I'm about half way through my second playthrough of the game now, and realised that on the first mission at Milwaukee Junction a turret did see me. My minimap went to "hostile", but the turret did not fire, and (as far as I can tell) no alarm sounded. Being seen by any turret appears to immediately turn the minimap to saying "hostile" -- there is no 'alarmed' phase for turrets, it appears.
Does this disqualify me from Foxiest of the Hounds?