If the process involves haggling and negotiating then it is a game between founders rather than a business decision. Sure it was someone's idea and someone wrote the code and someone picked up the pizza and made the coffee and you could dig through the past and assign values to all those things. It's totally fucking stupid but you could still do it.
What matters is not how you got here but where you will go. What matters is not how much work you have done but what work each of you is going to do. If you pivot are you going to claw back equity from the idea guy? When the code base is rewritten in Go to support that pivot is the programming guy losing stock?
Allocate equity based on pots of coffee made [one of you will like this idea] or divide it equally and focus on trying to make so much money that an additional 5% equity split doesn't matter.
Good luck.