feat: Initial CBPOA commit — 武汉儿童呼吸疾病风险评估系统

Context: Build a spatial risk assessment system correlating air quality
data with children's respiratory disease incidence across Wuhan.

Approach: FastAPI backend serving PostGIS spatial queries, React
frontend with Deck.gl maps, and a PyTorch SpatialTemporalGCN pipeline
for multi-day (1d/3d/7d) risk prediction.

Changes:
- backend/ — FastAPI API with auth (JWT), alerts, risk analysis,
  geocoded case data, grid statistics, and report endpoints
- frontend/ — React dashboard with interactive risk maps, alert
  monitoring, district comparison charts, and timeline player
- models/ — SpatialTemporalGCN model with trained weights and ONNX
  export for inference
- scripts/ — ETL pipeline for weather + medical data, grid generation,
  feature engineering, training, and daily inference
- deploy/ — Docker Compose configs for backend, frontend, and MLflow
- docs/ — API docs, deployment guide, user guide, and code review

Impact: Enables spatial risk visualization, alert monitoring, and
ML-driven health risk forecasting for environmental health teams.

backend/auth/dependencies.py

@@ -0,0 +1,27 @@
+"""FastAPI dependencies for authentication."""
+from fastapi import Depends, HTTPException, status
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
+
+from .service import decode_access_token
+
+security = HTTPBearer()
+
+
+async def get_current_user(
+    credentials: HTTPAuthorizationCredentials = Depends(security),
+) -> str:
+    """Extract and validate the current user from the Authorization header."""
+    payload = decode_access_token(credentials.credentials)
+    if payload is None:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Invalid or expired token",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    username: str | None = payload.get("sub")
+    if not username:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Token missing subject",
+        )
+    return username

backend/auth/middleware.py

@@ -0,0 +1,3 @@
+"""Auth middleware — currently a no-op placeholder for future rate-limiting / audit logging."""
+# Middleware for auth events can be added here (e.g., failed-login rate limiter).
+# Kept as a placeholder so the module structure is complete.

backend/auth/models.py

@@ -0,0 +1,21 @@
+"""Pydantic models for authentication."""
+from pydantic import BaseModel, Field
+
+
+class UserCreate(BaseModel):
+    username: str = Field(..., min_length=3, max_length=50)
+    password: str = Field(..., min_length=6, max_length=128)
+
+
+class UserLogin(BaseModel):
+    username: str
+    password: str
+
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str = "bearer"
+
+
+class UserOut(BaseModel):
+    username: str

backend/auth/router.py

@@ -0,0 +1,34 @@
+"""Authentication endpoints: login, register, whoami."""
+from fastapi import APIRouter, Depends, HTTPException, status
+
+from .models import UserCreate, UserLogin, Token, UserOut
+from .service import authenticate_user, create_access_token, create_user
+from .dependencies import get_current_user
+
+router = APIRouter(prefix="/api/auth", tags=["auth"])
+
+
+@router.post("/login", response_model=Token)
+async def login(body: UserLogin):
+    if not authenticate_user(body.username, body.password):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect username or password",
+        )
+    token = create_access_token({"sub": body.username})
+    return Token(access_token=token)
+
+
+@router.post("/register", response_model=UserOut, status_code=status.HTTP_201_CREATED)
+async def register(body: UserCreate):
+    if not create_user(body.username, body.password):
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail="Username already exists",
+        )
+    return UserOut(username=body.username)
+
+
+@router.get("/me", response_model=UserOut)
+async def me(username: str = Depends(get_current_user)):
+    return UserOut(username=username)

backend/auth/service.py

@@ -0,0 +1,66 @@
+"""JWT token creation and password hashing utilities."""
+import os
+import logging
+from datetime import datetime, timedelta, timezone
+
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+
+logger = logging.getLogger("cbpoa.auth")
+
+SECRET_KEY = os.getenv("AUTH_SECRET_KEY", "cbpoa-dev-secret-change-in-production")
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_MINUTES = int(os.getenv("AUTH_TOKEN_EXPIRE_MINUTES", "480"))
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+# In-memory user store (replace with DB table when auth matures)
+_users: dict[str, str] = {}
+
+
+def seed_default_admin() -> None:
+    """Create default admin user if no users exist."""
+    if not _users:
+        default_user = os.getenv("AUTH_DEFAULT_USER", "admin")
+        default_pass = os.getenv("AUTH_DEFAULT_PASSWORD", "admin123")
+        _users[default_user] = pwd_context.hash(default_pass)
+        logger.info("Seeded default user '%s'", default_user)
+
+
+def verify_password(plain: str, hashed: str) -> bool:
+    return pwd_context.verify(plain, hashed)
+
+
+def hash_password(password: str) -> str:
+    return pwd_context.hash(password)
+
+
+def authenticate_user(username: str, password: str) -> bool:
+    hashed = _users.get(username)
+    if not hashed:
+        return False
+    return verify_password(password, hashed)
+
+
+def create_user(username: str, password: str) -> bool:
+    """Register a new user. Returns False if username already exists."""
+    if username in _users:
+        return False
+    _users[username] = hash_password(password)
+    logger.info("Registered new user '%s'", username)
+    return True
+
+
+def create_access_token(data: dict) -> str:
+    to_encode = data.copy()
+    expire = datetime.now(timezone.utc) + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    to_encode.update({"exp": expire})
+    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
+
+
+def decode_access_token(token: str) -> dict | None:
+    try:
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        return payload
+    except JWTError:
+        return None