Diagram Generator

Create professional SVG diagrams across multiple diagram types. All output is a single self-contained .svg file with embedded styles and fonts.

Supported Diagram Types

Design System

Color Palette

Semantic colors for component categories:

For flowcharts and sequence diagrams, assign colors by role (actor, decision, process) rather than by technology.

Typography

Use embedded SVG @font-face or system monospace fallback:

<style>
  @import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;500;600;700&amp;display=swap');
  text { font-family: 'JetBrains Mono', 'SF Mono', 'Cascadia Code', monospace; }
</style>

Font sizes by role:

• Title: 16px, weight 700
• Component name: 11-12px, weight 600
• Sublabel / description: 9px, weight 400, color #94a3b8
• Annotation / note: 8px, weight 400
• Tiny label (on arrows): 7-8px

Core Visual Elements

Background: #0f172a (slate-900) with subtle grid:

<defs>
  <pattern id="grid" width="40" height="40" patternUnits="userSpaceOnUse">
    <path d="M 40 0 L 0 0 0 40" fill="none" stroke="#1e293b" stroke-width="0.5"/>
  </pattern>
</defs>
<rect width="100%" height="100%" fill="#0f172a"/>
<rect width="100%" height="100%" fill="url(#grid)"/>

Arrowhead marker (standard):

<marker id="arrow" markerWidth="10" markerHeight="7" refX="9" refY="3.5" orient="auto">
  <polygon points="0 0, 10 3.5, 0 7" fill="#64748b"/>
</marker>

Arrowhead marker (colored) — create per-color as needed:

<marker id="arrow-cyan" markerWidth="10" markerHeight="7" refX="9" refY="3.5" orient="auto">
  <polygon points="0 0, 10 3.5, 0 7" fill="#22d3ee"/>
</marker>

Open arrowhead (for async/return messages):

<marker id="arrow-open" markerWidth="10" markerHeight="7" refX="9" refY="3.5" orient="auto">
  <polyline points="0 0, 10 3.5, 0 7" fill="none" stroke="#64748b" stroke-width="1.5"/>
</marker>

SVG Structure & Layering

Draw elements in this order to get correct z-ordering (SVG paints back-to-front):

1. Background fill + grid pattern
2. Region/group boundaries (dashed outlines)
3. Connection arrows and lines
4. Opaque masking rects (same position as component boxes, fill="#0f172a")
5. Component boxes (semi-transparent fill + stroke)
6. Text labels
7. Legend (bottom-right or bottom area, outside all boundaries)
8. Title block (top-left)

The opaque masking rect trick is essential — semi-transparent component fills will show arrows underneath without it:

<!-- Mask layer: opaque background to hide arrows -->
<rect x="100" y="100" width="160" height="60" rx="6" fill="#0f172a"/>
<!-- Visual layer: styled component -->
<rect x="100" y="100" width="160" height="60" rx="6" fill="rgba(8,51,68,0.4)" stroke="#22d3ee" stroke-width="1.5"/>
<text x="180" y="125" fill="white" font-size="11" font-weight="600" text-anchor="middle">API Gateway</text>
<text x="180" y="141" fill="#94a3b8" font-size="9" text-anchor="middle">Kong / Nginx</text>

Spacing Rules

These prevent overlapping — follow them strictly:

• Component box height: 50-70px (standard), 80-120px (large/complex)
• Minimum gap between components: 40px vertical, 30px horizontal
• Arrow label clearance: 10px from any box edge
• Region boundary padding: 20px inside edges around contained components
• Legend placement: At least 20px below the lowest diagram element
• Title block: 20px from top-left, outside diagram content area
• viewBox: Always extend to fit all content + 30px padding on all sides

Component Patterns

Standard box (service/process):

<rect x="X" y="Y" width="160" height="60" rx="6" fill="#0f172a"/>
<rect x="X" y="Y" width="160" height="60" rx="6" fill="FILL" stroke="STROKE" stroke-width="1.5"/>
<text x="CX" y="Y+24" fill="white" font-size="11" font-weight="600" text-anchor="middle">Name</text>
<text x="CX" y="Y+40" fill="#94a3b8" font-size="9" text-anchor="middle">description</text>

Decision diamond (flowchart):

<g transform="translate(CX, CY)">
  <polygon points="0,-35 50,0 0,35 -50,0" fill="#0f172a"/>
  <polygon points="0,-35 50,0 0,35 -50,0" fill="rgba(120,53,15,0.3)" stroke="#fbbf24" stroke-width="1.5"/>
  <text y="4" fill="white" font-size="10" font-weight="600" text-anchor="middle">Condition?</text>
</g>

Database cylinder:

<g transform="translate(X, Y)">
  <rect x="0" y="10" width="120" height="50" rx="2" fill="#0f172a"/>
  <ellipse cx="60" cy="10" rx="60" ry="12" fill="#0f172a"/>
  <ellipse cx="60" cy="60" rx="60" ry="12" fill="#0f172a"/>
  <rect x="0" y="10" width="120" height="50" fill="rgba(76,29,149,0.4)"/>
  <ellipse cx="60" cy="10" rx="60" ry="12" fill="rgba(76,29,149,0.4)" stroke="#a78bfa" stroke-width="1.5"/>
  <ellipse cx="60" cy="60" rx="60" ry="12" fill="rgba(76,29,149,0.4)" stroke="#a78bfa" stroke-width="1.5"/>
  <line x1="0" y1="10" x2="0" y2="60" stroke="#a78bfa" stroke-width="1.5"/>
  <line x1="120" y1="10" x2="120" y2="60" stroke="#a78bfa" stroke-width="1.5"/>
  <text x="60" y="40" fill="white" font-size="11" font-weight="600" text-anchor="middle">PostgreSQL</text>
</g>

Region boundary:

<rect x="X" y="Y" width="W" height="H" rx="12" fill="none" stroke="#fbbf24" stroke-width="1" stroke-dasharray="8,4"/>
<text x="X+12" y="Y+16" fill="#fbbf24" font-size="9" font-weight="600">AWS us-east-1</text>

Security group:

<rect x="X" y="Y" width="W" height="H" rx="8" fill="none" stroke="#fb7185" stroke-width="1" stroke-dasharray="4,4"/>
<text x="X+10" y="Y+14" fill="#fb7185" font-size="8" font-weight="500">VPC / Security Group</text>

Type-Specific Layout Guidance

Determine this SKILL.md file's directory path as {baseDir}. Read the reference file for the specific diagram type before starting layout. Reference files are located at {baseDir}/references/ and contain detailed layout algorithms and examples.

Architecture Diagrams

→ Read {baseDir}/references/architecture.md

Key points: left-to-right or top-to-bottom da