Yep, this all actually started because of experimenting with my own open source project https://officefloor.net (giving full disclosure)

I was testing the additive pipeline style of OfficeFloor against the mutative handler style of Spring. I was looking to see what factors could be used to allow AI to make long on going changes (experiment is 60 changes to an end point, where all add functionality and every 4th change is mutative on existing rules). Then I watch how AI manages to make the 60 changes in each architecture.

I've done many runs and you are quite right about Goodhart effect in giving it the metric. Never knew Spring code could be written so badly.

I've tried runs with better prompting also and I'm starting to find the key factor is actually the architecture itself.

From my initial findings, it's seeming that additive pipeline architectures hold up much better against AI slop than our typically single method web handler architectures.