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PET BRAINS

// tool · 02 / 03

Design-builder

Production-grade UI without the AI slop. Design plugin for Claude Code with 4 commands covering setup, create, improve, and review.

// what is it

A design plugin for Claude Code that produces distinctive, production-grade UI.

Design-builder is a Claude Code plugin that turns Claude into a design partner. Four user-facing commands cover the pipeline end to end: /setup builds the design system from anchored references, /create generates page or screen specs, /improve audits and fixes existing UI, /review runs a strict critique against accessibility, motion, anti-patterns.

Backed by a designlib catalog of 400+ inspiration pages, anti-pattern filters, motion principles from working designers, and the iOS HIG. Web and iOS supported. Open source, MIT-licensed.

// the problem

Generic AI workflows produce generic UI.

Cyan-on-dark gradients, three-column feature card rows, gradient text, side-stripe alert callouts — the AI-tool visual default since 2023, regardless of brand. The agent has been trained on the same Dribbble shots as everyone else.

Design-builder fights this through three layers: a knowledge base (designlib references, HIG, motion principles) that gives the agent specific source material, design filters (direction, dials, anti-patterns, distinctiveness gate) that gate every output, and command scenarios (setup → create → improve → review) that orchestrate the layers.

The result is interfaces that read as deliberate brand choices — not as the AI default.

// how it works

Four commands. One pipeline.

  1. // 01

    /setup — build the design system.

    Anchored to inspiration references, palettes, font pairs from designlib. Outputs tokens.css, style-guide.md, content-library.md, an HTML preview. Direction is committed up front so every later command honors it.

  2. // 02

    /design_page or /design_screen — generate the spec.

    Spec-first: writes design/pages/<name>.md or design/screens/<name>.md with sections, content slots, tokens, animations, edge cases. No code emitted yet — the spec is the contract.

  3. // 03

    /build — write the code.

    Reads the spec, writes the production code in your stack (Astro, Next, SwiftUI, etc.). Anti-patterns are gated server-side; tokens come from tokens.css. Code is the output, not the input.

  4. // 04

    /improve and /review — keep it production-grade.

    /improve audits and fixes existing UI against the system. /review runs a strict P0–P3 critique on composition, typography, color, accessibility, motion, AI-slop indicators. Both are gates on the road to ship.

// who it's for

Builders who ship UI, not just demos.

Design-builder is for builders who already use Claude Code (or Cursor/Copilot) for code, and who want the same agentic workflow for design — production-grade, not vibe-coded. Indie founders, senior frontend devs, designers who code.

Best fit: web (Astro, Next, Vite) and iOS (SwiftUI). Worst fit: Figma-only workflows where no code is being generated — the plugin's output is code, not Figma frames.

// compatibility

Compatibility

// get started

Install the plugin, run /setup.

Get notified when Design-builder ships a major update.