/design-system-builder

name: design-system-builder
description: Extract design systems from reference UI images and generate implementation-ready UI design prompts. Use when users provide UI screenshots/mockups and want to create consistent designs, generate design systems, or build MVP UIs matching reference aesthetics.

UI Designer

Overview

This skill enables systematic extraction of design systems from reference UI images through a multi-step workflow: analyze visual patterns → generate design system documentation → create PRD → produce implementation-ready UI prompts.

When to Use

• User provides UI screenshots, mockups, or design references
• Need to extract color palettes, typography, spacing from existing designs
• Want to generate design system documentation from visual examples
• Building MVP UI that should match reference aesthetics
• Creating multiple UI variations following consistent design principles

Workflow

Step 1: Gather Inputs

Request from user:

• **Reference images directory**: Path to folder containing UI screenshots/mockups
• **Project idea file**: Document describing the product concept and goals
• **Existing PRD** (optional): If PRD already exists, skip Step 3

Step 2: Extract Design System from Images

**Use Task tool with general-purpose subagent**, providing:

**Prompt template** from `assets/design-system.md`:

• Analyze color palettes (primary, secondary, accent, functional colors)
• Extract typography (font families, sizes, weights, line heights)
• Identify component styles (buttons, cards, inputs, icons)
• Document spacing system
• Note animations/transitions patterns
• Include dark mode variants if present

**Attach reference images** to the subagent context.

**Output**: Complete design system markdown following the template format

**Save to**: `documents/designs/{image_dir_name}_design_system.md`

Step 3: Generate MVP PRD (if not provided)

**Use Task tool with general-purpose subagent**, providing:

**Prompt template** from `assets/app-overview-generator.md`:

• Replace `{项目背景}` with content from project idea file
• The template guides through: elevator pitch, problem statement, target audience, USP, features list, UX/UI considerations

**Interact with user** to refine and clarify product requirements

**Output**: Structured PRD markdown

**Save as variable** for Step 4 (optionally save to `documents/prd/`)

Step 4: Compose Final UI Implementation Prompt

Combine design system and PRD using `assets/vibe-design-template.md`:

**Substitutions:**

• `{项目设计指南}` → Design system from Step 2
• `{项目MVP PRD}` → PRD from Step 3 or provided PRD file

**Result**: Complete, implementation-ready prompt containing:

• Design aesthetics principles
• Project-specific color/typography guidelines
• App overview and feature requirements
• Implementation tasks (multiple UI variations, component structure)

**Save to**: `documents/ux-design/{idea_file_name}_design_prompt_{timestamp}.md`

Step 5: Verify React Environment

Check for existing React project:

find . -name "package.json" -exec grep -l "react" {} \;

If none found, inform user:

npx create-react-app my-app
cd my-app
npm install -D tailwindcss postcss autoprefixer
npx tailwindcss init -p
npm install lucide-react

Step 6: Implement UI

Use the final composed prompt from Step 4 to implement UI in React project.

The prompt instructs to:

• Create multiple design variations (3 for mobile, 2 for web)
• Organize as separate components: `[solution-name]/pages/[page-name].jsx`
• Aggregate all variations in showcase page

Template Assets

assets/design-system.md

Template for extracting visual design patterns. Includes sections for:

• Color palette (primary, secondary, accent, functional, backgrounds)
• Typography (font families, weights, text styles)
• Component styles (buttons, cards, inputs, icons)
• Spacing system (4dp-48dp scale)
• Animations (durations, easing curves)
• Dark mode variants

Use this template when analyzing reference images to ensure comprehensive design system coverage.

assets/app-overview-generator.md

Template for collaborative PRD generation. Guides through:

• Elevator pitch
• Problem statement and target audience
• Unique selling proposition
• Platform targets
• Feature list with user stories
• UX/UI considerations per screen

Designed for interactive refinement with user to clarify requirements.

assets/vibe-design-template.md

Final implementation prompt template combining design system and PRD. Includes:

• Aesthetic principles (minimalism, whitespace, color theory, typography hierarchy)
• Practical requirements (Tailwind CSS, Lucide icons, responsive design)
• Task specifications (multiple variations, component organization)

This template produces prompts ready for UI implementation without further modification.

Best Practices

Image Analysis

• Read all images before starting analysis
• Look for patterns across multiple screens
• Note both explicit styles (colors, fonts) and implicit principles (spacing, hierarchy)
• Capture dark mode if present in references

Design System Extraction

• Be systematic: cover all template sections
• Use specific values (hex codes, px sizes) not generic descriptions
• Document the "why" for design choices when inferable
• Include variants (hover states, disabled states)

PRD Generation

• Engage user interactively to clarify ambiguities
• Suggest features based on problem understanding
• Ensure MVP scope is realistic
• Document UX considerations per screen/interaction

Output Organization

• Save design system with descriptive filename (based on image dir name)
• Save final prompt with timestamp for version tracking
• Keep all outputs in `documents/` directory for easy reference
• Preserve intermediate outputs for iteration

Example Usage

**User provides:**

• `reference-images/saas-dashboard/` (5 screenshots)
• `ideas/project-management-app.md` (project concept)

**Execute workfl