If you pick the wrong one and fight a stealth scout instead of a stealth death fleet, well, you picked the wrong one. But you will be basing this decision on the value of the property you are defending. I don't care if the enemy brings a giant death fleet to destroy one of my scouts on some valueless asteroid, but I would care if the enemy brings anything to attack my homeworld. I can always look at the combat reports and see that my scout was vaporized by a battlecruiser coming out of stealth afterwards.
As far as stealth and the tactical map, you are saying that range has zero effect on stealth detection? Just want to make that clear.since such a ship is undetectable at any distance on the tactical map, unless its stealth actually decreases, due to firing weapons, exiting an asteroid belt, etc.
How about this for a situation: The person you are playing with is going for the meta-game strategy of "I'm going to annoy you into submission by engaging you one scout at a time, in essence, I'm going to use douchebag tactics to waste as much of your life as possible." If you don't think this isn't a common reality, then you probably don't play many online games. I state this strictly from the perspective of a player, not a designer. I've spent many an hour corpse camping people too weak to fight back against me just to ruin their day and waste their time. If possible, I'd like to see rules which prevent meta-game tactics of this type.Both these situations are reliant on the cloaked enemy acting against his best tactical interests. Worrying that these situations will actually end up being significantly annoying game-slowing factors is ludicrous.
The "arbitrary special rule" is just a basic, from-the-start assumption that once a unit has engaged you, you are able to lock onto it and determine it's presence in-system, even if it goes back into stealth. Whether or not you can see it and target it aside, you *know* that it is in-system, until it is destroyed or flees. As far as only wanting to engage with half your fleet: if you don't like the music, don't come to the party. Like you said, it's not in a players best tactical interest to engage with less than his full force anyways. If it's in-system, it's a fleet asset that is involved in the combat, whether you want it to be or not. I'd prefer if you could get a count of the number of ships stealthed in a system.Adding a special-case rule for when an empire is made aware of the presence of an enemy unit isn't simpler at all, and adds a lot of annoying restrictions. For example, what if I have 10 stealth units in the system, but I only want to attack with five of them? It's impossible, because all units in the system are present on the tactical map, and in the system you propose, combat will not end until all of the cloaked ships are destroyed, or a cease-fire is ordered, which means that the surprised player must know how many enemy ships are present. In the system I propose, the player is free to attack using whatever ships he wants, without having to give any special commands or being limited by seemingly arbitrary special rules.
I know this is just making you scream, but otherwise stealth (at a level which is undetectable by your enemy) becomes the massively-all-powerful tool that everyone is going to go for. Aside from being completely untargetable, untrackable on the galaxy map, and invisible on the tactical map, the benefits of stealth allow you to drift in and out of combat at will and pile up forces literally anywhere you want them. This encourages players to do whatever is cheaper; either research max stealth technology and become godlike destroyers of all in their path, or research max detector technology so that stealth is useless against them. There isn't a whole lot of give-and-take or strategy involved here. If your stealth is higher than your enemy's capability to detect, you pretty much win, because he can't effectively fight back against you, concentrate forces against you, or defend against you.
My concern is that when a unit "stops firing", and goes back into an undetectable state, it may still be on your list of threats, but you have no idea if it has fled, or if it's still lurking about waiting for reinforcements. I want to be able to know one way or the other whether it is in-system or not. There has to be some kind of balance to the seemingly overwhelming power of undetected stealth.