drawio

# Draw.io Diagram Skill

Generate draw.io diagrams as native `.drawio` files. Optionally export to PNG, SVG, or PDF with the diagram XML embedded (so the exported file remains editable in draw.io).

## How to create a diagram

1. **Generate draw.io XML** in mxGraphModel format for the requested diagram
2. **Write the XML** to a `.drawio` file in the current working directory using the Write tool
3. **If the user requested an export format** (png, svg, pdf), locate the draw.io CLI (see below), export with `--embed-diagram`, then delete the source `.drawio` file. If the CLI is not found, keep the `.drawio` file and tell the user they can install the draw.io desktop app to enable export, or open the `.drawio` file directly
4. **Open the result** — the exported file if exported, or the `.drawio` file otherwise. If the open command fails, print the file path so the user can open it manually

## Choosing the output format

Check the user's request for a format preference. Examples:

- `/drawio create a flowchart` → `flowchart.drawio`
- `/drawio png flowchart for login` → `login-flow.drawio.png`
- `/drawio svg: ER diagram` → `er-diagram.drawio.svg`
- `/drawio pdf architecture overview` → `architecture-overview.drawio.pdf`

If no format is mentioned, just write the `.drawio` file and open it in draw.io. The user can always ask to export later.

### Supported export formats

| Format | Embed XML  | Notes                                    |
| ------ | ---------- | ---------------------------------------- |
| `png`  | Yes (`-e`) | Viewable everywhere, editable in draw.io |
| `svg`  | Yes (`-e`) | Scalable, editable in draw.io            |
| `pdf`  | Yes (`-e`) | Printable, editable in draw.io           |
| `jpg`  | No         | Lossy, no embedded XML support           |

PNG, SVG, and PDF all support `--embed-diagram` — the exported file contains the full diagram XML, so opening it in draw.io recovers the editable diagram.

## draw.io CLI

The draw.io desktop app includes a command-line interface for exporting.

### Locating the CLI

First, detect the environment, then locate the CLI accordingly:

#### WSL2 (Windows Subsystem for Linux)

WSL2 is detected when `/proc/version` contains `microsoft` or `WSL`:

```bash
grep -qi microsoft /proc/version 2>/dev/null && echo "WSL2"
```

On WSL2, use the Windows draw.io Desktop executable via `/mnt/c/...`:

```bash
DRAWIO_CMD=`/mnt/c/Program Files/draw.io/draw.io.exe`
```

The backtick quoting is required to handle the space in `Program Files` in bash.

If draw.io is installed in a non-default location, check common alternatives:

```bash
# Default install path
`/mnt/c/Program Files/draw.io/draw.io.exe`

# Per-user install (if the above does not exist)
`/mnt/c/Users/$WIN_USER/AppData/Local/Programs/draw.io/draw.io.exe`
```

#### macOS

```bash
/Applications/draw.io.app/Contents/MacOS/draw.io
```

#### Linux (native)

```bash
drawio   # typically on PATH via snap/apt/flatpak
```

#### Windows (native, non-WSL2)

```
"C:\Program Files\draw.io\draw.io.exe"
```

Use `which drawio` (or `where drawio` on Windows) to check if it's on PATH before falling back to the platform-specific path.

### Export command

```bash
drawio -x -f <format> -e -b 10 -o <output> <input.drawio>
```

**WSL2 example:**

```bash
`/mnt/c/Program Files/draw.io/draw.io.exe` -x -f png -e -b 10 -o diagram.drawio.png diagram.drawio
```

Key flags:

- `-x` / `--export`: export mode
- `-f` / `--format`: output format (png, svg, pdf, jpg)
- `-e` / `--embed-diagram`: embed diagram XML in the output (PNG, SVG, PDF only)
- `-o` / `--output`: output file path
- `-b` / `--border`: border width around diagram (default: 0)
- `-t` / `--transparent`: transparent background (PNG only)
- `-s` / `--scale`: scale the diagram size
- `--width` / `--height`: fit into specified dimensions (preserves aspect ratio)
- `-a` / `--all-pages`: export all pages (PDF only)
- `-p` / `--page-index`: select a specific page (1-based)

### Opening the result

| Environment    | Command                                      |
| -------------- | -------------------------------------------- |
| macOS          | `open <file>`                                |
| Linux (native) | `xdg-open <file>`                            |
| WSL2           | `cmd.exe /c start "" "$(wslpath -w <file>)"` |
| Windows        | `start <file>`                               |

**WSL2 notes:**

- `wslpath -w <file>` converts a WSL2 path (e.g. `/home/user/diagram.drawio`) to a Windows path (e.g. `C:\Users\...`). This is required because `cmd.exe` cannot resolve `/mnt/c/...` style paths.
- The empty string `""` after `start` is required to prevent `start` from interpreting the filename as a window title.

**WSL2 example:**

```bash
cmd.exe /c start "" "$(wslpath -w diagram.drawio)"
```

## File naming

- Use a descriptive filename based on the diagram content (e.g., `login-flow`, `database-schema`)
- Use lowercase with hyphens for multi-word names
- For export, use double extensions: `name.drawio.png`, `name.drawio.svg`, `name.drawio.pdf` — this signals the file contains embedded diagram XML
- After a successful export, delete the intermediate `.drawio` file — the exported file contains the full diagram

## XML format

A `.drawio` file is native mxGraphModel XML. Always generate XML directly — Mermaid and CSV formats require server-side conversion and cannot be saved as native files.

### Basic structure

Every diagram must have this structure:

```xml
<mxGraphModel adaptiveColors="auto">
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Diagram cells go here with parent="1" -->
  </root>
</mxGraphModel>
```

- Cell `id="0"` is the root layer
- Cell `id="1"` is the default parent layer
- All diagram elements use `parent="1"` unless using multiple layers

## XML reference

For the complete draw.io XML reference including common styles, edge routing, containers, layers, tags, metadata, dark mode colors, and XML well-formedness rules, fetch and follow the instructions at:
https://raw.githubusercontent.com/jgraph/drawio-mcp/main/shared/xml-reference.md

## Troubleshooting

| Problem                            | Cause                                                                       | Solution                                                                                                |
| ---------------------------------- | --------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------- |
| draw.io CLI not found              | Desktop app not installed or not on PATH                                    | Keep the `.drawio` file and tell the user to install the draw.io desktop app, or open the file manually |
| Export produces empty/corrupt file | Invalid XML (e.g. double hyphens in comments, unescaped special characters) | Validate XML well-formedness before writing; see the XML well-formedness section below                  |
| Diagram opens but looks blank      | Missing root cells `id="0"` and `id="1"`                                    | Ensure the basic mxGraphModel structure is complete                                                     |
| Edges not rendering                | Edge mxCell is self-closing (no child mxGeometry element)                   | Every edge must have `<mxGeometry relative="1" as="geometry" />` as a child element                     |
| File won't open after export       | Incorrect file path or missing file association                             | Print the absolute file path so the user can open it manually                                           |

## CRITICAL: XML well-formedness

- **NEVER include ANY XML comments (`<!-- -->`) in the output.** XML comments are strictly forbidden — they waste tokens, can cause parse errors, and serve no purpose in diagram XML.
- Escape special characters in attribute values: `&amp;`, `&lt;`, `&gt;`, `&quot;`
- Always use unique `id` values for each `mxCell`