authoring-excalidraw-files

name	authoring-excalidraw-files
description	Generate architecture diagrams as .excalidraw files. Use when the user asks to create architecture diagrams, system diagrams, visualize codebase structure, infrastructure diagrams, or generate excalidraw files.

Excalidraw Architecture Diagram Generator

Generate architecture diagrams as .excalidraw files from codebase analysis or user specifications.

---

Prerequisites

• No prerequisites - generates raw JSON
• For visual inspection: Open .excalidraw files in excalidraw.com or VS Code extension

---

Quick Start

User asks:

"Generate an architecture diagram for this project"
"Create an excalidraw diagram of the system"
"Visualize this codebase structure"
"Draw the infrastructure architecture"

Claude will:

1. Analyze the codebase (any language/framework)
2. Identify components, services, databases, APIs
3. Map relationships and data flows
4. Generate valid .excalidraw JSON
5. Validate the structure
6. User opens in excalidraw.com or VS Code for visual inspection

---

Critical Rules

1. NEVER Use Diamond Shapes

Diamond arrow connections are broken in raw Excalidraw JSON. Use styled rectangles instead:

Semantic Meaning	Rectangle Style
Orchestrator/Hub	Coral (#ffa8a8/#c92a2a) + strokeWidth: 3
Decision Point	Orange (#ffd8a8/#e8590c) + dashed stroke

2. Labels Require TWO Elements

The label property does NOT work in raw JSON. Every labeled shape needs:

// 1. Shape with boundElements reference
{
  "id": "my-box",
  "type": "rectangle",
  "boundElements": [{ "type": "text", "id": "my-box-text" }]
}

// 2. Separate text element with containerId
{
  "id": "my-box-text",
  "type": "text",
  "containerId": "my-box",
  "text": "My Label"
}

3. Elbow Arrows Need Three Properties

For 90-degree corners (not curved):

{
  "type": "arrow",
  "roughness": 0,        // Clean lines
  "roundness": null,     // Sharp corners
  "elbowed": true        // 90-degree mode
}

4. Arrow Position at Shape Edge

Arrows must start/end at shape edges, not centers:

Edge	Formula
Top	(x + width/2, y)
Bottom	(x + width/2, y + height)
Left	(x, y + height/2)
Right	(x + width, y + height/2)

5. Arrow width/height = Bounding Box

points = [[0, 0], [-440, 0], [-440, 70]]
width = 440   // max(abs(point[0]))
height = 70   // max(abs(point[1]))

---

Minimal Working Example

Two boxes connected by an arrow (copy and adapt for any diagram):

{
  "type": "excalidraw",
  "version": 2,
  "source": "claude-code-excalidraw-skill",
  "elements": [
    {
      "id": "box-a",
      "type": "rectangle",
      "x": 100,
      "y": 100,
      "width": 160,
      "height": 80,
      "angle": 0,
      "strokeColor": "#1971c2",
      "backgroundColor": "#a5d8ff",
      "fillStyle": "solid",
      "strokeWidth" 
       
       
       
       
       
          
       
       
       
       
            
       
       
       
    
    
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
    
    
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
          
       
       
       
       
            
       
       
       
    
    
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
    
    
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
       
          
       
       
       
       
       
       
    
  
   
     
     
  
   

Key structure notes:

• Each labeled shape needs TWO elements (shape + text with containerId)
• Arrow x,y is at source edge: (100 + 160/2, 100 + 80) = (180, 180)
• Arrow height matches the vertical distance: 280 - 180 = 100
• Elbow arrows: roughness: 0, roundness: null, elbowed: true

---

Workflow

Step 1: Analyze Codebase

Discover components by looking for:

Codebase Type	What to Look For
Monorepo	packages/*/package.json, workspace configs
Microservices	docker-compose.yml, k8s manifests
IaC	Terraform/Pulumi resource definitions
Backend API	Route definitions, controllers, DB models
Frontend	Component hierarchy, API calls

Use tools:

• Glob for **/package.json, **/Dockerfile, **/*.tf
• Grep for app.get, @Controller, CREATE TABLE
• Read for README, config files, entry points

Step 2: Plan Layout

Vertical flow (most common):

Row 1: Users/Entry points (y: 100)
Row 2: Frontend/Gateway (y: 250)
Row 3: Orchestration (y: 400)
Row 4: Services (y: 550)
Row 5: Data layer (y: 700)

Columns: x = 100, 300, 500, 700, 900
Element size: 160-200px x 80-90px

Step 3: Generate Elements

For each component:

1. Create shape with unique id
2. Add boundElements referencing text
3. Create text with containerId
4. Choose color based on type (see references/colors.md)

Step 4: Add Connections

For each relationship:

1. Calculate source edge point
2. Calculate target edge point
3. Determine routing pattern
4. Create arrow with points array
5. Set width/height from bounding box

See references/arrows.md for routing patterns.

Step 5: Validate

Run validation script before finalizing:

uv run scripts/validate_excalidraw.py diagram.excalidraw

Checks performed:

• Valid JSON structure
• boundElements/containerId pairs match
• No duplicate IDs
• No diamond shapes
• Elbow arrows have required properties
• Arrow width/height matches points

Step 6: Visual Inspection and Iterate

Open the .excalidraw file for visual inspection:

• Web: Drag file to excalidraw.com
• VS Code: Install "Excalidraw" extension and open file

Note: Claude cannot see the visual output. The user must review the diagram and report any issues.

If the user reports issues:

1. Identify the problem element from their description
2. Fix the JSON
3. Re-validate
4. Ask user to re-inspect
5. Repeat until correct

---

Validation Checklist

Before writing file:

• Every shape with label has boundElements + text element
• Text elements have containerId matching shape
• Multi-point arrows have elbowed: true, roundness: null, roughness: 0
• Arrow x,y = source shape edge point
• Arrow final point offset reaches target edge
• Arrow width/height = bounding box of points
• No diamond shapes
• No duplicate IDs
• File is valid JSON

---

Common Issues

Issue	Fix
Labels don't appear	Use TWO elements (shape + text), not label property
Arrows curved	Add elbowed: true, roundness: null, roughness: 0
Arrows floating	Calculate x,y from shape edge, not center
Arrows overlapping	Stagger start positions across edge
Arrows clipped	Set width/height to bounding box of points

---

Reference Files

File	Contents
references/schema.md	JSON format, element types, text bindings, frames
references/arrows.md	Routing algorithm, patterns, bindings, staggering
references/colors.md	Default, AWS, Azure, GCP, Kubernetes palettes

---

Scripts

Script	Purpose
scripts/validate_excalidraw.py	Validate JSON structure before saving

Usage:

# Validate
uv run scripts/validate_excalidraw.py diagram.excalidraw

# Validate with verbose arrow checks
uv run scripts/validate_excalidraw.py diagram.excalidraw --verbose

# Output as JSON
uv run scripts/validate_excalidraw.py diagram.excalidraw --json

---

Output

• Location: docs/architecture/ or user-specified
• Filename: Descriptive, e.g., system-architecture.excalidraw
• Testing: Open in https://excalidraw.com or VS Code extension