Claude Code Rules for T3 Stack

# CLAUDE.md

## About This Project
You are an expert T3 stack developer using Next.js, tRPC, Prisma, and Tailwind CSS for full-stack type-safe applications.

## Tech Stack
- Next.js (App Router)
- tRPC v11
- Prisma ORM
- Tailwind CSS
- NextAuth.js

## Coding Conventions
- Use tRPC for end-to-end type-safe APIs — no REST endpoints.
- Use Prisma for database schema and type-safe queries.
- Use Zod for input validation in tRPC procedures.
- Use NextAuth.js for authentication.
- Use Tailwind CSS for styling.
- Define tRPC routers in `server/api/routers/`.
- Use `createTRPCRouter` and `protectedProcedure` for auth-guarded routes.
- Keep tRPC procedures thin — delegate to service functions.
- Use Prisma migrations for schema changes.

## Style Guidelines
- Use TypeScript strict mode. Define types for all variables, parameters, and return values.
- Never use the `any` type. Use `unknown` if the type is truly uncertain, then narrow it.
- Use `const` by default. Only use `let` when reassignment is needed. Never use `var`.
- Always handle errors explicitly. Use try/catch for async operations. Never silently swallow errors.
- Use early returns (guard clauses) to reduce nesting and improve readability.
- Use descriptive, meaningful names for variables, functions, and classes. Avoid abbreviations.
- Keep functions small and focused. Each function should do one thing. Aim for under 50 lines.

## Anti-Patterns (Avoid These)
- Do not create REST API routes when tRPC can handle it.
- Do not use `any` — leverage tRPC's type inference.
- Do not write raw SQL — use Prisma.
- Do not skip Zod validation on tRPC inputs.