Visual Explainer

Generate self-contained HTML pages that explain systems, code changes, plans, data, and technical concepts visually. Use this skill for diagram requests, architecture overviews, diff/plan reviews, project recaps, comparison tables, slide decks, and any visual explanation.

Trigger and delivery rules

• Prefer an HTML page over terminal ASCII when the output is inherently visual.
• If a table would have 4+ rows or 3+ columns, render it as HTML and give only a short chat summary.
• Write files to ~/.agent/diagrams/ or the explicit eval output path. Use descriptive filenames.
• Open generated pages in the browser when running normally. In Pi package installs, use visual_explainer with prepare for planning/context and render only after the complete HTML document exists.
• The final page must be a complete self-contained HTML document, including embedded CSS and any needed JS.

Reference routing

Read only the references needed for the current output:

Need	Read
Text-heavy architecture/cards	./templates/architecture.html
Mermaid flowcharts, sequence, ER, state, class, C4, data flow	./templates/mermaid-flowchart.html, Mermaid sections in ./references/libraries.md
Data tables, comparisons, audits	./templates/data-table.html
Slide decks	./templates/slide-deck.html, ./references/slide-patterns.md
CSS layout, overflow, depth, collapsibles, SVG connectors, generated images	./references/css-patterns.md
Pages with 4+ major sections	./references/responsive-nav.md
Prose-heavy pages	“Prose Page Elements” in css-patterns.md, typography sections in libraries.md

Choose the representation

Content	Default representation
Flowchart, pipeline, state machine, decision tree	Mermaid
Sequence, ER/schema, class, C4, topology-focused architecture	Mermaid
Text-heavy architecture, module internals, implementation plans	CSS grid cards, optionally with a Mermaid overview
15+ element architecture	Hybrid: small Mermaid overview + CSS detail cards
Comparison/audit/status matrix	Semantic HTML <table>
Timeline/roadmap	CSS timeline
Dashboard/metrics	CSS grid + charts/KPIs
Slide deck	100dvh slides using slide template patterns

Mermaid invariants

• Use theme: 'base' with custom themeVariables matching the page palette.
• For complex diagrams use ELK layout when available.
• Never use bare <pre class="mermaid">.
• Use the canonical diagram-shell pattern from templates/mermaid-flowchart.html: .diagram-shell > .mermaid-wrap > .zoom-controls + .mermaid-viewport > .mermaid-canvas.
• Every Mermaid diagram needs zoom in/out/reset/expand controls, Ctrl/Cmd+scroll zoom, drag panning, and click-to-expand.
• Prefer flowchart TD for complex diagrams. Use LR only for simple 3–4 node linear flows.
• Use <br/> in quoted flowchart labels. Do not use escaped \n labels.
• Never define page-level .node; Mermaid uses it internally. Use namespaced page classes such as .ve-card.
• For 15+ elements, do not cram everything into one Mermaid diagram. Use the hybrid overview + cards pattern.

Layout and style invariants

• Use semantic HTML where it helps accessibility and copy/paste: <table>, headings, lists, <details>, captions.
• Use CSS custom properties for palette: --bg, --surface, --border, --text, --text-dim, and 3–5 accents.
• Pick a clear aesthetic direction before writing: blueprint, editorial, paper/ink, terminal, IDE-inspired, or data-dense.
• Avoid generic defaults: no body font that is only Inter, Roboto, Arial, Helvetica, or system-ui; no violet/fuchsia Tailwind-default accents as the main palette (#8b5cf6, #7c3aed, #a78bfa, #d946ef); no cyan+magenta+purple neon dashboard; no gradient-mesh blobs.
• Good font pair families: DM Sans + Fira Code; Instrument Serif + JetBrains Mono; IBM Plex Sans + IBM Plex Mono; Bricolage Grotesque + Fragment Mono; Plus Jakarta Sans + Azeret Mono.
• Good accent directions: terracotta+sage, teal+slate, rose+cranberry, amber+emerald, deep blue+gold.
• Prevent overflow: min-width: 0 on grid/flex children, overflow-wrap: break-word for long text, and scroll containers for wide tables/code.
• Do not set display: flex directly on <li> when list markers matter.
• Use depth sparingly: hero/elevated only for primary sections; flat/recessed for reference material.
• Use entrance/hover animation only when it clarifies hierarchy. Respect prefers-reduced-motion. Do not use continuous glow, pulse, or breathing effects on static content.

Slide deck mode

Use slides only when explicitly requested or when a command asks for slides. Slides are a different medium, not a paginated article:

• Each slide is one viewport (100dvh) with no page-level scrolling.
• Use larger type, fewer objects per slide, varied compositions, and visible navigation.
• Include slide nav chrome from slide-deck.html: prev/next controls, slide count, keyboard navigation, and carousel dots/indicators.
• Before writing HTML, inventory the source and map every source item to slides.
• Do not drop content to fit a fixed slide count. Add slides instead.
• Use the 10 slide types from slide-patterns.md: Title, Section Divider, Content, Split, Diagram, Dashboard, Table, Code, Quote, Full-Bleed.

Optional generated images

If surf is available, generated images may be embedded as base64 for hero banners, conceptual illustrations, or educational visuals. Skip images for data-heavy, structural, or Mermaid/CSS-suitable content. Pages must stand on CSS, typography, and diagrams without images.

Final checklist

Before delivery, verify:

• complete HTML document;
• output written to the requested path;
• no console errors when opened;
• no horizontal overflow at normal desktop width;
• fonts load with fallbacks;
• tables preserve rows/columns and wrap long text;
• Mermaid diagrams use diagram-shell with zoom/pan/expand;
• slides fit one viewport, include carousel dots, and preserve source coverage;
• visual hierarchy makes the main idea obvious in the first viewport;
• styling would still be recognizable if compared against a generic dark/violet template.