API key come hash SHA-256, una per sessione, TTL rinnovabile (#41)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/backend/api/middleware/api_key.py

@@ -1,10 +1,17 @@
 """API Key authentication dependency for FastAPI."""
+from datetime import timedelta
+
 from fastapi import Depends, HTTPException, Request, status
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from src.backend.database import get_db
+from src.backend.config import settings
+from src.backend.models.orm.api_key import ApiKey
 from src.backend.models.orm.user import User
+from src.backend.services.auth_service import hash_api_key, utcnow
+
+_RENEW_INTERVAL = timedelta(minutes=5)
 
 
 async def get_current_user(
@@ -24,15 +31,25 @@ async def get_current_user(
         )
 
     result = await db.execute(
-        select(User).where(User.api_key == api_key, User.active == True)
+        select(ApiKey, User)
+        .join(User, User.id == ApiKey.user_id)
+        .where(ApiKey.key_hash == hash_api_key(api_key), User.active == True)
     )
-    user = result.scalar_one_or_none()
+    row = result.first()
+    now = utcnow()
 
-    if user is None:
+    if row is None or row[0].expires_at <= now:
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
-            detail="Invalid or inactive API key",
+            detail="Invalid or expired API key",
         )
+    key_row, user = row
+
+    # Sliding TTL, written at most once per _RENEW_INTERVAL to spare the DB.
+    if key_row.last_used_at is None or now - key_row.last_used_at > _RENEW_INTERVAL:
+        key_row.last_used_at = now
+        key_row.expires_at = now + timedelta(hours=settings.api_key_ttl_hours)
+        await db.flush()
 
     # Store user_id in request state for access logging middleware
     request.state.user_id = user.id