# Project Rules

## Architecture
- Clean architecture with domain, application, and infrastructure layers
- Domain models must not import from infrastructure
- Use dependency injection for all services

## Code Style
- TypeScript strict mode, no implicit any
- Use Result<T, E> for error handling in domain layer
- Prefer composition over inheritance
- Maximum 3 parameters per function; use options objects for more

## Testing
- Unit tests for domain logic (no mocking frameworks)
- Integration tests for API endpoints
- E2E tests for critical user journeys with Playwright

## Dependencies
- Do not add new dependencies without discussing first
- Prefer standard library over third-party for simple tasks

# Kotlin Conventions

## Language Features
- Use Kotlin 2.x with coroutines for async work
- Prefer data classes for DTOs and value objects
- Use sealed classes/interfaces for domain errors
- Extension functions over utility classes

## Spring Boot
- Constructor injection (no field injection)
- Use @ConfigurationProperties over @Value
- Prefer WebFlux for reactive endpoints
- Use Spring Security with method-level security

## Testing
- JUnit 5 with Kotest assertions
- MockK for mocking (not Mockito)
- Testcontainers for integration tests
- Use @Nested for test organization