Stack

Preferred technologies for new projects. See versions.md for minimum version requirements.

Foundation (MUST)

Every project uses these. Non-negotiable.

Technology	Purpose	Notes
Next.js	Framework	App Router, Turbopack, proxy.ts. See nextjs.md
React	UI	ref-as-prop, use() hook, useActionState. See versions.md
TypeScript	Language	Strict mode. See typescript.md
Tailwind CSS	Styling	CSS-first config, @theme, @source. See tailwind.md
Zod	Validation	Schema validation for forms, env, API boundaries
pnpm	Package manager	Not npm or yarn
Biome + Ultracite	Formatting/linting	Single tool, Rust-based. See code-style.md
Vercel	Hosting	Deployment, preview environments, cron jobs
TanStack React Query	Server state	MUST for all client-side data fetching
Vercel AI SDK 6	AI integration	MUST for any AI features. See ai-sdk.md for v6 API changes. Run /arc:ai for guided setup

Default (SHOULD)

Strong preference. Use unless there's a specific reason not to.

Database

• Neon — Serverless PostgreSQL with branching and instant scaling
• Drizzle ORM — Type-safe, SQL-like syntax, db:push workflow for development

Auth

• Clerk — Pre-built UI components, social logins, organizations, webhook sync

API

• tRPC 11 — Typesafe client data layer. See api.md for conventions.
• OpenAPI 3.1 — Specification for HTTP APIs. Generate from code, never hand-write.

CLI

• Commander + Ink — Dual-mode CLI (scripted + interactive). See cli.md for conventions.

UI

• shadcn — Scaffolded components copied into the project, not a dependency
• Radix UI — Accessible primitives for dialogs, dropdowns, popovers, etc.
• CVA (class-variance-authority) — Component variant definitions
• Motion — Animation library, respects prefers-reduced-motion
• Alternative: Base UI as an unstyled primitive option

State

• nuqs — Type-safe URL search params. Use for filters, tabs, pagination, expanded panels. URL is the source of truth.
• Zustand — Global client state (persistence, selectors, devtools)

Forms

• Native <form> + Zod for simple forms
• React Hook Form + Zod for complex multi-step forms

Code Quality

• Husky + lint-staged — Pre-commit hooks
• Playwright — E2E testing
• Vitest — Unit testing

Contextual (MAY)

Proven options for specific needs. Install when the project requires them.

Edge / Workers

• Cloudflare Workers — Edge compute for API gateways, proxies, and lightweight services. See cloudflare-workers.md
• Hono — Lightweight web framework for Workers (alternative to raw fetch handler)

Monorepo

• Turborepo — When the app demands multiple packages/apps, or could demand it in the near future

Analytics & Monitoring

• PostHog — Product analytics, user identification, feature flags
• Sentry — Error tracking, source maps, session replay

Email

• Resend — Transactional email delivery
• React Email — Email templates as React components

Files

• UploadThing — Type-safe file upload routers

AI

• OpenRouter — Multi-model API access (Claude, Gemini, etc.). Use with AI SDK via @openrouter/ai-sdk-provider
• fal.ai — Image generation (GPT-Image, Flux, etc.)
• Voyage AI — Embeddings for semantic search and RAG

Native

• React Native — Cross-platform native apps
• Expo — Managed workflow, OTA updates, build service
• For React Native patterns, install the vercel-react-native-skills skill

Rejected Alternatives (NEVER)

When AI agents or contributors suggest these, redirect to the preferred option.

Never	Use Instead	Why
Prisma	Drizzle	Lighter, SQL-like, better serverless perf
ESLint / Prettier	Biome	Single tool, faster, zero config with Ultracite
npm / yarn	pnpm	Faster installs, strict dependency resolution
NextAuth / Auth.js	Clerk	Pre-built UI, managed infrastructure, orgs
Redux / MobX	Zustand (or server state)	Simpler API, smaller bundle, no boilerplate
Styled Components / CSS Modules	Tailwind	Utility-first, no runtime cost, design tokens via CSS
Jest	Vitest	Faster, ESM-native, compatible API
Cypress	Playwright	Faster, multi-browser, better DX