I think this sounds good. Maybe 1%. In all likelyhood, this company will not have any measureable value without significant outside contribution. At a certain p

I think this sounds good. Maybe 1%. In all likelyhood, this company will not have any measureable value without significant outside contribution. At a certain point, even if it were possible to win enough equity from the cofounder, that would likely make it impossible for the company to parcel out equity in the future. A product with few customers and a largely allocated cap table, would likely assure no one would work on this in the future. Try and leave on amiable terms, and ask for a percentage or a flat rate warrant. If the company pays back the original investor and makes a profit, your time will be valued at /some rate/ and you will be paid that back. The most important thing is try and leave on decent terms.