# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

This is the **Paper Dynasty Web App**, a baseball simulation game migrated from a Discord bot (`../discord-app/`) to a standalone web application using **FastAPI + Model/Service Architecture**. The migration follows a service-oriented approach that prioritizes testability, maintainability, and scalability.

## Development Commands

### Environment Setup
```bash
# Start PostgreSQL database container
docker compose up -d postgres

# Activate virtual environment
source venv/bin/activate

# Install dependencies (including PostgreSQL driver)
pip install -r requirements.txt

# Copy environment configuration
cp .env.example .env
# Edit .env file if needed

# Run development server
python -m app.main
# Server runs on http://localhost:8001
```

### Testing
```bash
# Run all tests
pytest

# Run tests with coverage
pytest --cov=app

# Run specific test module
pytest tests/unit/services/test_game_service.py

# Run specific test
pytest tests/unit/services/test_game_service.py::test_create_game_success
```

### Database
```bash
# Start/stop PostgreSQL container
docker compose up -d postgres      # Start pddev-postgres container
docker compose stop postgres       # Stop container
docker compose down -v             # Stop and remove data (fresh start)

# Create database tables (once models are implemented)
python -c "from app.services.service_container import create_db_and_tables; create_db_and_tables()"

# Generate migration (once Alembic is configured)
alembic revision --autogenerate -m "Description"

# Apply migrations
alembic upgrade head

# Connect to database directly
docker compose exec postgres psql -U paper_dynasty_user -d paper_dynasty
```

## Architecture Overview

### Model/Service Architecture Pattern

This project implements a **service-oriented architecture** with clear separation of concerns:

- **Models** (`app/models/`): Pure data models using SQLModel
- **Services** (`app/services/`): Business logic layer with dependency injection
- **Controllers** (`app/routers/`): Thin FastAPI route handlers that delegate to services
- **Engine** (`app/engine/`): Stateless game simulation functions
- **Repositories** (`app/repositories/`): Optional data access layer for complex queries

### Service Layer Design

All services inherit from `BaseService` and follow these patterns:
- Constructor dependency injection via SQLModel Session
- Standardized logging with `f'{__name__}.{self.__class__.__name__}'` format
- Business logic separated from HTTP concerns
- Unit testable with mocked dependencies

### Dependency Injection

Services are injected into routes using FastAPI's `Depends()` system via `service_container.py`:
```python
from app.services.service_container import GameServiceDep

@router.post("/games/start")
async def start_game(game_service: GameServiceDep):
    # Service contains business logic, route handles HTTP concerns
```

### Migration from Discord App

When migrating code from `../discord-app/`:
1. **Extract business logic** from Discord command handlers into services
2. **Remove Discord dependencies** (discord.py, interaction objects)
3. **Create service methods** with pure business logic
4. **Add comprehensive unit tests** for service methods
5. **Create thin route handlers** that delegate to services

## Current Migration Status

**Phase 1: Service Foundation** ✅ COMPLETE
- FastAPI project structure established
- Base service classes and dependency injection configured
- Logging with rotating handlers implemented
- Virtual environment and core dependencies installed

**Phase 2: Core Game Services** 🚧 NEXT
- Extract business logic from `../discord-app/command_logic/logic_gameplay.py`
- Implement GameService, GameplayService, AIService
- Migrate core gameplay models from Discord app
- Add comprehensive service unit tests

## Key Files and Patterns

### Service Container (`app/services/service_container.py`)
- Manages database sessions and service lifecycles
- Provides dependency injection for FastAPI routes
- Configure SQLModel engine for PostgreSQL/SQLite

### Base Service (`app/services/base_service.py`)
- Abstract base class for all services
- Standardized logging and validation patterns
- Session management and error handling

### Constants (`app/config/constants.py`)
- Migrated constants from Discord app (not assumed values)
- Environment-based configuration via Settings class
- Game constants, MLB teams, rarity values from original source

### Logging Configuration (`app/config/logging_config.py`)
- Rotating file handlers per user requirements
- Console and file output with structured formatting
- Service-specific logger naming patterns

## Testing Strategy

**🚨 CRITICAL: All tests must follow test isolation guidelines to prevent data persistence issues.**

### Test Isolation Requirements (MANDATORY)

**For ALL tests that interact with the database:**

1. **Use centralized `db_session` fixture** from `conftest.py` - never create custom session fixtures
2. **Use factory classes** for all test data - never hardcode IDs or use static values
3. **Import factories** from `tests.factories` package
4. **Ensure test independence** - each test must work in isolation and repeatedly

**Example of CORRECT test pattern:**
```python
from tests.factories.team_factory import TeamFactory

def test_create_team(db_session):  # ✅ Use db_session fixture
    team = TeamFactory.create(db_session, abbrev="LAD")  # ✅ Use factory
    assert team.id is not None
```

**NEVER do this (causes data persistence issues):**
```python
@pytest.fixture
def session():  # ❌ Custom fixture
    pass

def test_create_team(session):
    team = Team(id=1, abbrev="LAD")  # ❌ Hardcoded ID
```

**📖 See detailed documentation:**
- `tests/README.md` - Complete testing guidelines
- `tests/factories/README.md` - Factory pattern documentation
- `tests/TEST_ISOLATION_GUIDE.md` - Comprehensive isolation best practices

### Unit Tests (`tests/unit/`)
- **Services**: Test business logic with mocked database sessions
- **Engine**: Test stateless game simulation functions
- **Models**: Test data validation and relationships using `db_session` + factories

### Integration Tests (`tests/integration/`)
- Service interactions with real database (isolated transactions)
- Authentication flows and session management
- Must use `db_session` fixture and factory classes

### End-to-End Tests (`tests/e2e/`)
- Complete user journeys through web interface
- Game creation and gameplay flows
- Use factory classes for any test data setup

## Development Guidelines

### Service Development
- All services extend `BaseService`
- Use dependency injection for service-to-service communication
- Log operations with `self._log_operation()` and `self._log_error()`
- Follow "Raise or Return" pattern (no optional return values)

### Documentation Maintenance
- **Update README.md files** when making substantial changes to any directory
- Each directory with significant content has a README.md explaining its purpose and patterns
- Keep documentation current with architecture decisions and new patterns
- Update relevant README when adding new services, routes, or changing patterns
- **Reference per-directory README.md files** - Future AI agents should read the README in each directory to understand its purpose, patterns, and responsibilities before making changes

### File Size Management
- **Keep all files as small as feasibly possible** for maximum maintainability
- Break large files into smaller, focused modules
- Single responsibility principle applies to files as well as classes
- Prefer multiple small service files over monolithic service classes
- Split complex models into separate files when they serve different domains

### Code Migration
- Always check `../discord-app/` for actual implementation before assuming logic
- Extract Discord command handlers into service methods
- Test service logic independently of web framework
- Keep routes thin - delegate business logic to services

### Database
- Currently configured for SQLite development
- PostgreSQL driver (`psycopg2-binary`) commented out until proper DB setup
- Use SQLModel for all data models

### Logging
- Use rotating file handlers as per user requirements
- Format: `f'{__name__}.{className or functionName}'`
- Log service operations and errors consistently