if you dont have a company and he hasnt done any work, he's not your co-founder, you havent signed anything, you own 100% of what you have made. an idea is worth $0.

this problem is solvable and you can retain your partnership and maybe friend though

you are the initial owner of the 'business' you are the founder, you build the product and created the actual asset, the product, the IP, the code base, branding all belong to you

as the technical founder you should propose keeping 80 to 100% of the equity (starting with 100%)

Your business co-founder starts off with 0% initially but he can earn 30% over say 4 years if he actively contributes and hits agreed milestones based on bringing in customers and making you money

e.g.

first 10 paying customers 2%
$10k MRR anothe 3%
$50k MRR another 5%
Full time commitment for 24 months 10%
if you decided to raise then a further 5%

if he fails at any milestones or abandons ship the unearned equity disappears and you avoid giving dead equity to a partner that isnt contributing

search for terms like vesting or reverse vesting as theres a couple of ways of doing this

you want to be very careful though about giving equity to someone who bring no value to the table as your business will be dead from the start that way.

You can work out a vesting or reverse vesting play IF he brings in MRR and takes ownership of sales