My spellcaster was brought down while they had a held touch spell. This means that they are now laying on the ground, out cold, with a held touch spell that should still be active. If the touch spell matters, it's basically a shocking grasp which has been modified to allow multiple touches like chill touch.
Do I discharge the spell when someone comes to touch me to heal me (provided it requires a touch)?
The rules don’t say. The accidental discharge rule is a single, throw-away line that isn’t given any support or explanation whatsoever. How, when, and why it works is left completely undefined.
It also leads to numerous (one example, another) questions and potentially serious rules exploits or failures.
More broadly, held charges are also under-defined. They aren’t quite a spell effect (for example, you don’t use up a spell’s duration while holding a charge of it), but they also aren’t quite the same as just a spell you have prepared.
Spell effects remain in place after their caster dies, unless they required that caster’s concentration. Touch spells don’t, so that doesn’t apply.
On the other hand, a caster loses all prepared spells when he or she dies. Should that apply to held charges as well? Who knows!
Basically, it’s kind of a mess, and the accidental-discharge rule in particular is just a giant rules hole. I strongly recommend ignoring it entirely.
But if you must have an answer, then I’ll just echo my answer about getting hit while holding a charge:
In general, you have to actively try to touch someone to trigger it. It requires an attack action on your part, an attack roll, and so on. In a Grapple, you have to win a Grapple check to get an attack.
A free, retributive effect like you propose is quite rare in 3.x, and usually quite weak. To be able to do it with just any touch spell is potentially overpowered and opens up shenanigans that are probably inappropriate.
According to the rules about touch spells, no, although this might be subject to GM variation. If a held spell discharged when you were touched, any attacks on you with natural weapons would discharge the spell, which they don't.
If you want an in-universe rationale, I've always imagined that the charge for the held spell is contained within one of your hands, and so avoiding any contact with the hand will avoid setting off the spell. Magi can use Spellstrike to move the charge into a weapon.
If you or your GM want to be pedantic, then technically, when you fall unconscious, you most likely touch the ground/floor (as opposed to how your feet normally touch the floor through whatever shoes you wear), and that might also discharge the spell to the floor.
