Excalidraw Diagram Generator

Create Excalidraw diagrams from text content with multiple output formats compatible with Obsidian's Excalidraw plugin.

Output Modes

The user must explicitly request a diagram. Do not generate or save files unless the user asks for one.

If the mode is ambiguous, ask the user which format they want.

Process

1. Confirm output mode with the user if ambiguous
2. Analyze content - identify concepts, relationships, hierarchy
3. Choose diagram type based on content structure
4. Generate Excalidraw JSON following design rules below
5. Output in correct format based on mode
6. Ask the user for the save path and filename before writing
7. Check if file exists at the target path. If it does, ask before overwriting
8. Save the file only after user confirmation

Output Formats

Mode 1: Obsidian Format (Default)

This format wraps the JSON in Markdown so Obsidian's Excalidraw plugin opens it directly:

---
excalidraw-plugin: parsed
tags: [excalidraw]
---

==⚠  Switch to EXCALIDRAW VIEW in the MORE OPTIONS menu of this document. ⚠==
You can decompress Drawing data with the command palette: 'Decompress current Excalidraw file'. For more info check in plugin settings under 'Saving'

# Excalidraw Data

## Text Elements
%%

## Drawing
```json
{"type":"excalidraw","version":2,"source":"https://github.com/zsviczian/obsidian-excalidraw-plugin","elements":[...],"appState":{"gridSize":null,"viewBackgroundColor":"#ffffff"},"files":{}}

%%

**Critical formatting rules:**
- Frontmatter MUST include `tags: [excalidraw]`
- The warning message must be complete
- JSON must be inside a ```json code block
- Text Elements section stays empty (just `%%`)
- Source must be `"https://github.com/zsviczian/obsidian-excalidraw-plugin"` for Obsidian mode

### Mode 2: Standard Excalidraw Format

Pure JSON for excalidraw.com:

```json
{
  "type": "excalidraw",
  "version": 2,
  "source": "https://excalidraw.com",
  "elements": [...],
  "appState": { "gridSize": null, "viewBackgroundColor": "#ffffff" },
  "files": {}
}

Design Rules

Typography

• All text elements must use "fontFamily": 5 (Excalifont - hand-drawn style)
• Font sizes:
  • Titles: 24-28px (minimum 20px)
  • Subtitles: 18-20px
  • Body/labels: 16-18px (minimum 16px)
  • Annotations: 14px (use sparingly)
• Never use font size below 14px - unreadable at normal zoom
• Line height: "lineHeight": 1.25 for all text
• Text alignment: "textAlign": "center", "verticalAlign": "middle" for labels

Layout

• Canvas range: Keep all elements within 0-1200 x 0-800 pixels
• Minimum shape size: Rectangles/ellipses with text should be at least 120x60px
• Element spacing: Minimum 20-30px between elements to prevent overlap
• Padding: Leave 50-80px padding around all edges
• Grid: Place elements on 20px grid for alignment

Color Palette

Shape fill colors (backgroundColor, fillStyle: "solid"):

Text colors (strokeColor):

Contrast rules:

• White background text: minimum #757575 lightness
• Light fills: use dark variants (e.g., light green fill → #15803d text)
• Avoid light gray text (#b0b0b0, #999) on white

Styling

• Roughness: 1 (artist style) for hand-drawn look, or 0 (architect) for clean diagrams
• Stroke width: 2 (normal) for most elements
• Roundness: { "type": 3 } for rounded corners on rectangles
• Opacity: 100 for most elements, 30-50 for background layers

Diagram Types

Choose the appropriate visualization based on content:

JSON Structure

Root Structure

{
  "type": "excalidraw",
  "version": 2,
  "source": "https://github.com/zsviczian/obsidian-excalidraw-plugin",
  "elements": [...],
  "appState": {
    "gridSize": null,
    "viewBackgroundColor": "#ffffff"
  },
  "files": {}
}

Element Template

All elements require these fields:

{
  "id": "unique-id-string",
  "type": "rectangle|ellipse|text|arrow|diamond|line",
  "x": 100,
  "y": 100,
  "width": 200,
  "height": 50,
  "angle": 0,
  "strokeColor": "#1e1e1e",
  "backgroundColor": "transparent",
  "fillStyle": "solid",
  "strokeWidth": 2,
  "strokeStyle": "solid",
  "roughness": 1,
  "opacity": 100,
  "groupIds": [],
  "roundness": { "type": 3 },
  "seed": 123456789,
  "version": 1,
  "isDeleted": false,
  "boundElements": null,
  "updated": 1,
  "link": null,
  "locked": false
}

Important:

• Use "boundElements": null (not [])
• Use "updated": 1 (not timestamps)
• Do NOT include frameId, index, versionNonce, or rawText

Text Element (additional fields)

{
  "type": "text",
  "text": "Label Text",
  "fontSize": 20,
  "fontFamily": 5,
  "textAlign": "center",
  "verticalAlign": "middle",
  "containerId": null,
  "originalText": "Label Text",
  "autoResize": true,
  "lineHeight": 1.25
}

Arrow Element (additional fields)

{
  "type": "arrow",
  "points": [[0, 0], [200, 0]],
  "startBinding": null,
  "endBinding": null,
  "startArrowhead": null,
  "endArrowhead": "arrow",
  "elbowed": false
}

For arrows connecting shapes, use startBinding and endBinding:

{
  "startBinding": { "elementId": "shape-id-1", "focus": 0, "gap": 1, "fixedPoint": null },
  "endBinding": { "elementId": "shape-id-2", "focus": 0, "gap": 1, "fixedPoint": null }
}

Add the arrow to each shape's boundElements:

{
  "boundElements": [
    { "id": "arrow-id", "type": "arrow" }
  ]
}

Text Centering Calculation

Text elements use left-edge x coordinate. To center text:

estimatedWidth = text.length * fontSize * 0.5  (use * 1.0 for CJK characters)
x = centerX - estimatedWidth / 2

Example: Text "Hello" (5 chars, 20px) centered at x=300:

• estimatedWidth = 5 * 20 * 0.5 = 50
• x = 300 - 25 = 275

Common Patterns

Architecture Diagram

• Rectangles for services/components
• Color-code by layer (frontend=blue, middleware=purple, backend=green)
• Arrows for data flow
• Group related components visually

Flowchart

• Rectangles for process steps
• Diamonds for decision points
• Arrows showing flow direction
• Top-to-bottom or left-to-right layout

Mind Map

• Central topic in middle
• Branches radiating outward
• Use consistent colors per branch
• Sub-branches connect to main branches

File Naming

Suggest descriptive filenames based on content, but always confirm with the user before saving:

Before writing any file:

• Confirm the full save path and filename with the user
• If a file already exists at that path, warn the user and ask before overwriting
• Never write files silently or to assumed default paths

Example User Messages

• "Create an Excalidraw diagram of our microservices architecture"
• "Draw a flowchart showing the CI/CD pipeline"
• "Make a mind map of machine learning concepts"
• "Generate a standard excalidraw file for this workflow" (forces .excalidraw output)

Implementation Checklist

When generating a diagram:

1. Confirm output mode with user (Obsidian or Standard)
2. Analyze content and select diagram type
3. Plan layout (positions, connections, groupings)
4. Generate elements with:
   • Unique IDs for each element
   • "fontFamily": 5 for all text
   • Proper colors from palette
   • Correct bindings for arrows and labels
5. Validate JSON is syntactically correct
6. Wrap in appropriate output format
7. Confirm save path and filename with user
8. Check for existing file at target path (warn if exists)
9. Save only after user confirmation
10. Report file path and usage instructions to user