---
name: baoyu-diagram
description: Create professional, dark-themed SVG diagrams of any type — architecture, flowcharts, sequence, structural, mind maps, timelines, and more.
---

# 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

| Type | When to Use | Key Characteristics |
|------|-------------|-------------------|
| **Architecture** | System components & relationships | Grouped boxes, connection arrows, region boundaries |
| **Flowchart** | Decision logic, process steps | Diamond decisions, rounded step boxes, directional flow |
| **Sequence** | Time-ordered interactions between actors | Vertical lifelines, horizontal messages, activation bars |
| **Structural** | Class diagrams, ER diagrams, org charts | Compartmented boxes, typed relationships (inheritance, composition) |
| **Mind Map** | Brainstorming, topic exploration | Central node, radiating branches, organic layout |
| **Timeline** | Chronological events | Horizontal/vertical axis, event markers, period spans |
| **Illustrative** | Conceptual explanations, comparisons | Free-form layout, icons, annotations, visual metaphors |
| **State Machine** | State transitions, lifecycle | Rounded state nodes, labeled transitions, start/end markers |
| **Data Flow** | Data transformation pipelines | Process bubbles, data stores, external entities |

## Design System

### Color Palette

Semantic colors for component categories:

| Category | Fill (rgba) | Stroke | Use For |
|----------|-------------|--------|---------|
| Primary | `rgba(8, 51, 68, 0.4)` | `#22d3ee` (cyan) | Frontend, user-facing, inputs |
| Secondary | `rgba(6, 78, 59, 0.4)` | `#34d399` (emerald) | Backend, services, processing |
| Tertiary | `rgba(76, 29, 149, 0.4)` | `#a78bfa` (violet) | Database, storage, persistence |
| Accent | `rgba(120, 53, 15, 0.3)` | `#fbbf24` (amber) | Cloud, infrastructure, regions |
| Alert | `rgba(136, 19, 55, 0.4)` | `#fb7185` (rose) | Security, errors, warnings |
| Connector | `rgba(251, 146, 60, 0.3)` | `#fb923c` (orange) | Buses, queues, middleware |
| Neutral | `rgba(30, 41, 59, 0.5)` | `#94a3b8` (slate) | External, generic, unknown |
| Highlight | `rgba(59, 130, 246, 0.3)` | `#60a5fa` (blue) | Active state, focus, current step |

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:

```svg
<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:
```svg
<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):**
```svg
<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:**
```svg
<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):**
```svg
<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:
```svg
<!-- 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):**
```svg
<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):**
```svg
<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:**
```svg
<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:**
```svg
<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:**
```svg
<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 data flow. Group related services in region boundaries. Use buses/connectors between layers. Place databases at the bottom or right.

### Flowcharts
→ Read `{baseDir}/references/flowchart.md`

Key points: top-to-bottom primary flow. Diamonds for decisions with Yes/No labels on exit arrows. Rounded rectangles for start/end. Use the Highlight color for the happy path.

### Sequence Diagrams
→ Read `{baseDir}/references/sequence.md`

Key points: actors as boxes at top, vertical dashed lifelines, horizontal arrows for messages (solid=sync, dashed=return). Time flows downward. Activation bars show processing. Number messages if complex.

### Structural Diagrams
→ Read `{baseDir}/references/structural.md`

Key points: compartmented boxes (name / attributes / methods for class diagrams). Relationship lines: solid with filled diamond=composition, solid with empty diamond=aggregation, dashed arrow=dependency, solid triangle=inheritance.

### Mind Maps
Free-form radiating layout from a central concept. Use organic curves (`<path>` with cubic beziers) for branches. Vary branch colors using the palette. Larger font for central node, decreasing as you go outward.

### Timelines
Horizontal or vertical axis line. Event markers as circles or diamonds on the axis. Description text offset to alternating sides to avoid overlap. Use color to categorize event types.

### State Machines
Rounded-rect states with double-border for composite states. Filled circle for initial state, bullseye for final state. Curved arrows for self-transitions. Label all transitions with `event [guard] / action` format.

## Output Rules

1. Output a **single `.svg` file** — no external dependencies except the Google Fonts import
2. Set `viewBox` to fit all content with 30px padding; do NOT set fixed `width`/`height` attributes (let the SVG scale responsively)
3. Include `xmlns="http://www.w3.org/2000/svg"` on the root `<svg>` element
4. Put all `<style>`, `<defs>`, markers, and patterns at the top of the SVG
5. Use `text-anchor="middle"` for centered labels; ensure text doesn't overflow boxes
6. **Chinese text support:** When labels contain Chinese characters, use `font-family: 'JetBrains Mono', 'Noto Sans SC', 'PingFang SC', sans-serif'` and increase box widths — CJK characters are wider
7. **Save location:** If the input is a file, save to `{inputFileDir}/diagram/`. Otherwise save to `{projectDir}/diagram/{topic-slug}/`. Create the directory if it doesn't exist

## Script

Determine this SKILL.md file's directory path as `{baseDir}`. Script path: `{baseDir}/scripts/main.ts`.

Resolve `${BUN_X}` runtime: if `bun` installed → `bun`; if `npx` available → `npx -y bun`; else suggest installing bun.

### SVG → @2x PNG

After saving the SVG, convert it to a @2x PNG:

```bash
${BUN_X} {baseDir}/scripts/main.ts <svg-path> [options]
```

Options:
- `-s, --scale <n>` — Scale factor (default: 2)
- `-o, --output <path>` — Custom output path (default: `<input>@2x.png`)
- `--json` — JSON output

## Process

1. Identify the diagram type from the user's request
2. Read the relevant reference file if one exists for that type
3. Plan the layout: list all components, determine grouping and flow direction, calculate positions
4. Write the SVG following the layering order above
5. Verify spacing rules — no overlaps, legends outside boundaries, viewBox large enough
6. Save the SVG file
7. Run `${BUN_X} {baseDir}/scripts/main.ts <svg-path>` to generate @2x PNG
8. Present both files to the user