Hey there,
I am also wondering about this… Regarding the metadata, I suppose not. As you said they mentioned they are working on adding support for this. To my knowledge no metadata is included at all at the moment.
Regarding the structured approach: What we did at first is create separate vector stores for certain “file categories”. In our case the user selects which category they would like to inquire about in the front end. This then triggers the client.beta.assistants.update which updates the assistant to use the corresponding vector store, they same could be done at thread level. In your case you could do it automatically with another assistant or with one assistant with a forced function call before performing the file search. However, I found that this does not necessarily improve the accuracy of the file search. I also tested it with putting all files into one VS (roughly 3000 files) and it surprisingly works really well. This of course depends on your data…
Unfortunately we don’t have a lot of information about how File Search works at the moment… It would be great if the OpenAI Team would expand the documentation a bit. I posted a thread here: Assistants API File Search and Vector Stores