* refactor: simplify LLM XML format to output bare mxCells only - Update wrapWithMxFile() to always add root cells (id=0, id=1) automatically - LLM now generates only mxCell elements starting from id=2 (no wrapper tags) - Update system prompts and tool descriptions with new format instructions - Update cached responses to remove root cells and wrapper tags - Update truncation detection to check for complete mxCell endings - Update documentation in xml_guide.md * fix: address PR review issues for XML format refactor - Fix critical bug: inconsistent truncation check using old </root> pattern - Fix stale error message referencing </root> tag - Add isMxCellXmlComplete() helper for consistent truncation detection - Improve regex patterns to handle any attribute order in root cells - Update wrapWithMxFile JSDoc to document root cell removal behavior * fix: handle non-self-closing root cells in wrapWithMxFile regex
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Draw.io XML Schema Guide
This guide explains the structure of draw.io (diagrams.net) XML files to help you understand and create diagrams programmatically.
Basic Structure
A draw.io XML file has the following hierarchy:
<mxfile>
<diagram>
<mxGraphModel>
<root>
<mxCell /> <!-- Cells that make up the diagram -->
</root>
</mxGraphModel>
</diagram>
</mxfile>
Root Element: <mxfile>
The root element of a draw.io file.
Attributes:
host: The application that created the file (e.g., "app.diagrams.net")modified: Last modification timestampagent: Browser / user agent informationversion: Version of the applicationtype: File type (usually "device" or "google")
Example:
<mxfile host="app.diagrams.net" modified="2023-07-14T10:20:30.123Z" agent="Mozilla/5.0" version="21.5.2" type="device">
Diagram Element: <diagram>
Each page in your draw.io document is represented by a <diagram> element.
Attributes:
id: Unique identifier for the diagramname: The name of the diagram / page
Example:
<diagram id="pWHN0msd4Ud1ZK5cD-Hr" name="Page-1">
Graph Model: <mxGraphModel>
Contains the actual diagram data.
Attributes:
dx: Grid size in x-direction (usually 1)dy: Grid size in y-direction (usually 1)grid: Whether grid is enabled (0 or 1)gridSize: Grid cell size (usually 10)guides: Whether guides are enabled (0 or 1)tooltips: Whether tooltips are enabled (0 or 1)connect: Whether connections are enabled (0 or 1)arrows: Whether arrows are enabled (0 or 1)fold: Whether folding is enabled (0 or 1)page: Whether page view is enabled (0 or 1)pageScale: Scale of the page (usually 1)pageWidth: Width of the page (e.g., 850)pageHeight: Height of the page (e.g., 1100)math: Whether math typesetting is enabled (0 or 1)shadow: Whether shadows are enabled (0 or 1)
Example:
<mxGraphModel dx="1" dy="1" grid="1" gridSize="10" guides="1" tooltips="1" connect="1" arrows="1" fold="1" page="1" pageScale="1" pageWidth="850" pageHeight="1100" math="0" shadow="0">
Root Cell Container: <root>
Contains all the cells in the diagram. Note: When generating diagrams, you only need to provide the mxCell elements - the root container and root cells (id="0", id="1") are added automatically.
Internal structure (auto-generated):
<root>
<mxCell id="0"/> <!-- Auto-added -->
<mxCell id="1" parent="0"/> <!-- Auto-added -->
<!-- Your mxCell elements go here (start from id="2") -->
</root>
Cell Elements: <mxCell>
The basic building block of diagrams. Cells represent shapes, connectors, text, etc.
