>"We just want to search your house for 30 minutes" or "you can have your document back after we photocopy it, so no warrant needed."
This scenario would be quite a bit more akin to "let me have that locked briefcase you're carrying through security, no need for you to unlock it" and then returning it to you locked after 10 minutes.
Was that a 4th amendment search if they claim that they didn't look through your briefcase?