Create diagrams and visual explanations with iterative render-and-check workflow. Use when asked to 'create a diagram', 'Venn diagram', 'flow chart', 'architecture diagram', 'visualize this'. Renders SVG to PNG, self-critiques using CRAP principles, iterates until right. Composes with brand skills for styling. (user)
Overview
# Diagramming
Create conceptual charts and diagrams as SVG, render to PNG, self-critique, iterate, and show user.
When to Use
Conceptual diagrams (Venn, flow, architecture)
Data charts (line, bar, area)
Visual explanations for slides or documents
When NOT to Use
Hero images or photorealistic content (use picture skill)
Simple text formatting (markdown suffices)
Screenshots or screen mockups (different tools)
Workflow
1. Understand the Content
User typically provides:
Structure β "boxes connected by arrows", "Venn with overlap"
Content β the actual text/data to include
Purpose β the message or insight
Clarify these before drawing. The structure is theirs, the execution is yours.
2. Apply Brand (if applicable)
If a brand skill exists (e.g., itv-brand), read its specs for:
Color palette
Typography
Visual principles
If no brand specified, use sensible defaults:
Dark background (#1a1a2e or similar)
Clear hierarchy (see Contrast below)
3. Create SVG
Canvas: 1280Γ720 (16:9) default. Brand skill may override.
```xml
```
For human-editable SVGs: Structure multi-line text as siblings in one transform group:
```xml
Line One
Line Two
```
This keeps lines together as one selectable object in editors like Inkscape. (Note: Affinity breaks this apart on import β see references/svg-interop.md.)
CRITICAL: Never create separate unlinked elements for lines that belong together semantically. If "New stories / to tell" is one label, it's one group β always. Ungrouped lines become editing nightmares.
Note: sips is faster but doesn't support markers/arrows.
5. Self-Critique (CRAP + Composition)
Read the PNG and critique against CRAP principles before showing user:
Proximity β Are related items grouped?
Labels adjacent to what they describe (not 300px away in a separate column)
Annotations should be close enough that the eye doesn't have to hunt
More space between groups than within groups
White space organized, not scattered
Alignment β Do elements connect visually?
Every element aligns with something else
One dominant alignment system
If annotations are in a column, align them to ONE x-coordinate (ragged = amateur)
Strong invisible lines across the canvas
Cross-canvas alignment creates unity even between unrelated elements
Repetition β Is styling consistent?
Similar elements styled identically
Limited color palette, reused systematically
Clear visual rhythm
Consolidate font sizes to 3-4 levels maximum
Contrast β Is hierarchy clear?
Title largest, then highlighted element, then content
Primary data stands out from secondary
No "wimpy" differences β all contrasts are bold
Check contrast at smaller sizes β problems emerge
Composition Check β After CRAP, step back and ask:
Is the composition centered on the canvas? (Calculate, don't eyeball)
Is whitespace balanced left/right, top/bottom?
Are there orphan elements with no visual relationship to anything?
Centering calculation:
```
left_edge = leftmost content x-coordinate
right_edge = rightmost content x-coordinate
content_center = (left_edge + right_edge) / 2
offset = canvas_center - content_center
# Shift everything by offset
```
See references/design-principles.md for detailed interventions.
6. Reduced Size Check
View the PNG at 50-75% size (or squint). Problems that hide at full size emerge:
Centering issues become obvious
Competing elements reveal themselves
Hierarchy flattens β is the important thing still prominent?
Low contrast text disappears
If something looks wrong small, it IS wrong.
7. Fix and Re-render
If issues found, fix and render again. Iterate until satisfied. Only then show user.
Common fixes:
Centering off β calculate offset, shift all elements
Annotations too far β move closer, or put inside elements
Orphan element β add connector line or align to something
Low contrast β boost to #e2e8f0 minimum for text on dark backgrounds
8. Completeness Check
Before showing user, ask: what's missing from the domain? You're visualising someone's mental model β have you captured all the key elements they'd expect to see? If the diagram is about "data partnerships" and you only listed two when there are three, the user will notice. This isn't about design; it's about content accuracy.