Attributes for all cells:
id: Unique identifier for the cellparent: ID of the parent cell (typically "1" for most cells)value: Text content of the cellstyle: Styling information (see Style section below)
Attributes for shapes (vertices):
vertex: Set to "1" for shapesconnectable: Whether the shape can be connected (0 or 1)
Attributes for connectors (edges):
edge: Set to "1" for connectorssource: ID of the source celltarget: ID of the target cell
Example (Rectangle shape):
<mxCell id="2" value="Hello World" style="rounded=0;whiteSpace=wrap;html=1;" vertex="1" parent="1">
<mxGeometry x="350" y="190" width="120" height="60" as="geometry"/>
</mxCell>
Example (Connector):
<mxCell id="3" value="" style="endArrow=classic;html=1;rounded=0;" edge="1" parent="1" source="2" target="4">
<mxGeometry width="50" height="50" relative="1" as="geometry">
<mxPoint x="400" y="430" as="sourcePoint"/>
<mxPoint x="450" y="380" as="targetPoint"/>
</mxGeometry>
</mxCell>
Geometry: <mxGeometry>
Defines the position and dimensions of cells.
Attributes for shapes:
x: The x-coordinate of the top-left point of the shape.y: The y-coordinate of the top-left point of the shape.width: The width of the shape.height: The height of the shape.as: Specifies the role of this geometry within its parent cell. Typically set to"geometry"for the main shape definition.
Attributes for connectors:
relative: Set to "1" for relative geometryas: Set to "geometry"
Example for shapes:
<mxGeometry x="350" y="190" width="120" height="60" as="geometry"/>
Example for connectors:
<mxGeometry width="50" height="50" relative="1" as="geometry">
<mxPoint x="400" y="430" as="sourcePoint"/>
<mxPoint x="450" y="380" as="targetPoint"/>
</mxGeometry>
Cell Style Reference
Styles are specified as semicolon-separated key=value pairs in the style attribute of <mxCell> elements.
Shape-specific Styles
- Rectangle:
shape=rectangle - Ellipse:
shape=ellipse - Triangle:
shape=triangle - Rhombus:
shape=rhombus - Hexagon:
shape=hexagon - Cloud:
shape=cloud - Actor:
shape=actor - Cylinder:
shape=cylinder - Document:
shape=document - Note:
shape=note - Card:
shape=card - Parallelogram:
shape=parallelogram
Connector Styles
endArrow=classic: Arrow type at the end (classic, open, oval, diamond, block)startArrow=none: Arrow type at the start (none, classic, open, oval, diamond)curved=1: Curved connector (0 or 1)edgeStyle=orthogonalEdgeStyle: Connector routing styleelbow=vertical: Elbow direction (vertical, horizontal)jumpStyle=arc: Jump style for line crossing (arc, gap)jumpSize=10: Size of the jump
Special Cells
Draw.io files contain two special cells that are always present:
- Root Cell (id = "0"): The parent of all cells
- Default Parent Cell (id = "1", parent = "0"): The default layer and parent for most cells
Tips for Creating Draw.io XML
- Generate ONLY mxCell elements - wrapper tags and root cells (id="0", id="1") are added automatically
- Start IDs from "2" (id="0" and id="1" are reserved for root cells)
- Assign unique and sequential IDs to all cells
- Define parent relationships correctly (use parent="1" for top-level shapes)
- Use
mxGeometryelements to position shapes - For connectors, specify
sourceandtargetattributes - CRITICAL: All mxCell elements must be siblings. NEVER nest mxCell inside another mxCell.
Common Patterns
Grouping Elements
To group elements, create a parent cell and set other cells' parent attribute to its ID:
<!-- Group container -->
<mxCell id="10" value="Group" style="group" vertex="1" connectable="0" parent="1">
<mxGeometry x="200" y="200" width="200" height="100" as="geometry" />
</mxCell>
<!-- Elements inside the group -->
<mxCell id="11" value="Element 1" style="rounded=0;whiteSpace=wrap;html=1;" vertex="1" parent="10">
<mxGeometry width="90" height="40" as="geometry" />
</mxCell>
<mxCell id="12" value="Element 2" style="rounded=0;whiteSpace=wrap;html=1;" vertex="1" parent="10">
<mxGeometry x="110" width="90" height="40" as="geometry" />
</mxCell>
Swimlanes
Swimlanes use the swimlane shape style. IMPORTANT: All mxCell elements (swimlanes, steps, and edges) must be siblings under <root>. Edges are NOT nested inside swimlanes or steps.
