Mermaid Render Plugin

The Mermaid Render plugin gives the agent a render_mermaid tool that turns Mermaid diagram source into an SVG or PNG image file on disk. It drives a headless Chromium-family browser to render the diagram with mermaid.js.

Configuration

plugins:
  - module: codumentor.plugins.mermaid_render
    class: MermaidRenderPlugin
    args:
      enabled: true
      target_agents: "main"
      timeout: 30
      # mermaid_js_url: "file:///opt/mermaid/mermaid.min.js"  # for offline use

Parameters

• enabled (optional): Whether the plugin is active (default: true)
• target_agents (optional): Which agents receive the tool — "main", "subagent", or "all" (default: "main")
• timeout (optional): Per-render timeout in seconds (default: 30)
• mermaid_js_url (optional): Where to load mermaid.js from inside the browser (default: the jsDelivr CDN mermaid@11). Point it at a file:// path or self-hosted copy for offline/restricted networks.
• default_theme (optional): "default", "dark", "forest", "neutral", or "base" (default: "default")
• default_background (optional): CSS background colour; "transparent" is meaningful only for PNG (default: "white")

Tool Reference

Tool	Description
render_mermaid	Render Mermaid source to output_path. Optional format (svg/png, defaults from the path's extension), theme, and background. Returns the absolute path plus metadata (format, size, theme). Parent directories are created as needed.

Notes

• Requirements: a Chromium-family browser (Chrome, Edge, or Chromium) installed on the host. Availability is checked at startup; if it's missing, the first call returns an error with install instructions. Install with pip install playwright && playwright install chromium.
• Rendering uses Mermaid's securityLevel: 'strict' to mitigate diagram-based XSS.
• background: "transparent" with format: "png" produces a PNG with an alpha channel.
• Users can enable/disable the plugin for themselves via a settings widget.