> what is the best calculation to make when trading off code quality vs features?

> do most YC startups write tests and try to write cleanish code in V1 or does none of this matter?

It only matters when bad code hurts your overall business velocity - what that means, only you can answer.

Nobody's writing tests for their purist aethestics, they're there to let you go faster - but there's an up-front cost you have to pay for them. Sometimes that's worth paying, sometimes the land grab is more important.

There's no single answer to this question.