I’d suggest if you’re not sure where to draw the line … maybe don’t.
It should be obvious. Founders are “there” before there is anything. Before a name. Before a product idea, usually. Before a URL, a line of code. Anything.
And they take 100.0000% of the risk. And have $0.00 in salary. And — importantly — are 100.000% committed. No matter what.
If you have an early “employee” that is 100.000% committed. Is working for $0 cash. And was there before the idea really came together, before anything.
I’d give her the title of “co-founder”. Or “Co-founding employee” or a hack in the middle. At the very least.