excalidraw by ooiyeefei

---
name: excalidraw
description: Generate architecture diagrams as .excalidraw files from codebase analysis, with optional PNG/SVG export. Use when the user asks to create architecture diagrams, system diagrams, visualize codebase structure, generate excalidraw files, export excalidraw diagrams to PNG or SVG, or convert .excalidraw files to image formats.
---

# Excalidraw Diagram Generator

Generate architecture diagrams as `.excalidraw` files directly from codebase analysis, with optional export to PNG and SVG.

---

## Quick Start

**User just asks:**
```
"Generate an architecture diagram for this project"
"Create an excalidraw diagram of the system"
"Visualize this codebase as an excalidraw file"
```

**Claude Code 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 with dynamic IDs and labels
5. Optionally export to PNG and/or SVG using Playwright

**No prerequisites:** Works without existing diagrams, Terraform, or specific file types.

---

## 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:

```json
// 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):

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

### 4. Arrow Edge Calculations

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)` |

**Detailed arrow routing:** See `references/arrows.md`

---

## Element Types

| Type | Use For |
|------|---------|
| `rectangle` | Services, databases, containers, orchestrators |
| `ellipse` | Users, external systems, start/end points |
| `text` | Labels inside shapes, titles, annotations |
| `arrow` | Data flow, connections, dependencies |
| `line` | Grouping boundaries, separators |

**Full JSON format:** See `references/json-format.md`

---

## 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` → `**/package.json`, `**/Dockerfile`, `**/*.tf`
- `Grep` → `app.get`, `@Controller`, `CREATE TABLE`
- `Read` → 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: 230)
Row 3: Orchestration (y: 380)
Row 4: Services (y: 530)
Row 5: Data layer (y: 680)

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

**Other patterns:** See `references/examples.md`

### 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

**Color palettes:** See `references/colors.md`

### Step 4: Add Connections

For each relationship:
1. Calculate source edge point
2. Plan elbow route (avoid overlaps)
3. Create arrow with `points` array
4. Match stroke color to destination type

**Arrow patterns:** See `references/arrows.md`

### Step 5: Add Grouping (Optional)

For logical groupings:
- Large transparent rectangle with `strokeStyle: "dashed"`
- Standalone text label at top-left

### Step 6: Validate and Write

Run validation before writing. Save to `docs/` or user-specified path.

**Validation checklist:** See `references/validation.md`

### Step 7: Export to PNG/SVG (Optional)

After writing the `.excalidraw` file, ask the user if they want PNG, SVG, or both exports.

Uses Playwright MCP tools and `@excalidraw/utils` to programmatically render the diagram — no manual upload to excalidraw.com needed.

**Requires:** Playwright MCP tools (`browser_navigate`, `browser_run_code`, `browser_close`).

**Full export procedure:** See `references/export.md`

---

## Quick Arrow Reference

**Straight down:**
```json
{ "points": [[0, 0], [0, 110]], "x": 590, "y": 290 }
```

**L-shape (left then down):**
```json
{ "points": [[0, 0], [-325, 0], [-325, 125]], "x": 525, "y": 420 }
```

**U-turn (callback):**
```json
{ "points": [[0, 0], [50, 0], [50, -125], [20, -125]], "x": 710, "y": 440 }
```

**Arrow width/height** = bounding box of points:
```
points [[0,0], [-440,0], [-440,70]] → width=440, height=70
```

**Multiple arrows from same edge** - stagger positions:
```
5 arrows: 20%, 35%, 50%, 65%, 80% across edge width
```

---

## Default Color Palette

| Component | Background | Stroke |
|-----------|------------|--------|
| Frontend | `#a5d8ff` | `#1971c2` |
| Backend/API | `#d0bfff` | `#7048e8` |
| Database | `#b2f2bb` | `#2f9e44` |
| Storage | `#ffec99` | `#f08c00` |
| AI/ML | `#e599f7` | `#9c36b5` |
| External APIs | `#ffc9c9` | `#e03131` |
| Orchestration | `#ffa8a8` | `#c92a2a` |
| Message Queue | `#fff3bf` | `#fab005` |
| Cache | `#ffe8cc` | `#fd7e14` |
| Users | `#e7f5ff` | `#1971c2` |

**Cloud-specific palettes:** See `references/colors.md`

---

## Quick 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`
- [ ] Arrow x,y = source shape edge point
- [ ] Arrow final point offset reaches target edge
- [ ] No diamond shapes
- [ ] No duplicate IDs

**Full validation algorithm:** See `references/validation.md`

---

## 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 |

**Detailed bug fixes:** See `references/validation.md`

---

## Reference Files

| File | Contents |
|------|----------|
| `references/json-format.md` | Element types, required properties, text bindings |
| `references/arrows.md` | Routing algorithm, patterns, bindings, staggering |
| `references/colors.md` | Default, AWS, Azure, GCP, K8s palettes |
| `references/examples.md` | Complete JSON examples, layout patterns |
| `references/validation.md` | Checklists, validation algorithm, bug fixes |
| `references/export.md` | PNG/SVG export procedure via Playwright |

---

## Output

- **Location:** `docs/architecture/` or user-specified
- **Filename:** Descriptive, e.g., `system-architecture.excalidraw`
- **Exports (optional):** `system-architecture.svg` and/or `system-architecture.png` in same directory
- **Testing:** Open `.excalidraw` in https://excalidraw.com or VS Code extension; `.svg` and `.png` can be viewed directly or embedded in documentation