US Patent: does sale (of the doc) constitute publishing? and preclude patenting?

If you sold it, it was your idea. That means if the buyer wants to patent it, you need to be cited as the origin. As far as I know, private discussion is not publication (which presumes widespread public dissemination). In addition, absent the public discussion/revelation anyone at all can think of this idea and patent it. Recent changes have muddied this with first to patent = the win. Many companies intentionally publish inventive details to (try to??) place them in the public domain as a troll blocking mechanism.