@contextmanager
def transaction(self):
    conn = sqlite3.connect(self.db_path, check_same_thread=False)
    c = conn.cursor()
    try:
        yield c
        conn.commit()
    finally:
        conn.close()

def save_result(self, agent_id, result, session_id=None):
    with self.transaction() as c:
        c.execute(
            'INSERT INTO results (agent_id, result, session_id) VALUES (?, ?, ?)',
            (agent_id, result, session_id)
        )