Then it sounds like slotting the regen spell into a psimetal helmet with a stress sensor would work perfectly for your purposes.
Also note that the psimetal tools and armor pieces have three sockets- so you could put the regen and resistance spell bullets into your chestplate, and switch between them using the armor controller as needed. Not as elegant as firing both of them automatically when needed, but it works if you're using your helmet slot for something else.
In any case, writing a spell to place a light source in your face (assuming you've unlocked the block conjuration tricks) is pretty simple. Selector: Caster -> Operator: Entity Position will return the position of your head in the form of a vector. The Conjure Light trick, coincidentally, takes a vector as an argument. So, Selector: Caster -> Operator: Entity Position -> Trick: Conjure Light will place a floating light source at the same location as your head whenever it fires. Slot that into a psimetal helmet with a light sensor, and every time you walk into darkness, a floating ball of light will appear right in your face.
If you want to get a little more fancy and have the spell place the light at your feet instead, you just need to subtract 1 from the Y coordinate of that position vector. You could do that by using the Extract operators to pull the x, y, and z coordinates out from the Entity Position vector, subtracting 1 from the Y coordinate, and then reassembling them into a vector using the Vector Construct operator. However, simply adding the vector (0, -1, 0) to the Entity Position vector would accomplish the same thing with a lot less space- just the vector addition operator, Vector Construct, and a single number constant (being -1, directed into the Y input on the Vector Construct operator).
... That description probably made no sense at all. I don't seem to have a working instance with Psi at the moment, so here's the result of a quick hackjob in Photoshop:
