[lstodd]

I wonder if you'd have to recertify after each pr merge

[toast0]

You would need to certify each signed release. Most likely, you wouldn't make a signed release for each PR, because of the time and expense involved, until you got to the point were changed were few and far between.

[amenod]

No, just before actually releasing it. Nobody cares about the code as long as it is not running on the devices.