What never goes in

The point of a workspace is that you stop deciding what to attach, because the folder is already the answer. That convenience is exactly the risk. Six months in you will drag something into it on autopilot that carries a duty you did not think about at the moment of dragging. So the limit gets written down once, at the top, while you are still thinking clearly, and it is written as categories rather than instances, because you cannot enumerate what has not arrived yet. This is separate from key and password hygiene, which is its own habit. This is about the material you are trusted with.