Here's an example where I have to type way more than I expect.

All choices are very bad; I have to type "constr" to match "constraints", when I should only need to type "c" to get it as the first hit.

In short, the autocompletion should emphasize near things (local variables/arguments, nearby functions, and so on), over farther-away things (like imports and snippets). I think character distance is as important a clue as lexical-scope distance.

I've also noticed that the autocompletion is peculiarly picky about case. Notice how "Constraint" (capitalized) is not among any of the hits. It's nice that case is used as a hint, but I really expect "Constraint" to be the second suggestion.