Skill: SVG Theme System (Selectable + Customisable)

Scope

This Skill is about making SVG output:

• Consistent across diagrams
• Easy for agents to generate and evolve
• Themeable (multiple looks) without hand-editing 200 fills/strokes

It covers two practical approaches:

1. Build-time theming: generate per-theme SVG variants (best for <img src="..."> usage)
2. Runtime theming: CSS variables inside inline SVG (best for apps that inline SVG markup)

Inputs

• Target embedding mode:
  • Static: docs / <img> / GitHub rendering
  • Inline: injected SVG markup (e.g., in a UI control)
• Theme set (start with 2):
  • obsidian (industrial luxury)
  • white-leather (light)
• Constraints: readability, contrast, collision-free

Procedure

1) Pick your pipeline

• If the SVG is loaded as a file (image/object): choose build-time theming.
• If the SVG is inlined into HTML (string/DOM): runtime theming is possible.

2) Define a theme token schema (keep it small)

Recommended minimum tokens:

• background.primary, background.secondary
• surface.card, surface.border
• text.primary, text.secondary, text.muted
• accent.primary, accent.gold
• status.active, status.planned, status.error, status.warning
• strokeWidth.normal, strokeWidth.emphasis
• Typography: font.sans, font.serif, font.mono

Rule: Don’t invent per-diagram tokens. Reuse the schema.

3) Apply the tokens consistently

Use tokens for:

• Fills (backgrounds/panels)
• Strokes (borders/connectors)
• Text colors
• Highlight glows/filters

Avoid:

• Inline hardcoded colors repeated across nodes

4) Theme selection patterns

A) Build-time (recommended default)

• Generator accepts --theme <name>.
• It outputs diagram.<theme>.svg (or into theme folders).

This works everywhere, including <img> embedding and markdown.

B) Runtime (inline SVG only)

• Put a <style> block inside <defs> that defines CSS variables.
• Reference them in attributes (e.g. fill="var(--svg-bg)").

Important: runtime theming will not work for every renderer (depends on how SVG is embedded).

5) Agent-efficient iteration loop

When using agents to produce or modify SVGs:

1. Structure/layout first (use JSON/plan)
2. Generate via templates (MCP svg tools or generator script)
3. Validate collisions (tools are your eyes)
4. Fix + revalidate until clean

Validation

• node tools/dev/svg-collisions.js <file> --strict (pass: zero 🔴 HIGH)
• node tools/dev/svg-validate.js <file> (pass: zero errors)

Escalation / Research request

Ask for dedicated work if:

• You need a new reusable template for svg_stamp/svg_create.
• You need a shared “theme registry” used by both generator scripts and the SVG MCP server.

References

• SVG methodology: docs/guides/SVG_CREATION_METHODOLOGY.md
• SVG MCP tools: docs/guides/SVG_TOOLING_V2_QUICK_REFERENCE.md
• WLILO style: docs/guides/WLILO_STYLE_GUIDE.md
• Collision tool: tools/dev/svg-collisions.js