Taken to its logical conclusion, what you are saying is do not write (or commit? but in practice, why write them if not to run in CI) any tests except for end-to-end tests covering actual use cases. In theory, even make them generic enough so they are not affected by the implementation. Perhaps even employ LLMs there ("check that a customer can provide their address for their order by using a headless browser").

It is a strong disagree from me: end-to-end tests have always been fragile and slow, and feedback loop time is the boundary at which any coder (agentic or human) needs to operate on. If your agents need to wait 2h to see if their every change is valid, you'll be beat by humans doing properly structured "just enough" testing.

That isn't the logical conclusion though. I specificly said find places where change would be too complex to attempt anyway which breaks your conclusion. This lets you find plenty of places to jump in and write a test. (You will still be wrong but less often and generally you know it will be a hard change before you start making it)

though I find in practice end to end tests are not that fragile. It took us a decade of effort to find and mitigate all the little issues that make them fragile though so perhaps you don't want to go that far. I wish I could make the end to end tests faster though, but fragile they are not.

I am a bit perplexed at your claim that end-to-end tests are not fragile in general (my claim) with a counter how you spent a decade on not making them fragile in one particular case?

I am not disagreeing most projects evolve test suites which have duplicated, useless tests as a majority. But it can be done better.

I have also spent a decade on some tiny unit tests that were fragile.