How to automate image stacks based on filename?

Hi, i'm trying to create a script to sandwich pairs of images together to create new images.

Basically, I have a series of images titled like this:

test_1

test_1_add

test_2

test_2_add

test_3

test_3_add

I want photoshop to take "test_1_add", place it as a layer (with blending mode as add) on top of "test_1", and then save as a new file. Then I want it to repeat this process with "test_2", "test_3", etc. In a perfect world, this would all be automated, so that after setting up the script, all it would take is one click and then everything would be processed.

Is this doable? Please let me know where to start with making this happen. Thanks!