> But often the packages also talk through simple accesses of values like `X.someproperty`. I've seen situations where maintainers would add and remove these properties and break their own other libraries. Better "enforcement" of these types of things - however that would look like - would be a huge improvement for the time sink that is maintaining a Julia package.

I think this is a cultural issue to a large degree. I think even if there were better enforcement, it's just a question of coding of discipline to then actually not break something. If it were easier to anticipate what sort of breakage a change could entail (say, by making clear & documented _by the core language_ what is considered a breaking change, and then actually not even doing "technically breaking" changes and using deprecations instead), this COULD change.

That being said, that requires a very different development workflow than what is currently practiced in the main repos of the language, so there's quite a bit of an uphill battle to be had (though such issues happen there all the time, so solving that would actually help here the most, ironically).