Can a trap be disabled without a detection roll

[Castrin]

Had an interesting rules question that I think I know the answer to but I wanted others opinions/rulings.

Situation. character ran into a reoccurring trap without detecting is and set it off. After suffering the effects the player said that they should now be able to deactivate it. However I said that they would still need to make a Perception check to be able to do that regardless of if it had been set off. I refer to this entry:

Source Starfinder Core Rulebook pg. 410
A character must first detect a trap in order to attempt to disable it, since only through observing particular details about the trap can the character know the proper countermeasures. Even if a trap has already been triggered, characters can still attempt to deactivate the trap. Some traps no longer pose a danger once they’ve been triggered, but the PCs might be able to stop the trap’s ongoing effects, if any. Other traps might not have ongoing effects, but reset over a period of time; characters can still attempt to disable the trap during this time.

I find that allowing people to just run through traps to "detect" them doesn't mean they know how the trap works so why should they know how to deactivate it? I think I'm doing it right but I'd welcome other's take on this.

Thanks

[John Mangrum]

I would say you can certainly "observe particular details about the trap" by witnessing it going off on you.

[Metaphysician]

Yeah, I would say that under ordinary circumstances, a trap going off is like a character making an attack: they are now exposed and observed. A PC doesn't need to make a detection roll, because they've already "passed" it.

I suppose you could have a trap whose operation is particularly cryptic, such that it can fire off without automatically revealing its nature. However, that would definitely be worth an extra rank or two of CR, just like if a given NPC were persistently invisible.

[John Mangrum]

After my previous reply I thought of a counterexample: a simple "silent alarm" trap, such as one that pings security over comms when a door is opened. I wouldn't assume PCs have "observed" a triggered trap that doesn't noticeably affect them.

[Metaphysician]

John Mangrum wrote:

After my previous reply I thought of a counterexample: a simple "silent alarm" trap, such as one that pings security over comms when a door is opened. I wouldn't assume PCs have "observed" a triggered trap that doesn't noticeably affect them.

This is true, but. . . hmm. My inclination is to say that this type of thing probably shouldn't even use the trap rules in the first place. Its "just" the special effect for a particular skill challenge, not fundamentally different than "spotting and avoiding a concealed guard".

[John Mangrum]

Still, let's say it's an invisible light beam built into a door. Open the door, and it calls for guards.

1. it's a physical device that could be noticed. If I were an operative with the "automatically get a chance to detect traps" ability I'd want the silent alarm to trigger my ability.

2. It has a negative, if delayed, effect if triggered.

3. It's theoretically possible to bypass and/or disable the trap.

These are all details that trap mechanics handle well.