Heat Pumps are different from gas heaters and do not require a cool down mode (firemans switch protection).
Heat Pumps require a quick disconnect from the main circuit breaker and are not required to be interfaced with the circulation pump's operation.
There is an internal pressure switch that tells the heat pump when there is sufficient flow for operation. When the pump turns off, the heat pump will cycle down too, because of the pressure switch.
Any failures of the pressure switch will allow the heat pump to turn on, but the temperature sensors on the water side, and freon side will further protect the heat pump from operation and component damage.
Basically, when it sees the freon temperatures fluctuating different from it's design, it will shut down the compressor and flash a code indicating such.
Bear in mind too that some heat pumps have the capability of activating the pump after it is off (time clock override), for the sake of maintaining the water temperature to your desired setting.
The heat pump can also allow the pump to continue to run, after the normal time clock mode (time clock extend) if the desired temperature setting has not been met by the end of the time clock cycle.
There are internal memories that are retained if you desire to connect the heat pump to be interfaced with the pump so that it turns off at the same time.