Ask HN: How to handle ownership when doing side projects with collaborators?

for example, doing a software side project with a collaborator, where the main purpose is for fun, but you know there’s a tiny chance it could turn into a business.

when it’s too early and informal to incorporate or do any official equity splits, because who knows what the future will be like (and the intention is just a fun side project)

but where you also want a reasonable thing laid out in advance so that if it takes off, people aren’t surprised

and then for ip - is it that everyone owns everything? everyone owns nothing? (and what about non-shareable ip, eg brands and urls)

and then there’s the harder variant where it’s a money making side project, but where you expect it to make a tiny amount, so you want to define a split, but you also don’t want that split to be the answer if it blows up and becomes a bigger thing (because maybe only one person works on it long term)

the ideal would be a good default answer that most people would find reasonable, accounts for changing roles over time, and isn’t complex. like how for starting a company, 50-50 or 49-51 with a 4-6 year vest is a common default that is simple, accounts for involvement over time. something like that perhaps, though a 4-6 year vest doesn’t feel appropriate for a part time side project!

there’s of course the answer of don’t define it up front, but then if it goes big then both parties are likely to wish they had a basic structure up front