kin: BATON-008-backend_dev

backend/db.py

@@ -341,9 +341,10 @@ async def get_registration(reg_id: int) -> Optional[dict]:
 
 
 async def update_registration_status(reg_id: int, status: str) -> bool:
+    """Update registration status only if currently 'pending'. Returns False if already processed."""
     async with _get_conn() as conn:
         async with conn.execute(
-            "UPDATE registrations SET status = ? WHERE id = ?",
+            "UPDATE registrations SET status = ? WHERE id = ? AND status = 'pending'",
             (status, reg_id),
         ) as cur:
             changed = cur.rowcount > 0