Awesome-copilot draw-io-diagram-generator

Use when creating, editing, or generating draw.io diagram files (.drawio, .drawio.svg, .drawio.png). Covers mxGraph XML authoring, shape libraries, style strings, flowcharts, system architecture, sequence diagrams, ER diagrams, UML class diagrams, network topology, layout strategy, the hediet.vscode-drawio VS Code extension, and the full agent workflow from request to a ready-to-open file.

install

source · Clone the upstream repo

git clone https://github.com/github/awesome-copilot

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/github/awesome-copilot "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/draw-io-diagram-generator" ~/.claude/skills/github-awesome-copilot-draw-io-diagram-generator && rm -rf "$T"

manifest: skills/draw-io-diagram-generator/SKILL.md

Draw.io Diagram Generator

This skill enables you to generate, edit, and validate draw.io (

.drawio

) diagram files with correct mxGraph XML structure. All generated files open immediately in the Draw.io VS Code extension (

hediet.vscode-drawio

) without any manual fixes required. You can also open the files in the draw.io web app or desktop app if you prefer.

1. When to Use This Skill

Trigger phrases (load this skill when you see these)

"create a diagram", "draw a flowchart", "generate an architecture diagram"
"design a sequence diagram", "make a UML class diagram", "build an ER diagram"
"add a .drawio file", "update the diagram", "visualise the flow"
"document the architecture", "show the data model", "diagram the service interactions"
Any request to produce or modify a
```
.drawio
```
,
```
.drawio.svg
```
, or
```
.drawio.png
```
file

Supported diagram types

Diagram Type	Template Available	Description
Flowchart	`assets/templates/flowchart.drawio`	Process flows with decisions and branches
System Architecture	`assets/templates/architecture.drawio`	Multi-tier / layered service architecture
Sequence Diagram	`assets/templates/sequence.drawio`	Actor lifelines and timed message flows
ER Diagram	`assets/templates/er-diagram.drawio`	Database tables with relationships
UML Class Diagram	`assets/templates/uml-class.drawio`	Classes, interfaces, enums, relationships
Network Topology	(use shape library)	Routers, servers, firewalls, subnets
BPMN Workflow	(use shape library)	Business process events, tasks, gateways
Mind Map	(manual)	Central topic with radiating branches

2. Prerequisites

If running with VS Code integration enabled, Install the drawio extension: draw.io VS Code extension —
```
hediet.vscode-drawio
```
(extension id). Install with:
```
ext install hediet.vscode-drawio
```
Supported file extensions:
```
.drawio
```
,
```
.drawio.svg
```
,
```
.drawio.png
```
Python 3.8+ (optional) — for the validation and shape-insertion scripts in
```
scripts/
```

3. Step-by-Step Agent Workflow

Follow these steps in order for every diagram generation task.

Step 1 — Understand the Request

Ask or infer:

Diagram type — What kind of diagram? (flowchart, architecture, UML, ER, sequence, network...)
Entities / actors — What are the main components, actors, classes, or tables?
Relationships — How are they connected? What direction? What cardinality?
Output path — Where should the
```
.drawio
```
file be saved?
Existing file — Are we creating new or editing an existing file?

If the request is ambiguous, infer the most sensible diagram type from context (e.g. "show the tables" → ER diagram, "show how the API call flows" → sequence diagram).

Step 2 — Select a Template or Start Fresh

Use a template when the diagram type matches one in
```
assets/templates/
```
. Copy the template structure and replace placeholder values.
Start fresh for novel layouts. Begin with the minimal valid skeleton:

<!-- Set modified="" to the current ISO 8601 timestamp when generating a new file -->
<mxfile host="Electron" modified="" version="26.0.0">
  <diagram id="page-1" name="Page-1">
    <mxGraphModel dx="1422" dy="762" grid="1" gridSize="10" guides="1"
                  tooltips="1" connect="1" arrows="1" fold="1"
                  page="1" pageScale="1" pageWidth="1169" pageHeight="827"
                  math="0" shadow="0">
      <root>
        <mxCell id="0" />
        <mxCell id="1" parent="0" />
        <!-- Your cells go here -->
      </root>
    </mxGraphModel>
  </diagram>
</mxfile>

Rule: ids
0
and
1
are ALWAYS required and must be the first two cells. Never reuse them.

