Keep six to twelve months of expenses, more than the usual three to six, in a savings account and a liquid fund kept apart from company runway.

Founder income is lumpy and your main asset is illiquid, so the bigger buffer is what lets you say no to a bad deal. Build it with a fixed transfer on the day your salary lands, add every bonus or payout, and keep it in an account you use for nothing else. Decide before a crisis whether you will ever spend it on the company.