Cursor em Profundidade — Composer 2, Agentes e Cloud

@specs/billing.md @src/models/user.ts @src/db/schema.ts

Implement the billing module from @specs/billing.md.

Requirements:
- Follow the existing model patterns in @src/models/user.ts
- Use the schema from @src/db/schema.ts
- Write Vitest tests for each endpoint BEFORE implementing
- After implementing, run: pnpm lint:fix && pnpm vitest run
- If any test fails, fix until all pass

Create a plan first, then execute one task at a time.

@file specs/auth.md @file src/api/users.ts @git diff

Review the changes in @git diff against the spec in @file specs/auth.md.
Does the implementation match the spec? List any deviations.

# Cursor Rules

## Stack
TypeScript, Next.js 16, React 19, Tailwind CSS v4

## Conventions
- 2-space indent, single quotes
- Components in PascalCase
- Always use <Link> for internal navigation
- Always use Vitest (never Jest)

## Code Style
- Prefer functional components
- Use TypeScript strict mode
- No `any` types — use `unknown` instead
- Always handle errors explicitly

.cursor/
├── rules/
│   ├── backend.md        # Regras para Go
│   ├── frontend.md       # Regras para React
│   └── tests.md          # Regras para testes