design system before they reach production.

designdiff.netlify.app/

Topics

ai-toolsaidesignmcpmcp-serverqaqa-automation

Resources

Readme
MIT license

Contributing

Contributing
Activity

Stars

0 stars

Watchers

0 watching

Forks

0 forks
Report repository

Releases

Packages

Used by

Contributors

Languages

, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
Skip to content
BranchesTags
Repository files navigation
DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
Topics
ai-toolsaidesignmcpmcp-serverqaqa-automation
Resources
Readme
MIT license
Contributing
Contributing
Activity
Stars
0 stars
Watchers
0 watching
Forks
0 forks
Report repository
Releases
Packages
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
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document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
Skip to content
BranchesTags
Repository files navigation
DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
Topics
ai-toolsaidesignmcpmcp-serverqaqa-automation
Resources
Readme
MIT license
Contributing
Contributing
Activity
Stars
0 stars
Watchers
0 watching
Forks
0 forks
Report repository
Releases
Packages
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
Skip to content
BranchesTags
Repository files navigation
DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
Topics
ai-toolsaidesignmcpmcp-serverqaqa-automation
Resources
Readme
MIT license
Contributing
Contributing
Activity
Stars
0 stars
Watchers
0 watching
Forks
0 forks
Report repository
Releases
Packages
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
Skip to content
BranchesTags
Repository files navigation
DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
Topics
ai-toolsaidesignmcpmcp-serverqaqa-automation
Resources
Readme
MIT license
Contributing
Contributing
Activity
Stars
0 stars
Watchers
0 watching
Forks
0 forks
Report repository
Releases
Packages
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
Skip to content
BranchesTags
Repository files navigation
DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
Topics
ai-toolsaidesignmcpmcp-serverqaqa-automation
Resources
Readme
MIT license
Contributing
Contributing
Activity
Stars
0 stars
Watchers
0 watching
Forks
0 forks
Report repository
Releases
Packages
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
Skip to content
BranchesTags
Repository files navigation
DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
Topics
ai-toolsaidesignmcpmcp-serverqaqa-automation
Resources
Readme
MIT license
Contributing
Contributing
Activity
Stars
0 stars
Watchers
0 watching
Forks
0 forks
Report repository
Releases
Packages
Used by
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
GitHub - Valkyrie2048/DesignDiff: DesignDiff verifies that AI-generated interfaces match your design system before they reach production. · GitHub
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DesignDiff MCP
AI implementation verification engine for Figma and MCP-compatible coding agents.
DesignDiff verifies that AI-generated interfaces match your Figma design system before they ship. It reads the Figma spec, renders your component in a real browser, compares computed CSS output, and returns patch-ready fixes — all inside your existing coding agent session.
Claude Code / Cursor / Windsurf
↓
DesignDiff MCP
↓
Figma REST API + Playwright renderer
↓
Scored diff + Patch-ready fix
↓
Agent applies → Re-checks: 94/100

Why
AI agents generate UI code from Figma specs and get it mostly right — but not exactly. The typical failure pattern:
  • Token violations — hardcoded #2563EB instead of var(--brand-blue-600). Works today, breaks on the next brand refresh.
  • Spacing drift — padding is 12px not 16px because the agent approximated instead of reading the exact value.
  • Missing states — hover, focus, and disabled were defined in Figma variants the agent didn't parse.
The component looks correct visually. That's what makes this dangerous. DesignDiff catches these errors before they land in a PR.
Quick start
1. Get your Figma API keySettings → Account → Personal access tokens
2. Add to your agent config
Claude Code (~/.config/claude/mcp.json):
{
"mcpServers": {
"designdiff": {
"command": "npx",
"args": ["-y", "designdiff-mcp"],
"env": { "FIGMA_API_KEY": "your-token-here" }
}
}
}
Same format for Cursor (.cursor/mcp.json), Windsurf, VS Code Copilot, and Zed.
3. Say to your agent
"Build the Button component from Figma file abc123, node 123:456,
running at localhost:6006 — and verify it matches the spec"

