mrlyk/anthropic-diagram

Anthropic-Style Diagram Skill

Generate draw.io diagrams that match the editorial, warm, minimalist visual style of Anthropic's blog article illustrations.

Workflow

User text → DiagramSpec (written out as text) → Styled draw.io XML → .drawio file

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Step 1: Analyze the Request

Determine:

• Main claim: What is the one thing this diagram should make obvious?
• Pattern: Which visual pattern best serves that claim? (See Step 2 and references/pattern-library.md)
• Reading direction: left-to-right for workflows/comparisons; top-to-bottom for stacks/hierarchies

When uncertain about pattern, default rules:

• Sequential steps → Linear Workflow
• System components/containment → Grouped Architecture
• Before/after or two approaches → Split Comparison
• Multiple actors over time → Swimlane
• Overlap/shared ownership → Venn
• Numerical contrast → Editorial Chart

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Step 2: Build the DiagramSpec

Before writing any XML, write out the diagram plan explicitly as text — this helps catch structural mistakes before committing to XML, and lets the user see your reasoning. Output the DiagramSpec in this format:

**DiagramSpec**

main_claim: [one sentence — what is the diagram making obvious?]
pattern: [primary pattern]
secondary_pattern: [optional, or none]
reading_direction: [left-to-right / top-to-bottom]
title: "Diagram Title"

nodes:
  - id: n1
    label: "Short label"
    semantic_type: [primary | secondary | tertiary | start | end | warning | decision | ai_llm | inactive | error]
    shape: [rect | pill | diamond | cylinder]
    group: [container_id if inside a container, else none]

connections:
  - from: n1
    to: n2
    label: ""          # keep short or empty
    style: [primary | optional | feedback | human | context | error]

groups:
  - id: g1
    label: "Panel title"
    type: [outer_panel | inner_panel | swimlane | soft_region]
    children: [n1, n2, ...]

Writing this out is an internal planning step — clarify the structure in your own reasoning before committing to XML. After writing the DiagramSpec, proceed immediately to Step 3 without waiting for user confirmation. Read references/pattern-library.md for layout rules per pattern type.

Language consistency: Write the DiagramSpec — and all node labels, titles, and edge labels in the final XML — in the same language the user used. If the user wrote in Chinese, the diagram text should be Chinese too. A diagram whose labels match the user's language feels natural and avoids the jarring effect of mixed-language visuals.

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Step 3: Generate draw.io XML

Canvas setup

<mxGraphModel background="#F2EFE8" grid="0" tooltips="0" connect="0" arrows="0" fold="0" page="0" pageScale="1" pageWidth="1654" pageHeight="1169" math="0" shadow="0">
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- all cells go here with parent="1" (or parent="container_id" if nested) -->
  </root>
</mxGraphModel>

Use background="#F2EFE8" (warm canvas) for most diagrams. Use background="#FFFFFF" only for very minimal, sparse diagrams with few elements.

Title

<mxCell id="title" value="Your Diagram Title" style="text;html=1;strokeColor=none;fillColor=none;align=center;verticalAlign=middle;whiteSpace=wrap;overflow=hidden;fontStyle=1;fontSize=32;fontColor=#1F1F1C;" vertex="1" parent="1">
  <mxGeometry x="80" y="40" width="1200" height="50" as="geometry"/>
</mxCell>

Node style strings by semantic type

Apply these styles based on the semantic role, not just aesthetics. The color encodes meaning.

