# Project Conventions

## Language
- TypeScript strict mode, no `any` types
- Prefer const over let, never use var
- Use template literals over string concatenation

## Architecture
- Feature-based folder structure under src/features/
- Each feature exports through an index.ts barrel file
- Shared utilities go in src/lib/

## Error Handling
- Use Result<T, E> pattern for expected failures
- Throw only for programmer errors
- Always log errors with structured context

## Testing
- Colocate tests next to source files (*.test.ts)
- Use factories for test data, not fixtures
- Integration tests in __tests__/ directories

# 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