DesignDiff is called automatically when the agent generates or modifies a component.
Works best with Storybook, local preview routes, or any stable component URL your agent can render.
Tools
check_component_parity — ships now
Diffs the Figma design spec against computed browser CSS. Returns a scored parity report with ranked mismatches and a patch-ready fix when score drops below threshold.
check_component_parity({file_id: "abc123",// Figma file ID from URLnode_id: "123:456",// Component node IDcomponent_url: "http://localhost:6006/story/button--primary",code_path: "src/components/Button.tsx",threshold: 80,// Score below which fix is generated (default: 80)})
What it checks: spacing, color tokens, typography, borders, border-radius, interactive states.
What it returns: 0–100 parity score, ranked mismatches with consequences, pattern detection (e.g. "AI-generated code signature"), and a patch-ready git diff.
flag_stale_mappings — ships now
Cross-references Code Connect mappings in your repo against Figma version history and git blame. Surfaces components that have drifted silently, ranked by blast radius and days since divergence.
flag_stale_mappings({file_id: "abc123",repo_root: ".",// Path to your repo root})
Reads from .figma/code-connect.json in your repo root.
generate_sync_patch — ships now
Generates a surgical patch for a specific component — token substitutions, prop corrections, missing state stubs. Output as git diff, JSX corrections, or CSS delta.
generate_sync_patch({file_id: "abc123",node_id: "123:456",code_path: "src/components/Button.tsx",format: "diff",// "diff" | "jsx" | "css"})
audit_state_coverage — v0.2
Checks whether every interactive state defined in a Figma component set (hover, focus, disabled, error, loading) exists in code. Flags WCAG 2.4.7 risk for missing focus rings.
check_responsive_parity — v0.2
Renders at 375/768/1280/1920px and catches overflow, collapsed containers, and flex direction errors.
check_theme_parity — v0.2
Runs parity across Figma variable modes — light/dark, brand variants, high-contrast. Catches hardcoded colors that are invisible in light mode but break in dark.
Finding your Figma IDs
File ID: From the URL — figma.com/file/{FILE_ID}/...
Node ID: Right-click a component in Figma → Copy link → extract the node-id parameter. Format: 123:456. Note: the URL uses 123-456 (hyphen) but the API uses 123:456 (colon) — DesignDiff handles the encoding automatically.
How it works
  1. Fetch — Calls the Figma REST API and extracts the full design spec: exact pixel values, token references, and every variant state from the component set.
  2. Render — Launches a headless Playwright browser and renders your component at its real URL. Captures computed CSS — what the browser actually produces after cascade and runtime overrides resolve.
  3. Score — Compares the two. Token violations score highest (they break the entire design system contract). Missing focus states are flagged with WCAG reference. Every mismatch includes the real-world consequence of not fixing it.
  4. Fix — When score is below threshold, generates a patch-ready diff the agent applies in the same response, then re-verifies the score improved.
Configuration
Environment variableRequiredDefaultDescription
FIGMA_API_KEY✓—Figma personal access token
TRANSPORT—stdiostdio or http
PORT—3847HTTP port (when TRANSPORT=http)
HTTP transport
For use with non-stdio MCP clients:
FIGMA_API_KEY=xxx TRANSPORT=http npx designdiff-mcp
# → DesignDiff MCP v0.2 running at http://localhost:3847/mcp
Health check: GET /health
Development
git clone https://github.com/designdiff/designdiff-mcp
cd designdiff-mcp
npm install
npx playwright install chromium
npm run build
FIGMA_API_KEY=xxx npm start
Inspect tools interactively:
npm run inspector
This opens the MCP Inspector UI where you can call tools directly.
Roadmap
StageWhat ships
v0.1 — NowRendered parity check · token compliance · patch-ready diffs
v0.2State coverage · responsive parity · theme parity · Storybook adapter
v1.0Unified quality score · CI gate · score history · Slack alerts
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE.
By Mathew Graham
About
DesignDiff verifies that AI-generated interfaces match your design system before they reach production.
designdiff.netlify.app/
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