Step 3 — Plan the Layout

Before generating XML, sketch the logical placement:

Organise into rows or tiers (use swimlanes for layers)
Horizontal spacing: 40–60px between same-row shapes
Vertical spacing: 80–120px between tier rows
Standard shape size:
```
120x60
```
px for process boxes,
```
160x80
```
px for swimlanes
Default canvas: A4 landscape =
```
1169 x 827
```
px

Step 4 — Generate the mxGraph XML

Vertex cell (every shape):

<mxCell id="unique-id" value="Label"
        style="rounded=1;whiteSpace=wrap;html=1;fillColor=#dae8fc;strokeColor=#6c8ebf;"
        vertex="1" parent="1">
  <mxGeometry x="100" y="100" width="120" height="60" as="geometry" />
</mxCell>

Edge cell (every connector):

<mxCell id="edge-id" value="Label (optional)"
        style="edgeStyle=orthogonalEdgeStyle;html=1;"
        edge="1" source="source-id" target="target-id" parent="1">
  <mxGeometry relative="1" as="geometry" />
</mxCell>

Critical rules:

Every cell id must be globally unique within the file
Every vertex must have an
```
mxGeometry
```
child with
```
x
```
,
```
y
```
,
```
width
```
,
```
height
```
,
```
as="geometry"
```
Every edge must have
```
source
```
and
```
target
```
matching existing vertex ids — exception: floating edges (e.g. sequence diagram lifelines) use
```
sourcePoint
```
/
```
targetPoint
```
inside
```
<mxGeometry>
```
instead; see §4 Sequence Diagram
Every cell's
```
parent
```
must reference an existing cell id
Use
```
html=1
```
in style when the label contains HTML (
```
<b>
```
,
```
<i>
```
,
```
<br>
```
)
Escape XML special characters in labels:
```
&
```
=>
```
&amp;
```
,
```
<
```
=>
```
&lt;
```
,
```
>
```
=>
```
&gt;
```

Step 5 — Apply Correct Styles

Use the standard semantic color palette for consistency:

Purpose	fillColor	strokeColor
Primary / Info	`#dae8fc`	`#6c8ebf`
Success / Start	`#d5e8d4`	`#82b366`
Warning / Decision	`#fff2cc`	`#d6b656`
Error / End	`#f8cecc`	`#b85450`
Neutral	`#f5f5f5`	`#666666`
External / Partner	`#e1d5e7`	`#9673a6`

Common style strings by diagram type:

# Rounded process box (flowchart)
rounded=1;whiteSpace=wrap;html=1;fillColor=#dae8fc;strokeColor=#6c8ebf;

# Decision diamond
rhombus;whiteSpace=wrap;html=1;fillColor=#fff2cc;strokeColor=#d6b656;

# Start/End terminal
ellipse;whiteSpace=wrap;html=1;fillColor=#d5e8d4;strokeColor=#82b366;

# Database cylinder
shape=mxgraph.flowchart.database;whiteSpace=wrap;html=1;fillColor=#f8cecc;strokeColor=#b85450;

# Swimlane container (tier)
swimlane;startSize=30;fillColor=#dae8fc;strokeColor=#6c8ebf;fontStyle=1;

# UML class box
swimlane;fontStyle=1;align=center;startSize=40;fillColor=#dae8fc;strokeColor=#6c8ebf;

# Interface / stereotype box
swimlane;fontStyle=3;align=center;startSize=40;fillColor=#f5f5f5;strokeColor=#666666;

# ER table container
shape=table;startSize=30;container=1;collapsible=1;childLayout=tableLayout;

# Orthogonal connector
edgeStyle=orthogonalEdgeStyle;html=1;

# ER relationship (crow's foot)
edgeStyle=entityRelationEdgeStyle;html=1;endArrow=ERmany;startArrow=ERone;

See
references/style-reference.md
for the complete style key catalog and
references/shape-libraries.md
for all shape library names.

