Drawio Skill

Draw.io Diagrams

Overview

Generate .drawio XML files and export to PNG/SVG/PDF/JPG locally using the native draw.io desktop app CLI.

Supported formats: PNG, SVG, PDF, JPG — no browser automation needed.

PNG, SVG, and PDF exports support --embed-diagram (-e) — the exported file contains the full diagram XML, so opening it in draw.io recovers the editable diagram. Use double extensions (name.drawio.png) to signal embedded XML.

When to Use

Explicit triggers: user says "diagram", "visualize", "flowchart", "draw", "architecture diagram", "process flow", "ER diagram", "UML", "sequence diagram", "class diagram", "neural network", "model architecture"

Proactive triggers:

• Explaining a system with 3+ interacting components
• Describing a multi-step process or decision tree
• Comparing architectures or approaches side by side

Skip when: a simple list or table suffices, or user is in a quick Q&A flow

Prerequisites

The draw.io desktop app must be installed and the CLI accessible:

# macOS (Homebrew — recommended)
brew install --cask drawio
draw.io --version

# macOS (full path if not in PATH)
/Applications/draw.io.app/Contents/MacOS/draw.io --version

# Windows
"C:\Program Files\draw.io\draw.io.exe" --version

# Linux
draw.io --version

Install draw.io desktop if missing:

• macOS: brew install --cask drawio or download from https://github.com/jgraph/drawio-desktop/releases
• Windows: download installer from https://github.com/jgraph/drawio-desktop/releases
• Linux: download .deb/.rpm from https://github.com/jgraph/drawio-desktop/releases

Workflow

Before starting the workflow, assess whether the user's request is specific enough. If key details are missing, ask 1-3 focused questions:

• Diagram type — which preset? (ERD, UML, Sequence, Architecture, ML/DL, Flowchart, or general)
• Output format — PNG (default), SVG, PDF, or JPG?
• Scope/fidelity — how many components? Any specific technologies or labels?

Skip clarification if the request already specifies these details or is clearly simple (e.g., "draw a flowchart of X").

1. Check deps — verify draw.io --version succeeds; note platform for correct CLI path
2. Plan — identify shapes, relationships, layout (LR or TB), group by tier/layer
3. Generate — write .drawio XML file to disk (output dir same as user's working dir)
4. Export draft — run CLI to produce PNG for preview
5. Self-check — use the agent's built-in vision capability to read the exported PNG, catch obvious issues, auto-fix before showing user (requires a vision-enabled model such as Claude Sonnet/Opus)
6. Review loop — show image to user, collect feedback, apply targeted XML edits, re-export, repeat until approved
7. Final export — export approved version to all requested formats, report file paths

Step 5: Self-Check

After exporting the draft PNG, use the agent's vision capability (e.g., Claude's image input) to read the image and check for these issues before showing the user. If the agent does not support vision, skip self-check and show the PNG directly:

| Check | What to look for | Auto-fix action | |-------|-----------------|-----------------| | Overlapping shapes | Two or more shapes stacked on top of each other | Shift shapes apart by ≥200px | | Clipped labels | Text cut off at shape boundaries | Increase shape width/height to fit label | | Missing connections | Arrows that don't visually connect to shapes | Verify source/target ids match existing cells | | Off-canvas shapes | Shapes at negative coordinates or far from the main group | Move to positive coordinates near the cluster | | Edge-shape overlap | An edge/arrow visually crosses through an unrelated shape | Add waypoints (``) to route around the shape, or increase spacing between shapes | | Stacked edges | Multiple edges overlap each other on the same path | Distribute entry/exit points across the shape perimeter (use different exitX/entryX values) |

• Max 2 self-check rounds — if issues remain after 2 fixes, show the user anyway
• Re-export after each fix and re-read the new PNG

Step 6: Review Loop

After self-check, show the exported image and ask the user for feedback.

Targeted edit rules — for each type of feedback, apply the minimal XML change:

| User request | XML edit action | |-------------|----------------| | Change color of X | Find mxCell by value matching X, update fillColor/strokeColor in style | | Add a new node | Append a new mxCell vertex with next available id, position near related nodes | | Remove a node | Delete the mxCell vertex and any edges with matching source/target | | Move shape X | Update x/y in the mxGeometry of the matching mxCell | | Resize shape X | Update width/height in the mxGeometry of the matching mxCell | | Add arrow from A to B | Append a new mxCell edge with source/target matching A and B ids | | Change label text | Update the value attribute of the matching mxCell | | Change layout direction | Full regeneration — rebuild XML with new orientation |

Rules:

• For single-element changes: edit existing XML in place — preserves layout tuning from prior iterations
• For layout-wide changes (e.g., swap LR↔TB, "start over"): regenerate full XML
• Overwrite the same {name}.png each iteration — do not create v1, v2, v3 files
• After applying edits, re-export and show the updated image
• Loop continues until user says approved / done / LGTM
• Safety valve: after 5 iteration rounds, suggest the user open the .drawio file in draw.io desktop for fine-grained adjustments

