baoyu-diagram

# 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="