@kartik, This field has to be updated by the script/person(in case of manual entry) actually making the Employee Checkin Records. It is not possible to reliably determine if all the data has been synched from a biometric device to ERPNext from within ERPNext, especially in multi-device scenario (At least not without assuming stuff).
Hence, you wouldn’t find any reference to code updating this field in ERPNext code base.
How are you currently updating the Employee Checkin records?
In case you are using this script, it now updates this field for you after the sync is complete. All you have to do is setup the
'shift_type_device_mapping' in the config.
On second thought, it should be possible to update this field from within ERPNext by assuming only minimal stuff, if ‘shift-device-mapping’ is provided… … we can probably add this function to ERPNext with minimal changes and get this working… But, adding this feature within ERPNext comes with a few minor drawbacks which should be a non-issue for most scenarios.