Step 6 — Save and Validate

Write the file to the requested path with
```
.drawio
```
extension

Run the validator (optional but recommended):

python .github/skills/draw-io-diagram-generator/scripts/validate-drawio.py <path-to-file.drawio>

Tell the user how to open the file:
"Open
```
<filename>
```
in VS Code — it will render automatically with the draw.io extension. You can use draw.io's web app or desktop app as well if you prefer."
Provide a brief description of what is in the diagram so the user knows what to expect.

4. Diagram-Type Recipes

Flowchart

Key elements: Start (ellipse) => Process (rounded rectangle) => Decision (diamond) => End (ellipse)

<!-- Start node -->
<mxCell id="start" value="Start"
        style="ellipse;whiteSpace=wrap;html=1;fillColor=#d5e8d4;strokeColor=#82b366;"
        vertex="1" parent="1">
  <mxGeometry x="500" y="80" width="120" height="60" as="geometry" />
</mxCell>

<!-- Process -->
<mxCell id="p1" value="Process Step"
        style="rounded=1;whiteSpace=wrap;html=1;fillColor=#dae8fc;strokeColor=#6c8ebf;"
        vertex="1" parent="1">
  <mxGeometry x="500" y="200" width="120" height="60" as="geometry" />
</mxCell>

<!-- Decision -->
<mxCell id="d1" value="Condition?"
        style="rhombus;whiteSpace=wrap;html=1;fillColor=#fff2cc;strokeColor=#d6b656;"
        vertex="1" parent="1">
  <mxGeometry x="460" y="320" width="200" height="100" as="geometry" />
</mxCell>

<!-- Arrow: start to p1 -->
<mxCell id="e1" value=""
        style="edgeStyle=orthogonalEdgeStyle;html=1;"
        edge="1" source="start" target="p1" parent="1">
  <mxGeometry relative="1" as="geometry" />
</mxCell>

Architecture Diagram (3-tier)

Use swimlane containers for each tier. All service boxes are children of their swimlane.

<!-- Tier swimlane -->
<mxCell id="tier1" value="Client Layer"
        style="swimlane;startSize=30;fillColor=#dae8fc;strokeColor=#6c8ebf;fontStyle=1;"
        vertex="1" parent="1">
  <mxGeometry x="60" y="100" width="1050" height="130" as="geometry" />
</mxCell>

<!-- Service inside tier (parent="tier1", coords are relative to tier) -->
<mxCell id="webapp" value="Web App"
        style="rounded=1;whiteSpace=wrap;html=1;fillColor=#dae8fc;strokeColor=#6c8ebf;"
        vertex="1" parent="tier1">
  <mxGeometry x="80" y="40" width="120" height="60" as="geometry" />
</mxCell>

Connectors between tiers use absolute coordinates with
parent="1"
.

Sequence Diagram

Key elements: Actors (top), Lifelines (dashed vertical lines), Activation boxes, Message arrows.

Lifelines:
```
edge="1"
```
with
```
endArrow=none
```
and
```
dashed=1
```
, no source/target — use
```
sourcePoint
```
/
```
targetPoint
```
in geometry
Synchronous message:
```
endArrow=block;endFill=1
```
Return message:
```
endArrow=open;endFill=0;dashed=1
```
Self-call: loop the edge via two Array points to the right and back

Minimal XML snippet:

<!-- Actor (stick figure) -->
<mxCell id="actorA" value="Client"
        style="shape=mxgraph.uml.actor;pointerEvents=1;dashed=0;whiteSpace=wrap;html=1;aspect=fixed;"
        vertex="1" parent="1">
  <mxGeometry x="110" y="80" width="60" height="80" as="geometry" />
</mxCell>

<!-- Service box -->
<mxCell id="actorB" value="API Server"
        style="rounded=1;whiteSpace=wrap;html=1;fillColor=#fff2cc;strokeColor=#d6b656;"
        vertex="1" parent="1">
  <mxGeometry x="480" y="100" width="160" height="60" as="geometry" />
</mxCell>

<!-- Lifeline — floating edge: uses sourcePoint/targetPoint, NOT source/target attributes -->
<mxCell id="lifA" value=""
        style="edgeStyle=none;dashed=1;endArrow=none;"
        edge="1" parent="1">
  <mxGeometry relative="1" as="geometry">
    <mxPoint x="140" y="160" as="sourcePoint" />
    <mxPoint x="140" y="700" as="targetPoint" />
  </mxGeometry>
</mxCell>

