Ask HN: Setting terms for buying back

Looking for some business advice HN.

Say you have an idea and some capital and need partners for sharing risk. But you want to set a clause for being able to buy the property back.

What could be a possible set of terms to do so? Both while the firm is private and potentially public (in which case only the private part will be bought by me).

The intention is not to swindle anyone and lets assume all 3 of us understand the market currently.