Why is baking soda included in sourdough cracker recipe? I'm following a recipe for crackers made with unfed sourdough starter (other ingredients are flour, oil, and salt). It also calls for 1/4 tsp baking soda and I'm wondering why since the dough sits on the counter several hours before baking, and can also be stored in the fridge for days. I would think the baking soda would no longer be active to work as a raising agent. Is it possible it is there for some other reason?

Am I correct that the baking soda is no longer active in the dough after so many hours before baking? If so, how can it work as a leavening agent?

I've added a photo of a cracker from the batch with baking soda. Not sure if the photo shows it well, but there's a big raised bubble in the middle, although hard to say if it's due to the baking soda or the sourdough starter. I'd say 80% of the crackers have a bubble of some sort. I read somewhere that baking soda might be used to make a more tender cracker and this batch is in fact not crispy (big disappointment). My next batch will be identical but without baking soda, so I'll see!
In addition to leavening, baking soda increases the PH of the dough. Since your recipe uses sourdough starter, it may be fairly acidic. Adding baking soda will make the dough less acidic. The PH level, in turn, is important for browning: a high PH level facilitates the Maillard reaction, giving you brown and toasty crackers.