Ask HN: What technical stuff should a technical founder know?
Full question: What technical stuff should a technical founder know before starting a software technology company?
Being able to say no to adding more features. This is probably the most important skill. It's really easy to say yes to more and more things, and every time you do you make it less likely a user will ever see your app.
Deployment. Regardless of what you're making you need to be able to get it out there reliably.
Code quality. Spending time revisiting code to fix issues is wasted time, so writing high quality code you can understand and fix fast is key.
Testing. The easiest way to lose a user is for them to see a bug right away, so you need to be able to test well.
Security. Obviously.