In the world of web apps, I find the agent's ability to write good e2e tests to be a real game changer. Turns out with enough rigor you can write pretty stable mostly not flaky e2e tests. And even flaky ones are fixed quickly due to a fuck ton of assertions at every step.
Test code looks like a mess, even more than the usual LLM code. takes a while to let it go. Test report looks beautiful though.