"Offline" heart rate data

Is there a way to save this "Offline" HRM data and collect it, when banglejs and phone connect? Is this planned?

Not sure if you search specifically for a gadgetbridge HRM "cache" or any offline HRM while doing sports. Some thoughts on this (not knowing what you know already):

• There are a number of apps recording hrm offline like recorder or run app. But need to be started/stopped manually and later downloaded manually. I am not aware of an automatic sync. Typically you set them to sample hrm much more often than you might have set for the health app.
  
• For soprts the build in sensor is not very reliable with the current firmware. But Bangle can recieve chest belt signal and store this (or both) also offline
  [see https://forum.espruino.com/conversations/372681/ for more information about PPG at rest / strong movement]