They already do, or at least Claude Code does. It will search for a method name, then only load a chunk of that file to get the method signature, for example.

It will use the general information you give it to make educated guesses of where things are. If it knows the code is Vue based and it has to do something with "users", it might seach for "src/*/User.vue.

This is also the reason why the quality of your code makes such a large difference. The more consistent the naming of files and classes, the better the AI is at finding them.