WIP checkpoint: Scaffold FastAPI backend project structure

backend/app/config.py

@@ -0,0 +1,32 @@
+from pydantic_settings import BaseSettings
+from functools import lru_cache
+
+
+class Settings(BaseSettings):
+    # Database
+    DATABASE_URL: str = "postgresql+asyncpg://agp_user:agp_password@localhost:5432/agp_db"
+
+    # Redis
+    REDIS_URL: str = "redis://localhost:6379/0"
+
+    # JWT
+    SECRET_KEY: str = "change-me-to-a-secure-random-string"
+    ALGORITHM: str = "HS256"
+    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
+
+    # App
+    DEBUG: bool = True
+    CORS_ORIGINS: str = "http://localhost:8080,http://localhost:3000"
+
+    @property
+    def cors_origins_list(self) -> list[str]:
+        return [origin.strip() for origin in self.CORS_ORIGINS.split(",")]
+
+    class Config:
+        env_file = ".env"
+        case_sensitive = True
+
+
+@lru_cache()
+def get_settings() -> Settings:
+    return Settings()

backend/app/database.py

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+"""Async database engine and session factory."""
+
+from sqlalchemy.ext.asyncio import (
+    AsyncSession,
+    async_sessionmaker,
+    create_async_engine,
+)
+from sqlalchemy.orm import DeclarativeBase
+
+from app.config import settings
+
+engine = create_async_engine(
+    settings.database_url,
+    echo=settings.DEBUG,
+    pool_size=10,
+    max_overflow=20,
+)
+
+async_session_factory = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+async def get_db() -> AsyncSession:
+    """Dependency that yields an async database session."""
+    async with async_session_factory() as session:
+        try:
+            yield session
+            await session.commit()
+        except Exception:
+            await session.rollback()
+            raise

backend/app/main.py

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+"""FastAPI application entry point."""
+
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+
+from app.config import settings
+from app.routers import auth, users, worlds, assets
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Application lifespan: startup and shutdown events."""
+    # Startup: initialize database, connect to Redis, etc.
+    yield
+    # Shutdown: close connections, cleanup
+
+
+app = FastAPI(
+    title=settings.app_name,
+    version=settings.app_version,
+    description="Agentic Game Platform - Backend API",
+    lifespan=lifespan,
+)
+
+# Include routers
+app.include_router(auth.router, prefix="/api/auth", tags=["auth"])
+app.include_router(users.router, prefix="/api/users", tags=["users"])
+app.include_router(worlds.router, prefix="/api/worlds", tags=["worlds"])
+app.include_router(assets.router, prefix="/api/assets", tags=["assets"])
+
+
+@app.get("/api/health")
+async def health_check():
+    """Simple health check endpoint."""
+    return {"status": "ok", "app": settings.app_name}