I dislike the Tier 1 rule "All core developers are responsible to keep
these platforms, and thus ``main``, working."
In my experience, "Everyone is reponsible" means in practice "nobody
I don't think that applies here as you shouldn't even be merging a PR if it breaks CI for these platforms. And if CI isn't good enough then we should fix that.
If you still want a point of contact for those platforms then we can talk about that, but I wouldn't expect the listed folks to be as critical on those platforms to keep things functioning like they are for a tier 2 being supported by a buildbot post-merge.
Or put another way, tier 1 platforms are so critical we can't be expected to be dropped if someone isn't being responsive to questions, unlike tier 2 where we would probably drop a platform if folks weren't responsive enough.
IMO you must also put two names in front of each
platform. Otherwise, nobody will fix them when it will be broken, and
the best that we will be able to do is to just revert the change
breaking the CI which prevents adding new features just because nobody
wants to fix the CI.
Sometimes, a broken CI is unrelated to a Python change. Things break,
*all the time*, for many various reasons including vacuum cleaners
But tier 1 is the CI we run on PRs, not in the Buildbot fleet.