"Solving Jepsen" is kind of a misleading way to say "debugging issues found by Jepsen". The former made me expect some kind of general solution to distributed consistency.

> And ultimately, adding quality tests is the best you can do to improve your software.

Tests are great, but that's not "the best you can do". You can redesign things to be simpler, and there's even an example of that earlier in the article:

> By re-architecting the design, the code could be hugely simplified. So, I had rewritten the whole thing from scratch over the past few months.

> The rewritten, simplified codebase did fix a variety of Jepsen issues. The last major stronghold was the bank test.

A better design can make it easier to informally "prove" the absence of certain issues.