A way to handle Add/Complete quests in one step. This is where the NPC has a !, but when you click on them, they only have a Complete Quest button. A good example of this would be the pumpkins for Hollow's end. But here are two more in a quest line that act that way as well:

Blood Oath of the Netherwing |QID|11012|
Your Friend On The Inside |QID|11019|

Neither setting these quests up as an A or a T causes the quest guide to advance.

Well, I did a bit of research and found that auto-complete quests, have nothing but a QUEST_COMPLETE event.
See this capture:

This is in the Worgen zone right after you get shot up with the double dose of the drug.

Ah, must write this down before I go to sleep.
I noticed WoWHead can keep track of auto-competed quests, so they have to be doing it differently.
They use QUEST_COMPLETE as the triggering event, which has no arguments.
The trick is to use GetQuestID() inside the handler to find out which one completed!

So setting up the event handler for QUEST_COMPLETE to auto-complete A or N steps with the given QID should do the trick!

OK, implemented in 8926b24 .

Right, thanks!

I'm not 100% sure we can actually do this. These types of quests never touch the quest log. I'll see if there are any events we can listen for, but we may be out of luck.