A potion or spell of searching: it doesn’t give you the regular searching intrinsic, but rather it detects any traps you move adjacent to with a 100% chance (regular searching isn’t guaranteed to find these, and this effect won’t find other things that searching is able to find).

Alternatively, just make it give you temporary intrinsic searching as currently implemented, but make it so that timing-out intrinsic searching (available only from this) is guaranteed to find everything.