Step 7: Final Export

Once the user approves:

• Export to all requested formats (PNG, SVG, PDF, JPG) — default to PNG if not specified
• Report file paths for both the .drawio source file and exported image(s)
• Auto-launch: offer to open the .drawio file in draw.io desktop for fine-tuning — open diagram.drawio (macOS), xdg-open (Linux), start (Windows)
• Confirm files are saved and ready to use

Draw.io XML Structure

File skeleton

Rules:

• id="0" and id="1" are required root cells — never omit them
• User shapes start at id="2" and increment sequentially
• All shapes have parent="1" (unless inside a container — then use container's id)
• All text uses html=1 in style for proper rendering
• Never use -- inside XML comments — it's illegal per XML spec and causes parse errors
• Escape special characters in attribute values: &, <, >, "
• Multi-line text in labels: use 
 for line breaks inside value attributes (not literal \n). Example: value="Line 1
Line 2"

Shape types (vertex)

| Style keyword | Use for | |--------------|---------| | rounded=0 | plain rectangle (default) | | rounded=1 | rounded rectangle — services, modules | | ellipse; | circles/ovals — start/end, databases | | rhombus; | diamond — decision points | | shape=mxgraph.aws4.resourceIcon; | AWS icons | | shape=cylinder3; | cylinder — databases | | swimlane; | group/container with title bar |

Required properties

Containers and groups

For architecture diagrams with nested elements, use draw.io's parent-child containment — do not just place shapes on top of larger shapes.

| Type | Style | When to use | |------|-------|-------------| | Group (invisible) | group;pointerEvents=0; | No visual border needed, container has no connections | | Swimlane (titled) | swimlane;startSize=30; | Container needs a visible title bar, or container itself has connections | | Custom container | Add container=1;pointerEvents=0; to any shape | Any shape acting as a container without its own connections |

Key rules:

• Add pointerEvents=0; to container styles that should not capture connections between children
• Children set parent="containerId" and use coordinates relative to the container

Connector (edge)

CRITICAL: Every edge mxCell must contain a ` child element. Self-closing edge cells (`) are invalid and will not render. Always use the expanded form.

Edge style rules:

• Animated connectors: add flowAnimation=1; to any edge style to show a moving dot animation along the arrow. Works in SVG export and draw.io desktop — ideal for data-flow and pipeline diagrams. Example: style="edgeStyle=orthogonalEdgeStyle;flowAnimation=1;rounded=1;..."
• Always include rounded=1;orthogonalLoop=1;jettySize=auto — these enable smart routing that avoids overlaps
• Pin exitX/exitY/entryX/entryY on every edge when a node has 2+ connections — distributes lines across the shape perimeter
• Add `` waypoints when an edge must detour around an intermediate shape
• Leave room for arrowheads: the final straight segment between the last bend and the target shape must be ≥20px long. If too short, the arrowhead overlaps the bend and looks broken. Fix by increasing node spacing or adding explicit waypoints

Distributing connections on a shape

When multiple edges connect to the same shape, assign different entry/exit points to prevent stacking:

| Position | exitX/entryX | exitY/entryY | Use when | |----------|-------------|-------------|----------| | Top center | 0.5 | 0 | connecting to node above | | Top-left | 0.25 | 0 | 2nd connection from top | | Top-right | 0.75 | 0 | 3rd connection from top | | Right center | 1 | 0.5 | connecting to node on right | | Bottom center | 0.5 | 1 | connecting to node below | | Left center | 0 | 0.5 | connecting to node on left |

Rule: if a shape has N connections on one side, space them evenly (e.g., 3 connections on bottom → exitX = 0.25, 0.5, 0.75)

Color palette (fillColor / strokeColor)

| Color name | fillColor | strokeColor | Use for | |-----------|-----------|-------------|---------| | Blue | #dae8fc | #6c8ebf | services, clients | | Green | #d5e8d4 | #82b366 | success, databases | | Yellow | #fff2cc | #d6b656 | queues, decisions | | Orange | #ffe6cc | #d79b00 | gateways, APIs | | Red/Pink | #f8cecc | #b85450 | errors, alerts | | Grey | #f5f5f5 | #666666 | external/neutral | | Purple | #e1d5e7 | #9673a6 | security, auth |

Layout tips

Spacing — scale with complexity:

| Diagram complexity | Nodes | Horizontal gap | Vertical gap | |-------------------|-------|----------------|--------------| | Simple | ≤5 | 200px | 150px | | Medium | 6–10 | 280px | 200px | | Complex | >10 | 350px | 250px |

Routing corridors: between shape rows/columns, leave an extra ~80px empty corridor where edges can route without crossing shapes. Never place a shape in a gap that edges need to traverse.

Grid alignment: snap all x, y, width, height values to multiples of 10 — this ensures shapes align cleanly on draw.io's default grid and makes manual editing easier.