9. Show User
```bash
open -a "Google Chrome" /tmp/chart.png
```
Or copy to Desktop if user needs the file.
Design Principles
Hierarchy
Title > Highlighted element > Content. The title is largest. The key insight (e.g., Venn intersection) is second. Everything else supports these.
Containment
In Venn diagrams, intersection text should be visually contained within the overlap shape. Each piece of content should be unambiguously inside its region.
Territory Clarity
No straddling, no ambiguity about "which side does this belong to?" Content occupies clear territory.
Labels Don't Touch Lines
Circle labels, box labels β keep clear space from edges. Position labels at "clock positions" (10 o'clock, 2 o'clock) rather than centered above.
Fill the Space
Chart area should use ~80% of canvas
"Fill" means centered and balanced, not just "big enough"
If there's empty space at bottom, elements are undersized or poorly positioned
Scale elements uniformly to fill β never stretch text (aspect ratio is sacred)
Scatter, Don't Stack
When placing multiple detail items within a region (e.g., items inside a Venn circle), scatter them organically to fill the territory. Don't default to neat vertical stacks or bullet-list layouts β that's document thinking, not visual thinking. Let items breathe and occupy the space naturally. Stacking looks rigid; scattering looks designed.
Display Text Capitalisation
Labels and titles get consistent Title Case capitalisation.
Label Specificity
Review labels for specificity before finalising. Bare nouns often need modification to land:
"Naming" β "Consistent Naming"
"SME-friendly" β "SME-friendly tools"
"Models" β "Better predictive models"
Ask: would someone unfamiliar with the context understand what this means? If not, add the adjective.
Chesterton's Fence
Before removing any element, ask: "What job is this doing?"
Axis labels frame conceptual space (X vs Y dimensions)
Annotations provide meaning, not just labels ("This ad led to this click" β "Last-click")
Width indicators reinforce messages the visual implies
Key/legend panels group meta-information
Don't mistake "explanation" for "noise"
Respect the Metaphor
Visual metaphors have rules. Breaking them breaks comprehension:
Ladder: rungs go INSIDE the rails, not wider than them
Venn: content belongs unambiguously in one region
Flow: arrows point in direction of flow
Tree: children below parents
If your visual breaks the metaphor's rules, the viewer's mental model breaks.
Less Is More (Especially Overlaps)
Not every region needs a label. In Venn diagrams, if an overlap's meaning is self-evident from the surrounding content, leave it empty. Labelling everything creates noise. The unlabelled center can be more powerful than a forced "synergy" label. Ask: does this label add meaning, or am I labelling because I feel I should?
No Orphan Elements
Everything needs a visual relationship to something else:
If a callout box floats alone, connect it (line, alignment, proximity)
Elements without relationships look like mistakes
Even "independent" items should align with something
Key/Legend Placement
Hierarchy of preferences:
Best: No key needed β visual is self-explanatory
Acceptable: Contained key panel β all meta-info grouped in one area
Worst: Scattered meta-info β bits floating in different corners
If you need a key, contain it. If you're adding labels to explain what colors mean, the colors might not be working.
Key Specs
| Element | Size | Notes |
|---------|------|-------|
| Title | 36-40px | Largest, top hierarchy |
| Highlighted text | 24-28px | Second hierarchy |
| Labels | 20-24px | Circle/region labels |
| Content text | 18-20px | Inside regions |
| Strokes | 3-4px | Circle outlines, connectors |
Composing with Brand Skills
When a brand skill exists:
Read its brand-guide.md for colors, fonts, specs
Apply those specs to your SVG
Brand skill may specify different canvas size
Example: For ITV-branded charts, also invoke the itv-styling skill.
Anti-Patterns
| Pattern | Problem | Fix |
|---------|---------|-----|
| Skip self-critique | Quality issues persist | Always render and check before showing user |
| Low contrast text | Illegible on projection | White/near-white on dark, test at 50% zoom |