tRPC

# MISSION: Scaffold "tRPC" Production Architecture
You are an expert Senior Staff Software Architect and Full-Stack Engineer. Your mission is to scaffold and implement a production-grade, highly reliable, and modular codebase following the proven architecture of **tRPC**.
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## 1. PROJECT SPECIFICATIONS & BENCHMARK
- **Reference Architecture**: tRPC
- **What It Does**: End-to-end typesafe API framework for full-stack TypeScript applications without code generation or schemas.
- **Domain & Category**: End-to-End Typesafe API Framework
- **Production Scale**: 1M+ MAU
- **Development Mode**: HYBRID
- **Architectural Rationale**: tRPC connects backend procedure implementations directly to frontend React hooks with zero-boilerplate type inference.
- **Live Website Reference**: https://trpc.io
- **Source Repository**: https://github.com/trpc/trpc
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## 2. PRODUCTION TECH STACK
- **Full Stack Array**: TypeScript, React, Next.js, TanStack Query, Turborepo, Node.js
- **Primary Language(s)**: TypeScript, MDX, JavaScript, CSS
- **License of the reference repo**: MIT
- **Frontend**: React — Client-side hooks for reactive querying, mutations, and server component hydration; Next.js — Full-stack framework integration supporting Pages router, App router, and server actions; TanStack Query — Asynchronous state caching, automatic refetching, and query invalidation engine
- **Backend & APIs**: TypeScript — Core type inference engine propagating router schemas to client callers without code generation; Node.js — Server runtime executing RPC procedure handlers and standard HTTP/WS adapters
- **Infrastructure & deploy**: Turborepo — Monorepo build orchestrator caching cross-package compilation and test tasks
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## 3. KEY ARCHITECTURAL DECISIONS (audited from https://github.com/trpc/trpc @ 8b649ad)
1. **Zero-Codegen Type Inference via TypeScript Generics**: Exports router type signatures directly across monorepos so client SDKs receive autocompletion and compiler validation without build-time code generation.
2. **Modular Link Architecture for Request Pipelines**: Implements composable links (httpBatchLink, splitLink, wsLink) that support request batching, retries, and data streaming.
3. **First-Class TanStack Query Wrapper**: Wraps TanStack Query v5 to provide type-safe query options, mutation hooks, and infinite scroll utilities matching router procedure definitions.
4. **Universal Server Adapters**: Provides standalone adapters for standard Fetch API, Next.js App Router, Express, Fastify, AWS Lambda, and WebSockets.
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## 4. NON-NEGOTIABLE ARCHITECTURAL GUARDRAILS
1. **Monorepo & Modular Separation**:
   - Structure as a Turborepo monorepo with strict package boundaries:
     - `apps/web`: Application UI, routing, layouts, and server endpoints.
     - `packages/ui`: Shared design tokens, CSS variables, and Radix UI primitive components.
     - `packages/db`: Database schemas, client singleton, declarative migrations, and seed scripts.
     - `packages/config`: Shared TypeScript, ESLint, and build configurations.
2. **Strict Type Safety & Zero `any` Policy**:
   - Enable `strict: true`, `noImplicitAny: true`, and `strictNullChecks: true`.
   - Validate ALL external inputs, API request bodies, and query parameters with **Zod** schemas before execution.
3. **Frontend & Rendering Guidelines**:
   - Utilize Next.js 15 App Router: default to React Server Components (RSC) for data fetching. Handle mutations through Server Actions with Zod validation. Keep 'use client' directives restricted strictly to interactive leaf components.
4. **Design System & Aesthetics**:
   - Keep every color, radius, shadow and font in a single token file (CSS variables) and consume tokens everywhere; never hardcode hex values in components.
   - Prefer crisp 1px borders and one subtle shadow scale over blurry default shadows. Pair one sans-serif for body/headings with one monospace for tags, badges, metrics, and code.
5. **Data Layer & Reliability**:
   - Write declarative schema definitions with foreign keys, composite indexes on queried filters, and automated timestamp triggers.
   - Use connection pooling and prepared statements for serverless database execution.
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## 5. STEP-BY-STEP SCAFFOLDING ROADMAP
- **Phase 1: Workspace & Root Config**: Initialize package manager, monorepo configuration (`turbo.json`, `tsconfig.base.json`, `package.json`).
- **Phase 2: Database Schema & Client**: Set up the data layer: client, connection pool, models, and migration scripts.
- **Phase 3: Design Tokens & UI Primitives**: Build accessible `Button`, `Input`, `Card`, `Badge`, and layout wrappers inside `packages/ui`.
- **Phase 4: Core Application Routes & Handlers**: Implement primary authentication, user session handling, and application routes.
- **Phase 5: Quality Assurance & Build Verification**: Run `tsc --noEmit`, ESLint, Prettier, and smoke test suites to ensure zero compilation or runtime errors.
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## 6. EXECUTION INSTRUCTIONS
1. Review all specifications, architectural guardrails, and stack choices above.
2. Present the full monorepo directory tree structure.
3. Systematically generate the complete, production-ready codebase according to the 5-phase roadmap above — starting with the root workspace setup, followed by the database schema, UI design system package, and full-stack application routes until the repository is fully scaffolded and ready to run.