| Semantic type | draw.io style | |---|---| | Primary / Neutral | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#E6E2DA;strokeColor=#8C867F;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Secondary / Context | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#EAF4FB;strokeColor=#6FA8D6;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Tertiary / Control | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#EEEAF9;strokeColor=#9A90D6;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Start / Trigger | rounded=1;whiteSpace=wrap;arcSize=50;fillColor=#F8E9E1;strokeColor=#D88966;strokeWidth=1.8;fontColor=#D88966;fontSize=20;fontStyle=1; | | End / Success | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#CFE8D7;strokeColor=#71AE88;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Warning / Reset | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#F3E4DA;strokeColor=#C88E6A;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Decision | rhombus;whiteSpace=wrap;fillColor=#E6D7B4;strokeColor=#BFA777;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | AI / LLM | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#D7E6DC;strokeColor=#7FB08F;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Inactive / Disabled | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#EFECE6;strokeColor=#B4AEA6;strokeWidth=1.8;fontColor=#7A756E;fontSize=20; | | Error | rounded=1;whiteSpace=wrap;arcSize=10;fillColor=#F8DFDA;strokeColor=#D96B63;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Pill label | rounded=1;whiteSpace=wrap;arcSize=50;fillColor=#FAF8F4;strokeColor=#8C867F;strokeWidth=1.8;fontColor=#2D2B28;fontSize=20; | | Code/evidence block | rounded=1;whiteSpace=wrap;arcSize=6;fillColor=#EEF3F7;strokeColor=#B7C9D8;strokeWidth=1.5;fontColor=#44515C;fontSize=20;align=left; |

For semantic meaning of each type, read references/color-palette.md → Semantic Mapping Rules section.

Container / panel styles

All container styles include html=1; so that the value attribute can contain HTML. Use a <font> tag in the value to control the label font size (typically 2–4px larger than the fontSize in the style string, for visual hierarchy).

Outer panel (large system boundary):

rounded=1;whiteSpace=wrap;arcSize=4;fillColor=#FAF8F4;strokeColor=#8C867F;strokeWidth=2;fontSize=18;fontStyle=1;fontColor=#5F5A54;swimlane;startSize=63;horizontal=1;html=1;

value: <font style="font-size: 22px;">Panel Title</font>

Inner panel (subsystem or grouping):

rounded=1;whiteSpace=wrap;arcSize=6;fillColor=#FAF8F4;strokeColor=#8C867F;strokeWidth=1.8;fontSize=16;fontStyle=1;fontColor=#5F5A54;swimlane;startSize=50;horizontal=1;html=1;

value: <font style="font-size: 20px;">Panel Title</font>

Soft region (dashed grouping, no strong boundary):

rounded=1;fillColor=#F6F4EE;strokeColor=#B9B3AB;strokeWidth=1.5;dashed=1;dashPattern=6 6;fontSize=16;fontColor=#7A756E;html=1;

value: <font style="font-size: 18px;">Region Label</font>

Example XML for an outer panel:

<mxCell id="panel_server" parent="1" style="rounded=1;whiteSpace=wrap;arcSize=4;fillColor=#FAF8F4;strokeColor=#8C867F;strokeWidth=2;fontSize=18;fontStyle=1;fontColor=#5F5A54;swimlane;startSize=63;horizontal=1;html=1;" value="&lt;font style=&quot;font-size: 22px;&quot;&gt;Panel Title&lt;/font&gt;" vertex="1">
  <mxGeometry x="580" y="110" width="480" height="920" as="geometry"/>
</mxCell>

Children of containers use parent="container_id" and coordinates relative to the container.

Connector styles

The single most important style rule: all arrows use open chevron arrowheads.

endArrow=open;endSize=14;

This is what gives Anthropic diagrams their clean, editorial look. Never use filled/block arrowheads.

All connectors also use edgeStyle=orthogonalEdgeStyle — this makes lines route with right-angle bends and gives the diagram a clean, structured feel. Combined with rounded=1, the corners are softened into smooth curves rather than hard 90° turns.

| Connector type | Full style | |---|---| | Primary flow | endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#7A756E;strokeWidth=1.8;rounded=1;exitX=1;exitY=0.5;entryX=0;entryY=0.5; | | Optional / inferred | endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#9A948C;strokeWidth=1.6;rounded=1;dashed=1;dashPattern=6 6; | | Feedback loop | endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#8E8982;strokeWidth=1.8;rounded=1;curved=1; | | Human override | endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#D88966;strokeWidth=1.8;rounded=1;dashed=1;dashPattern=6 6; | | Context / support | endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#7FB08F;strokeWidth=1.8;rounded=1; | | Error path | endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#D96B63;strokeWidth=1.8;rounded=1; |

