I don't think you read every details of all the documentation and you
want quick answer ...
> https://www.debian.org/doc/
I don't think I should be reading every detail of all the documentation to get the answer to the simple quesiton I posed. My argument is precisely that this is such an important question that one should be able to find it without spending days digging through all the Debian documentation.
You need to learn how to get information by yourself
You need to learn to be less arrogant.
Check google with keywords like
"debian testing library transition"
"debian security update policy"
I had checked google aplenty before you suggested it. I would expect an answer to my question by Googling something like "Debian ABI change policy". I did Google this phrase, and every possible phrase I could think of, and couldn't find a clear answer.
The first phrase you suggested gives as the first result this page:
This page indeed suggests that an ABI change requires submitting a package to the Debian experimental repository, which implies the change wouldn't make it into a Debian minor version bump or a security update. However, this page seems to be aimed at developers and not users. I would argue that my question applies to users too (users like me, for example). Moreover, one could hardly argue that "library transition" is a phrase that would immediately come to the mind of a user who is interested in "ABI changes".
The second phrase you suggested does not show any results on the first page that are related to ABI changes (at least here on my end).
Anyway, I hope someone else will contribute to this conversation, because it doesn't look like you are hearing what I'm saying.
Best regards,
Jakob