This is intentionally a technical post, soliciting feedback on the technical approach. :-)

The changes Stas are talking about are mostly refactoring which will not, in and of itself, affect anything user-facing. That said, Stas is working on this primarily to lay the groundwork towards resolving T121430, which would enable a greater rollout of the completion suggester; you can see that that task blocks T121616, which is the task which tracks things we need to do to roll the completion suggester out more broadly.

Hopefully that provides some context. :-)

Thanks,
Dan