It’s an interesting time.
Pre-product, and certainly, pre-code … the only way you can figure out equity splits is on a relative basis. We’re 50/50 partners. We’re 2:1 partners. Etc. etc.
One you are fully established, more traditional rules tend to establish themselves. 1% for senior management. 0.2% for an experienced director. Etc. etc.
You’re somewhere between. You have a real business ($50k/mo) but … it’s a hacked MVP. You can’t scale it, you have no team around it, etc.
Your CTO, if she’s going to rebuild the entire thing herself from scratch, so it can sell … may be close to an ex-post facto founder.
Fairness is the right answer. My suggestion is in-between those two paradigms. My guess is this will net to around 5%.