In D15014#416416, @angelika wrote:

In D15014#416352, @tomek wrote:

Could you expand a little bit on your answer? Does every single project using Flow have to commit so much code into their repos?

Environments work in the same way as packages in flow-typed/npm directory. We check them in the repository as well and they're duplicated between workspaces too (for example for lodash package we have 4 files lodash_v4.x.x.js which are the same). Also react-native checks them in too: https://github.com/facebook/react-native/tree/main/flow-typed/environment. We have more of them because we have not only mobile app but also web app which uses a lot of web apis and we have multiple repos. We can reduce the amount of files by checking each workspace what exactly it needs (mobile might not need web apis) BUT I repeat: please check out https://phab.comm.dev/D15107, it de-duplicates them a lot so there are like only 10 environments added in total only in lib workspace and most of files added in this diff are deleted anyway.
I can even squash this diff and D15107 so we add only already de-duplicated environments.

I was looking for an explanation for why we need to commit the environments to our repo. It's mostly because they don't have similar locking mechanisms we have for libraries. Also, they are maintained by a community and thus can lag behind the libraries. There are some ways of avoiding committing the definitions, but there are no standard ways. We could integrate downloading them into our build pipelines, but it has some disadvantages and isn't considered a good practice.

I can even squash this diff and D15107 so we add only already de-duplicated environments.

I think it might be a good idea, if this isn't too inconvenient for you.