any .Deb distributed by apt needs to be signed by a gpg key and that key needs to be from a trusted source.
when code changes are sent to the LinuxCNC repositories in git hub, a series of run time tests are triggered. If the tests all pass, the buildbot is triggered and fesh debs are built automatically for a number of distributions and then become available in our apt repository. To access these you also need the gpt key. The original LinuxCNC buildbot could no longer do its thing from about Debian 10 due to changes in the Linux/Debian way so it stopped and could never be jumpstarted to life for neweer distros....
A new buildbot in training was created but to this day it has never grown up into the official LinuxCNC buildbot but you can find it here.
buildbot2.highlab.com
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This workflow is different to the Debian way. To get into Debian, you need to upload the source to Debian's buildbots manually into unstable (sid) branch. As long as it works well, it is pushed to Debian testing and when a new Debian release is made, testing is promoted to stable (currently Trixie). Trixie is basically locked for the duration of the Debian version but there may be an opportunity to push bug fixes (eg 2.9.7) to a point release of Debian Trixie. pheww!