General rules:

• Plan a grid before assigning x/y coordinates — sketch node positions on paper/mentally first
• Group related nodes in the same horizontal or vertical band
• Use swimlane cells for logical grouping with visible borders
• Place heavily-connected "hub" nodes centrally so edges radiate outward instead of crossing
• To force straight vertical connections, pin entry/exit points explicitly on edges:

exitX=0.5;exitY=1;exitDx=0;exitDy=0;entryX=0.5;entryY=0;entryDx=0;entryDy=0

• Always center-align a child node under its parent (same center x) to avoid diagonal routing
• Event bus pattern: place Kafka/bus nodes in the center of the service row, not below — services on either side can reach it with short horizontal arrows (exitX=1 left side, exitX=0 right side), eliminating all line crossings
• Horizontal connections (exitX=1 or exitX=0) never cross vertical nodes in the same row; use them for peer-to-peer and publish connections

Avoiding edge-shape overlap:

• Before finalizing coordinates, trace each edge path mentally — if it must cross an unrelated shape, either move the shape or add waypoints
• For tree/hierarchical layouts: assign nodes to layers (rows), connect only between adjacent layers to minimize crossings
• For star/hub layouts: place the hub center, satellites around it — edges stay short and radial
• When an edge must span multiple rows/columns, route it along the outer corridor, not through the middle of the diagram

Export

Commands

# macOS — Homebrew (draw.io in PATH)
draw.io -x -f png -e -s 2 -o diagram.drawio.png input.drawio

# macOS — full path (if not in PATH)
/Applications/draw.io.app/Contents/MacOS/draw.io -x -f png -e -s 2 -o diagram.drawio.png input.drawio

# Windows
"C:\Program Files\draw.io\draw.io.exe" -x -f png -e -s 2 -o diagram.drawio.png input.drawio

# Linux (headless — requires xvfb-run)
xvfb-run -a draw.io -x -f png -e -s 2 -o diagram.drawio.png input.drawio

# SVG export
draw.io -x -f svg -o diagram.svg input.drawio

# PDF export
draw.io -x -f pdf -o diagram.pdf input.drawio

Key flags:

• -x — export mode (required)
• -f — format: png, svg, pdf, jpg
• -e — embed diagram XML in output (PNG, SVG, PDF only) — exported file remains editable in draw.io
• -s — scale: 1, 2, 3 (2 recommended for PNG)
• -o — output file path (use .drawio.png double extension when embedding)
• -b — border width around diagram (default: 0, recommend 10)
• -t — transparent background (PNG only)
• --page-index 0 — export specific page (default: all)

Browser fallback (no CLI needed)

When the draw.io desktop CLI is unavailable, generate a browser-editable URL by deflate-compressing and base64-encoding the XML:

# Encode .drawio XML into a diagrams.net URL
python3 -c "
import zlib, base64, urllib.parse, sys
xml = open(sys.argv[1]).read()
compressed = zlib.compress(xml.encode('utf-8'), 9)
encoded = base64.urlsafe_b64encode(compressed).decode('utf-8')
print('https://viewer.diagrams.net/?tags=%7B%7D&lightbox=1&edit=_blank#R' + urllib.parse.quote(encoded, safe=''))
" input.drawio

This produces a client-side URL that opens the diagram in the browser for viewing and editing. No data is uploaded to any server — the entire diagram XML is encoded in the URL fragment (after #), which is never sent to the server. Useful when the user cannot install the desktop app.

Fallback chain

When tools are unavailable, degrade gracefully:

| Scenario | Behavior | |----------|----------| | draw.io CLI missing, Python available | Use browser fallback (diagrams.net URL) | | draw.io CLI missing, Python missing | Generate .drawio XML only; instruct user to open in draw.io desktop or diagrams.net manually | | Vision unavailable for self-check | Skip self-check (step 5); proceed directly to showing user the exported PNG | | Export fails (Chromium/display issues) | On Linux, retry with xvfb-run -a; if still failing, deliver .drawio XML and suggest manual export |

Checking if draw.io is in PATH

# Try short command first
if command -v draw.io &>/dev/null; then
  DRAWIO="draw.io"
elif [ -f "/Applications/draw.io.app/Contents/MacOS/draw.io" ]; then
  DRAWIO="/Applications/draw.io.app/Contents/MacOS/draw.io"
else
  echo "draw.io not found — install from https://github.com/jgraph/drawio-desktop/releases"
fi

Common Mistakes

| Mistake | Fix | |---------|-----| | Missing id="0" and id="1" root cells | Always include both at the top of ` | | Shapes not connected | source and target on edge must match existing shape id values | | Export command not found on macOS | Try full path /Applications/draw.io.app/Contents/MacOS/draw.io | | Linux: blank/error output headlessly | Prefix command with xvfb-run -a` | | PDF export fails | Ensure Chromium is available (draw.io bundles it on desktop) | | Background c

…

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: bushuhui
• Source: bushuhui/skills
• License: MIT

Install and usage instructions live in the source repository linked above.