<!-- Activation box (thin rectangle on lifeline) -->
<mxCell id="actA1" value=""
        style="fillColor=#dae8fc;strokeColor=#6c8ebf;"
        vertex="1" parent="1">
  <mxGeometry x="130" y="220" width="20" height="180" as="geometry" />
</mxCell>

<!-- Synchronous message -->
<mxCell id="msg1" value="POST /orders"
        style="edgeStyle=elbowEdgeStyle;elbow=vertical;html=1;endArrow=block;endFill=1;"
        edge="1" source="actA1" target="actorB" parent="1">
  <mxGeometry relative="1" as="geometry" />
</mxCell>

<!-- Return message (dashed) -->
<mxCell id="msg2" value="201 Created"
        style="edgeStyle=elbowEdgeStyle;elbow=vertical;dashed=1;html=1;endArrow=open;endFill=0;"
        edge="1" source="actorB" target="actA1" parent="1">
  <mxGeometry relative="1" as="geometry" />
</mxCell>

Note: Lifelines are floating edges that use
sourcePoint
/
targetPoint
in
<mxGeometry>
instead of
source
/
target
attributes. This is the standard draw.io pattern for sequence diagrams.

ER Diagram

Use

shape=table

containers with

childLayout=tableLayout

. Rows are

shape=tableRow

cells with

portConstraint=eastwest

. Columns inside each row are

shape=partialRectangle

Relationship arrows use

edgeStyle=entityRelationEdgeStyle

One-to-One:
```
startArrow=ERone;endArrow=ERone
```
One-to-Many:
```
startArrow=ERone;endArrow=ERmany
```
Many-to-Many:
```
startArrow=ERmany;endArrow=ERmany
```
Mandatory:
```
ERmandOne
```
, Optional:
```
ERzeroToOne
```

UML Class Diagram

Class boxes are swimlane containers. Attributes and methods are plain text cells. Dividers are zero-height swimlane children.

Arrow styles by relationship type:

Relationship	Style String
Inheritance (extends)	`edgeStyle=orthogonalEdgeStyle;html=1;endArrow=block;endFill=0;`
Realization (implements)	`edgeStyle=orthogonalEdgeStyle;dashed=1;html=1;endArrow=block;endFill=0;`
Composition	`edgeStyle=orthogonalEdgeStyle;html=1;startArrow=diamond;startFill=1;endArrow=none;`
Aggregation	`edgeStyle=orthogonalEdgeStyle;html=1;startArrow=diamond;startFill=0;endArrow=none;`
Dependency	`edgeStyle=orthogonalEdgeStyle;dashed=1;html=1;endArrow=open;endFill=0;`
Association	`edgeStyle=orthogonalEdgeStyle;html=1;endArrow=open;endFill=0;`

5. Multi-Page Diagrams

Add multiple

<diagram>

elements for complex systems:

<mxfile host="Electron" version="26.0.0">
  <diagram id="overview" name="Overview">
    <!-- overview mxGraphModel -->
  </diagram>
  <diagram id="detail" name="Detail View">
    <!-- detail mxGraphModel -->
  </diagram>
</mxfile>

Each page has its own independent cell id namespace. The same id value can appear in different pages without conflict.

6. Editing Existing Diagrams

When modifying an existing

.drawio

file:

Read the file first to understand existing cell ids, positions, and parent hierarchy
Identify the target diagram page — by index or
```
name
```
attribute
Assign new unique ids that do not collide with existing ids
Respect the container hierarchy — children of a swimlane use coordinates relative to their parent
Verify edges — after repositioning nodes, confirm edge source/target ids remain valid

Use

scripts/add-shape.py

to safely add a single shape without editing raw XML:

python .github/skills/draw-io-diagram-generator/scripts/add-shape.py docs/arch.drawio "New Service" 700 380

7. Best Practices

Layout

Align shapes to the 10px grid (all coordinates divisible by 10)
Group related shapes inside swimlane containers
One diagram topic per page; use multi-page files for complex systems
Aim for 40 or fewer cells per page for readability

