This bugfix derives from a thread created elsewhere and noted on the beamdog forum by @caruga:
When you send a thief to disarm a trap, usually they walk up to the edge of it and it vanishes with a special sound. In some rare instances when the thief is sent, they don't stop at the edge of the trap but proceed right into it, springing it on themselves. This is different than having merely failed to disarm the trap and sprung it instead. They don't even manage to attempt the disarm, but actually proceed right into the trap itself.
It's not clear if this has more to do with the traps themselves- particularly given that they're all larger-sized traps- or whether it's something more general, but for sure it happens in these instance more than others:
1. Durlag's 2nd level wall smash trap (AR0512- x=2603, y=890)
2. Firewine Ruins Fireball trap (AR5201- x=572, y=1471)
3. Nashkel Mines Entrance to Level 3 (AR5403- x=3180, y=2558)
Erm, actually I just tested them to find that, in fact, they're already working better (but not correctly) in BGEE than vBG1...
1. It seems like the only way to disarm it that works is by standing at around x=2535, y=864 before clicking the disarm. You still walk right into it, but the disarm comes fast enough not to trigger the trap springing. Unfortunately if you approach the trap from most anywhere else, even wearing BOOT01, you disarm the trap a split second before it smashes you.
2. For this one, it seemed possible with BOOT01 to walk straight into the center without tripping it, but the disarm should occur at the edge. Sure enough doing the straight-forward disarm shown below without BOOT01
set off the trap. Also approaching from a different angle makes the distance walked through the trap itself longer. You can see in the screenshot that the thief must walk about 1/3 of the trap width before they disarm it.
3. This one usually works perfectly fine even with BOOT01 off in vBG1, stopping the thief right in front of the trap successfully... if you approach the outer ring trap from the center. However, if you approach from a different angle- perhaps having tried to circumnavigate it first, you end up springing the trap instead, and this time you walk clear through it up to the next trap for the disarm point.
I'll list more here if I find them.
If all traps have a specific location designated for disarming them, then it looks like we need to find every problem trap and list it. If all traps have a common pathfinding algorithm, however, it needs to be tweaked.
This is a post from someone named th3rulXT on the sister thread for this issue on the Friends of Baldur's Gate subreddit forum in case it has merit here:
'i would suggest to had a minimal distance from the trap so that a thief that is X pixel from the trap center (where X could be "trapwidth/height + a constant") . Usually one of the best way to do the trick unless something like; "If PJ "walksOnTrap" then if PJ "disarmingState" then DoNothing else "TrapLaunch(PJ)"" is possible'