Fix session cookie size issue by implementing server-side sessions with Flask-Session

app.py

@@ -16,12 +16,19 @@ from functools import wraps
 import secrets
 import base64
 import hashlib
+from flask_session import Session
 
 app = Flask(__name__)
 app.config['UPLOAD_FOLDER'] = tempfile.mkdtemp()
 app.config['SECRET_KEY'] = os.getenv('SECRET_KEY', 'secret')
 app.config['MAX_CONTENT_LENGTH'] = 1000 * 1024 * 1024 * 1024  # 1000TB
 
+# Configure server-side sessions to avoid cookie size limits
+app.config['SESSION_TYPE'] = 'filesystem'
+app.config['SESSION_FILE_DIR'] = '/tmp/flask_sessions'
+app.config['SESSION_PERMANENT'] = False
+Session(app)
+
 # Load environment variables
 load_dotenv()