Labels

Add a title text cell (

text;strokeColor=none;fillColor=none;fontSize=18;fontStyle=1

) at top of every page

Always set
```
whiteSpace=wrap;html=1
```
on vertex shapes
Keep labels concise — 3 words or fewer per shape where possible

Style consistency

Use the semantic color palette from Section 3 Step 5 consistently across a project
Prefer
```
edgeStyle=orthogonalEdgeStyle
```
for clean right-angle connectors
Do not inline arbitrary HTML in labels unless necessary

File naming

Use kebab-case:

order-service-flow.drawio

database-schema.drawio

Place diagrams alongside the code they document:
```
docs/
```
or
```
architecture/
```

8. Troubleshooting

Problem	Likely Cause	Fix
File opens blank in VS Code	Missing id=0 or id=1 cell	Add both root cells before any other cells
Shape at wrong position	Child inside container — coords are relative	Check `parent` ; adjust x/y relative to container
Edge not visible	source or target id does not match any vertex	Verify both ids exist exactly as written
Diagram shows "Compressed"	mxGraphModel is base64-encoded	Open in draw.io web, File > Export > XML (uncompressed)
Shape style not rendering	Typo in shape= name	Check `references/shape-libraries.md` for exact style string
Label shows escaped HTML	html=0 on a cell with HTML label	Add `html=1;` to the cell style
Container children overlap container edge	Container height too small	Increase container height in mxGeometry

9. Validation Checklist

Before delivering any generated

.drawio

file, verify:

File starts with
```
<mxfile>
```
root element
Every
```
<diagram>
```
has a non-empty
```
id
```
attribute
```
<mxCell id="0" />
```
is the first cell in every diagram
```
<mxCell id="1" parent="0" />
```
is the second cell in every diagram
All cell
```
id
```
values are unique within each diagram
Every vertex cell has
```
vertex="1"
```
and a child
```
<mxGeometry as="geometry">
```
Every edge cell has
```
edge="1"
```
and either: (a)
```
source
```
/
```
target
```
pointing to existing vertex ids, or (b)
```
<mxPoint as="sourcePoint">
```
and
```
<mxPoint as="targetPoint">
```
in its
```
<mxGeometry>
```
(floating edge — used for sequence diagram lifelines)
Every cell (except id=0) has a
```
parent
```
pointing to an existing id
```
html=1
```
is in the style for any label containing HTML tags
XML is well-formed (no unclosed tags, no unescaped
```
&
```
,
```
<
```
,
```
>
```
in attribute values)
A title label cell exists at the top of each page

Run the automated validator:

python .github/skills/draw-io-diagram-generator/scripts/validate-drawio.py <file.drawio>

10. Output Format

When delivering a diagram, always provide:

The
.drawio
file written to the requested path
A one-sentence summary of what the diagram shows
How to open it:
"Open
```
<filename>
```
in VS Code — the draw.io extension will render it automatically. Or you can open it in the draw.io web app or desktop app if you prefer."
How to edit it (if the user is likely to customise):

"Click any shape to select it. Double-click to edit the label. Drag to reposition."
Validation status — whether the validator script was run and passed

11. References

All companion files are in

.github/skills/draw-io-diagram-generator/

File	Contents
`references/drawio-xml-schema.md`	Complete mxfile / mxGraphModel / mxCell attribute reference, coordinate system, reserved cells, validation rules
`references/style-reference.md`	All style keys with allowed values, vertex and edge style keys, shape catalog, semantic color palette
`references/shape-libraries.md`	All shape library categories (General, Flowchart, UML, ER, Network, BPMN, Mockup, K8s) with style strings
`assets/templates/flowchart.drawio`	Ready-to-use flowchart template
`assets/templates/architecture.drawio`	4-tier system architecture template
`assets/templates/sequence.drawio`	3-actor sequence diagram template
`assets/templates/er-diagram.drawio`	3-table ER diagram with crow's foot relationships
`assets/templates/uml-class.drawio`	Interface + 2 classes + enum with relationship arrows
`scripts/validate-drawio.py`	Python script to validate XML structure of any .drawio file
`scripts/add-shape.py`	Python CLI to add a new shape to an existing diagram
`scripts/README.md`	How to use the scripts with examples