Every edge cell must have a child geometry element — never self-close:

<mxCell id="e1" edge="1" source="n1" target="n2" style="endArrow=open;endSize=14;edgeStyle=orthogonalEdgeStyle;strokeColor=#7A756E;strokeWidth=1.8;rounded=1;" parent="1">
  <mxGeometry relative="1" as="geometry"/>
</mxCell>

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Step 4: Layout rules

These rules keep diagrams feeling calm and well-composed:

• Node spacing: minimum 80px horizontal gap between adjacent nodes; 60px vertical gap
• Recommended horizontal pitch: 200px center-to-center for workflow steps
• Recommended vertical pitch: 120px center-to-center for parallel elements
• Canvas padding: 60px around the outermost content
• Grid alignment: snap all positions to multiples of 10
• Node size: standard nodes 140×60 to 180×70; wide containers 300–600+; title bar height 40
• Keep layout flat: max 3 nesting levels; prefer whitespace over extra containers

For pattern-specific layout rules (swimlane lane widths, comparison panel sizing, fan-out spacing, etc.), read references/pattern-library.md → the relevant pattern section.

Outer border

Every diagram gets a single outer border — a thin rounded rectangle that frames the entire composition (title + all content). This gives the diagram a poster-like finish and makes the whitespace feel intentional rather than accidental.

• Place this cell first in the XML, before all other nodes, so it renders behind everything
• x=20, y=20; width = pageWidth − 40 (→ 1614 for the standard 1654px canvas)
• Height: extend ~40px below the lowest node — snug enough to feel cohesive, loose enough to breathe
• Style: subtle warm stroke, no fill (the canvas background shows through)

<mxCell id="border" value="" style="rounded=0;arcSize=3;fillColor=none;strokeColor=#B9B3AB;strokeWidth=1.5;pointerEvents=0;" vertex="1" parent="1">
  <mxGeometry x="20" y="20" width="1614" height="1000" as="geometry"/>
</mxCell>

Adjust height so it ends roughly 40px below the bottom-most element. pointerEvents=0 keeps it non-interactive so users can click through it in draw.io.

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Step 5: Write and open

1. Write the complete XML to a descriptive .drawio file in the current working directory.
   • Filename: lowercase with hyphens, e.g., agent-loop.drawio, context-engineering.drawio
2. Open the file: start <filename>.drawio (Windows) or open <filename>.drawio (macOS)

If the user asks for PNG/SVG export:

"C:\Program Files\draw.io\draw.io.exe" -x -f png -e -b 20 -o output.drawio.png input.drawio

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Quality checklist

Before finalizing the XML, verify:

• [ ] Outer border present (id="border", first cell in XML, x=20 y=20, width=1614, height covers all content + 40px)
• [ ] Title is large (fontSize≥28), bold, dark (#1F1F1C), horizontally centered
• [ ] Canvas background set (background="#F2EFE8" in mxGraphModel)
• [ ] Every arrow uses endArrow=open;endSize=14
• [ ] Node colors follow semantic meaning, not decoration
• [ ] Main flow path is visually dominant within 3 seconds
• [ ] No more than 4 semantic accent colors in one diagram
• [ ] Every edge has <mxGeometry relative="1" as="geometry"/>
• [ ] All coordinates are multiples of 10
• [ ] No -- inside XML comments (invalid XML)
• [ ] Special characters escaped: & < >

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Reference files

• references/color-palette.md — Full semantic color rules, text hierarchy, container specs, background values, geometry tokens. Read when you need to choose colors or verify a semantic mapping.
• references/pattern-library.md — 12 diagram patterns with layout rules, anti-patterns, and combination rules. Read when the pattern choice is ambiguous or the layout needs fine-tuning.