StylePrint

StylePrint is a prototype for extracting design facets from UI reference screenshots, mixing style choices across references, and generating React + Tailwind UI code.

The app is split into a Vite React frontend and a Fastify TypeScript backend.

Quick Links

• Production website: https://style-print.vercel.app/
• Local web app: http://localhost:5173
• Local API health check: http://localhost:4000/health

What It Does

StylePrint helps turn visual UI references into reusable generation inputs:

• Upload UI reference screenshots.
• Extract design facets such as color, typography, layout, spacing, component style, and mood.
• Choose or recommend recipes that combine facets from multiple references.
• Evaluate intent coherence, conflicts, and possible repairs.
• Generate React + Tailwind UI code through v0.
• Build preview artifacts and compare generated output against the intended style.

Project Structure

apps/
  web/        Vite + React + TypeScript frontend
  api/        Fastify + TypeScript API server
packages/
  shared/     shared frontend/backend TypeScript types
data/         local JSON storage
public/
  uploads/    uploaded reference images

Development Workflow

Branches follow this flow:

main -> dev -> feature/*

• main: stable branch.
• dev: integration branch for active development.
• feature/*: feature or issue-specific work.

Recommended workflow:

1. Create or identify the GitHub Issue for the task.
2. Create a feature/* branch from dev.
3. Implement the feature.
4. Run npm run typecheck.
5. Run npm run build when the change affects broader frontend/backend behavior.
6. Open a PR from feature/* to dev.
7. Keep planning docs, weekly deliverables, and agent workflow notes in the GitHub Wiki.

Local Setup

Install dependencies and create a local environment file:

cd /Users/Owner/hcclab/style-print-jung
npm install
cp .env.local.example .env.local

Add real API keys to .env.local in the project root.

Start both the frontend and backend:

npm run dev

Then open the web app and check the API:

open http://localhost:5173
curl http://localhost:4000/health

You can also run the API and web app in separate terminals:

npm run dev:api

npm run dev:web

Environment Variables

The local environment file lives at:

/Users/Owner/hcclab/style-print-jung/.env.local

Create it from the example file if it does not exist:

cp .env.local.example .env.local

Expected values:

OPENAI_API_KEY=sk-...
OPENAI_MODEL=gpt-4.1-mini
OPENAI_JUDGE_MODEL=gpt-4.1-mini
V0_API_KEY=...
V0_MODEL=v0-mini
API_PORT=4000
WEB_ORIGIN=http://localhost:5173
VITE_API_BASE_URL=

OPENAI_API_KEY and V0_API_KEY are required. If either key is missing, or if an external API call fails, the relevant API request fails instead of falling back to mock data.

OPENAI_JUDGE_MODEL is optional. Use it to separate the coherence judge model from the main OPENAI_MODEL; if it is not set, the API uses OPENAI_MODEL.

WEB_ORIGIN accepts multiple frontend origins separated by commas. For example:

WEB_ORIGIN=https://style-print.vercel.app,https://style-print-git-dev.vercel.app

Core Flow

1. The web app uploads reference images as multipart/form-data.
2. The API stores images in public/uploads and records file URL, MIME type, width, and height metadata in data/references.json.
3. The API extracts palette, semantic color roles, and contrast information with sharp and rule-based color analysis.
4. The OpenAI Responses API analyzes typography, layout, spacing, component style, and mood keywords from the same reference.
5. Recipe recommendation or manual recipe selection creates an IntentSpec; selected facet provenance, source mood, and confidence are normalized into styleContext.
6. The API runs rule-based coherence evaluation and can add an OpenAI judge evaluation in off, shadow, or primary mode.
7. The UI generation brief, screen plan, and variant count are saved in IntentSpec.generationBrief and passed into the v0 prompt.
8. v0 generation runs as an async job. /api/generate/v0 returns a job ID, and the web app polls /api/generate/jobs/:jobId for generated code and preview URLs.
9. The API builds preview artifacts locally and stores a Playwright screenshot when available.
10. OpenAI audit extracts facets from generated code and stores an intent comparison report with provenance badges.

API Routes

Endpoint	Method	Description
/health	GET	Check API status.
/uploads/:filename	GET	Serve uploaded images.
/generated-previews/:previewId/:filename	GET	Serve generated preview artifact files.
/api/references/upload	GET	List references.
/api/references/upload	POST	Upload a multipart reference image.
/api/references/upload?id=...	DELETE	Delete a reference.
/api/facets/extract	POST	Extract facets from a reference.
/api/intents/create	POST	Create an intent from a selected recipe.
/api/recipes/recommend	POST	Recommend recipes from a facet pack.
/api/intents/evaluate	POST	Evaluate intent coherence and conflicts, then save repair suggestions. judgeMode can be off, shadow, or primary.
/api/intents/apply-repair	POST	Apply a repair suggestion.
/api/coherence/feedback	POST	Save feedback for coherence judge results.
/api/generate/v0	POST	Create a v0 UI generation job. Only single mode is currently supported.
/api/generate/jobs/:jobId	GET	Read generation job status and result.
/api/preview/build	POST	Build preview artifacts from generated code.
/api/audit/analyze	POST	Audit generated code. If generatedCodeId is provided, link the audit to that report.

Implementation Notes

• Reference extraction uses rule-based color analysis and OpenAI LLM analysis for typography, layout, spacing, component style, and mood.
• LLM prompts receive palette and asset dimensions so they do not over-infer layout from non-UI assets.
• v0 prompts receive normalized facets, exact palette usage, source mood/confidence, user brief, screen plan, and variant count.
• v0 generation currently produces one default-export React component.
• GenerationMode still includes staged, but the server does not implement staged generation yet. /api/generate/v0 rejects staged requests with 400.
• Missing API keys or failed external API calls do not produce demo/mock results.

Verification

Run focused checks during development:

npm run typecheck
npm run test
npm run build
npm run regression:intents
npm run agreement:coherence

npm run build runs backend/frontend type checks and then builds the Vite app for production.

npm run regression:intents compares saved intent coherence reports for regressions.

npm run agreement:coherence outputs a Markdown report comparing rule evaluator results, OpenAI judge results, and human feedback expected scores.

Run the deployment smoke check with:

npm run smoke:deploy

To smoke check specific deployed URLs, pass them as environment variables:

SMOKE_API_BASE_URL=https://style-print-jung-api.up.railway.app \
SMOKE_WEB_BASE_URL=https://style-print.vercel.app \
npm run smoke:deploy

Current Limitations

• OpenAI and v0 API calls require valid API keys.
• Staged generation is represented in shared types but is not implemented on the server.
• Storage is JSON-file based; multi-user or production deployments need a database and durable object storage such as SQLite/PostgreSQL plus S3/R2.
• Authentication and per-user data isolation are not implemented yet.