I know that Fate Core is a bit loose with letting you interpret the rules as they make sense in a narrative context, but I want to understand what's written regarding the use of stealth.
First, the stealth skill can be used to Create An Advantage (FC99):
You’ll mainly use Stealth to create aspects on yourself, setting yourself in an ideal position for an attack or ambush in a conflict. That way, you can be Well-Hidden when the guards pass by and take advantage of that, or Hard to Pin Down if you’re fighting in the dark.
But then in the section on active vs. passive opposition (FC131), it says in a sidebar (emphasis mine):
Sometimes you’re going to run into edge cases, where something inanimate seems like it should provide active opposition (like an automated gun) or an NPC can’t provide proactive resistance (like if they’re unaware of what the PC is doing). Follow your gut—use the type of opposition that fits the circumstances or makes the scene more interesting.
This is reiterated specifically in the section on the Attack action (FC140):
Most of the time, your target will actively oppose your attack. Passive opposition on an attack means you’ve caught your target unaware or otherwise unable to make a full effort to resist you, or the NPC isn’t important enough to bother with dice.
Does this mean that, for a stealthy character attacking another character who is unaware of their presence, they would be able to (1) use stealth to create an advantage, (putting a freely-invokable aspect on themselves), and also (2) when they attack on a subsequent turn, deny the opposition of the ability to roll dice? Under what circumstances would it make sense to give both bonuses, or to only give one or the other?