<root>
<mxCell id="0"/>
<mxCell id="1" parent="0"/>
<!-- Swimlane 1 -->
<mxCell id="lane1" value="Frontend" style="swimlane;startSize=30;" vertex="1" parent="1">
<mxGeometry x="40" y="40" width="200" height="300" as="geometry"/>
</mxCell>
<!-- Swimlane 2 -->
<mxCell id="lane2" value="Backend" style="swimlane;startSize=30;" vertex="1" parent="1">
<mxGeometry x="280" y="40" width="200" height="300" as="geometry"/>
</mxCell>
<!-- Step inside lane1 (parent="lane1") -->
<mxCell id="step1" value="Send Request" style="rounded=1;" vertex="1" parent="lane1">
<mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
</mxCell>
<!-- Step inside lane2 (parent="lane2") -->
<mxCell id="step2" value="Process" style="rounded=1;" vertex="1" parent="lane2">
<mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
</mxCell>
<!-- Edge connecting step1 to step2 (sibling element, NOT nested inside steps) -->
<mxCell id="edge1" style="edgeStyle=orthogonalEdgeStyle;endArrow=classic;" edge="1" parent="1" source="step1" target="step2">
<mxGeometry relative="1" as="geometry"/>
</mxCell>
</root>
Tables
Tables use multiple cells with parent-child relationships:
<mxCell id="30" value="Table" style="shape=table;startSize=30;container=1;collapsible=1;childLayout=tableLayout;fixedRows=1;rowLines=0;fontStyle=1;align=center;resizeLast=1;html=1;" vertex="1" parent="1">
<mxGeometry x="200" y="200" width="180" height="120" as="geometry" />
</mxCell>
<mxCell id="31" value="" style="shape=tableRow;horizontal=0;startSize=0;swimlaneHead=0;swimlaneBody=0;fillColor=none;collapsible=0;dropTarget=0;points=[0,0.5,1,0.5];portConstraint=eastwest;top=0;left=0;right=0;bottom=1;" vertex="1" parent="30">
<mxGeometry y="30" width="180" height="30" as="geometry" />
</mxCell>
Advanced Features
Custom Attributes
Draw.io allows adding custom attributes to cells:
<mxCell id="40" value="Custom Element" style="rounded=0;whiteSpace=wrap;html=1;" vertex="1" parent="1">
<mxGeometry x="200" y="200" width="120" height="60" as="geometry"/>
<Object label="Custom Label" customAttr="value" />
</mxCell>
These custom attributes can store additional metadata or be used by plugins and custom behaviors.
User-defined Styles
You can define custom styles for cells by combining various style attributes:
<mxCell id="50" value="Custom Styled Cell"
style="shape=hexagon;perimeter=hexagonPerimeter2;whiteSpace=wrap;html=1;fixedSize=1;fillColor=#f8cecc;strokeColor=#b85450;strokeWidth=2;fontSize=14;fontStyle=1"
vertex="1" parent="1">
<mxGeometry x="300" y="200" width="120" height="80" as="geometry"/>
</mxCell>
Layers
You can create multiple layers in a diagram to organize complex diagrams:
<!-- Default layer (always present) -->
<mxCell id="1" parent="0"/>
<!-- Additional custom layer -->
<mxCell id="60" value="Layer 2" style="locked=0;group=" parent="0"/>
<!-- Elements in Layer 2 -->
<mxCell id="61" value="Element in Layer 2" style="rounded=0;whiteSpace=wrap;html=1;" vertex="1" parent="60">
<mxGeometry x="200" y="300" width="120" height="60" as="geometry"/>
</mxCell>