Weapon-like Spell + Sneak Attack : Saving Throw

[ManInOrange]

If a character makes a sneak attack with Inflict ____ Wounds, if the target succeeds on the Fortitude save, are there any written rules for whether the sneak attack damage can still apply, if it is halved, or if it is inflicted in full?

If there is nothing written, what would you suggest makes the most sense?

[Curmudgeon]

Yes, there are rules for combining weaponlike spells with sneak attack in Complete Arcane on page 86. If the spell qualifies (that is, has a successful attack roll and deals damage) then the sneak attack damage is added and is of the same type as the spell deals. Here is the basic rule for spell saving throws (from Player's Handbook on pages 176-177):
The Saving Throw entry in a spell description defines which type of saving throw the spell allows and describes how saving throws against the spell work. It's a saving throw against the spell to halve the spell's damage, so that's exactly what it does; it doesn't halve the sneak attack damage because there's no saving throw for sneak attack.