Developer Builds Pencil-Sketch Architecture Diagram Skill With Claude Code, Complete With Self-Checking
himanshu13ps · reddit · 2026-10-12
Developer himanshu13ps released penciled, an agent skill that turns a short JSON description into architecture diagrams drawn like a 2B pencil on paper — tapered strokes, hatched shading, overshooting corners, handwritten labels — for quick whiteboard-style design docs.
The whole project was built with Claude Code: it wrote the renderer, layout engine, validator and tests from the author's milestone plan, and checked the pencil look by rendering screenshots in a headless browser until each stage was signed off.
Its standout feature is self-checking: before drawing, it lays out the diagram exactly as it will be drawn and warns about crossing arrows, overlaps and crowded labels, with a suggested fix for each, so the agent can correct its own diagram before you see it.
- Install: npx skills add himanshu13ps/penciled (works with Claude Code, Cursor, Codex and other skill-reading agents)
- Usage: just ask it to sketch a repo's architecture as a hand-drawn diagram
- Outputs SVG, PNG, or a single offline HTML page with redraw, paper/pencil switching and zoom
- No dependencies beyond Node 18; free, MIT licensed
- A browser playground is available for trying it without installing
Code and playground are open source.
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