What two agencies run and oversee the civil service system today?

The civil service system in the United States is primarily overseen by the Office of Personnel Management (OPM) and the Merit Systems Protection Board (MSPB). The OPM manages the federal workforce, including recruitment, hiring, and personnel policies, while the MSPB serves as an independent agency that protects the merit system by ensuring that federal employees are treated fairly and have the right to appeal adverse employment decisions.