Make container traps deterministic (either as a hash of their object ID, or stored as a field on the object) rather than computing the trap when it’s triggered based on Luck. Untrapping them successfully can then yield an item related to the trap, which then gets deposited inside the container. The items for each type of trap are:

• Hallucination gas = potion of hallucination
• Paralysis = potion of paralysis
• Electric shock = 0:1 wand of lightning
• Tower of flame = potion of oil
• Poisoned needle = nothing
• Poison gas = potion of sickness
• Explosion = land mine