| name | beautiful-mermaid |
| description | Render Mermaid diagrams as SVG and PNG using the Beautiful Mermaid library. Use when the user asks to render a Mermaid diagram. |
Beautiful Mermaid Diagram Rendering
Render Mermaid diagrams as SVG and PNG images using the Beautiful Mermaid library.
Dependencies
This skill requires the agent-browser skill for PNG rendering. Load it before proceeding with PNG capture.
Flowchart Direction
ALWAYS use TD (top-down) for flowcharts. Start every flowchart with graph TD.
Do NOT use LR, RL, or BT directions.
Supported Diagram Types
- Flowchart - Process flows, decision trees, CI/CD pipelines (always use
graph TD)
- Sequence - API calls, OAuth flows, database transactions
- State - State machines, connection lifecycles
- Class - UML class diagrams, design patterns
- Entity-Relationship - Database schemas, data models
Available Themes
Default, Dracula, Solarized, Zinc Dark, Tokyo Night, Tokyo Night Storm, Tokyo Night Light, Catppuccin Latte, Nord, Nord Light, GitHub Dark, GitHub Light, One Dark.
If no theme is specified, use default.
Common Syntax Patterns
Flowchart Edge Labels
Use pipe syntax for edge labels:
A -->|label| B
A ---|label| B
Avoid space-dash syntax which can cause incomplete renders:
A -- label --> B # May cause issues
Node Labels with Special Characters
Wrap labels containing special characters in quotes:
A["Label with (parens)"]
B["Label with / slash"]
Workflow
Step 1: Generate or Validate Mermaid Code
If the user provides a description rather than code, generate valid Mermaid syntax. Consult references/mermaid-syntax.md for full syntax details.
Step 2: Render SVG
Run the rendering script to produce an SVG file:
npx tsx skills/diagrams/beautiful-mermaid/scripts/render.ts --code "graph TD
A-->B" --output svg/diagram --theme default
Or from a file:
npx tsx skills/diagrams/beautiful-mermaid/scripts/render.ts --input diagram.mmd --output svg/diagram --theme tokyo-night
Important:
- The script path is
skills/diagrams/beautiful-mermaid/scripts/render.ts
- Output files go to the
svg/ directory
- Mermaid code uses NEWLINES between statements, not semicolons
This produces <output>.svg in the current working directory.
Step 3: Create HTML Wrapper (Optional - for PNG only)
Run the HTML wrapper script to prepare for screenshot:
npx tsx skills/diagrams/beautiful-mermaid/scripts/create-html.ts --svg svg/diagram.svg --output svg/diagram.html
This creates a minimal HTML file that displays the SVG with proper padding and background.
Step 4: Capture High-Resolution PNG with agent-browser
Use the agent-browser CLI to capture a high-quality screenshot. Refer to the agent-browser skill for full CLI documentation.
agent-browser set viewport 3840 2160
agent-browser open "file://$(pwd)/diagram.html"
agent-browser wait 1000
agent-browser screenshot --full diagram.png
agent-browser close
For even higher resolution on complex diagrams, increase the viewport further or use the --padding option when creating the HTML wrapper to give the diagram more space.
Step 5: Clean Up Intermediary Files
After rendering, remove all intermediary files. Only the final .svg and .png should remain.
Files to clean up:
- The HTML wrapper file (e.g.,
diagram.html)
- Any temporary
.mmd files created to hold diagram code
- Any other files created during the rendering process
rm diagram.html
If a temporary .mmd file was created, remove it as well.
Output
Both outputs are always produced:
- SVG: Vector format, infinitely scalable, small file size
- PNG: High-resolution raster, captured at 4K (3840×2160) viewport with minimum 1200px diagram width
Files are saved to the current working directory unless the user explicitly specifies a different path.
Theme Selection Guide
| Theme | Background | Best For |
|---|
| default | Light grey | General use |
| dracula | Dark purple | Dark mode preference |
| tokyo-night | Dark blue | Modern dark aesthetic |
| tokyo-night-storm | Darker blue | Higher contrast |
| nord | Dark arctic | Muted, calm visuals |
| nord-light | Light arctic | Light mode with soft tones |
| github-dark | GitHub dark | Matches GitHub UI |
| github-light | GitHub light | Matches GitHub UI |
| catppuccin-latte | Warm light | Soft pastel aesthetic |
| solarized | Tan/cream | Solarized colour scheme |
| one-dark | Atom dark | Atom editor aesthetic |
| zinc-dark | Neutral dark | Minimal, no colour bias |
Troubleshooting
Theme not applied
Check the render script output for the bg and fg values, or inspect the SVG's opening tag for --bg and --fg CSS custom properties.
Diagram appears cut off or incomplete
- Check edge label syntax — use
-->|label| pipe notation, not -- label -->
- Verify all node IDs are unique
- Check for unclosed brackets in node labels
Render produces empty or malformed SVG
- Validate Mermaid syntax at https://mermaid.live before rendering
- Check for special characters that need escaping (wrap in quotes)
- Ensure flowchart direction is specified (
graph TD, graph LR, etc.)
