BeerBorg

Does candi syrup have to be boiled before adding to fermentor?

No you don't have to and many don't but based on what I've kept bookmarked, one company suggests the following:
CSI’s Candi Syrup is filled and packaged under sterile conditions.
If adding candi syrups to primary or secondary the following steps are recommended:
1.Sanitize the exterior of the packaging.
2.Mix a volume ratio of 2 parts candi syrup to 1 part water.
3.Boil on low heat for 15 minutes
4.Let coolto room temperature covered
5.Add to fermenter and gently stir

So based on the above, No. But based on fear it is recommended.

I've used candi syrup once, adding it directly to the fermenter when krausen fell.

You can add it for the full boil, you can add it in the last 10 minutes of the boil, or you can feed it during fermentation. I will do any of these things, but if using a lot of sugar in a high gravity beer, I always feed it, in anywhere from 1-3 feedings depending on how much I'm using (IE 2# of it in a beer that was 1.07+ to start with, I will feed it in 3 batches). With some yeasts, like 3787 or WLP530, you can actually get better attenuation by feeding it like this. Feed each time the krausen starts to fall, about 3 days from pitch and about 3 days apart after that (it will re-krausen every time you feed it, and 3787/WLP530 will tend to blow off when you do it).

mine was supposed to go in at 5 minutes and I forgot it
I know, STUPID
So I added after I poured onto yeastcake (another first for me)