[minimaxir]

If you look at the GitHub repo, most of it is READMEs describing systems, not the models or code subleties which actually give explanations into how certain weird behaviors on Twitter happen. (e.g. the preference of certain users in the For You tab. EDIT: bad example, since there appears to be a flag for that in the code, although it does not specify which users are on the list)

[mquander]

The links in the README just go to other documents, but the repo seems to have most of the code for the components the documents are describing.

[minimaxir]

It seems to vary by service; some are more detailed than others.