alt Hacker NewsYes, those ones would be at least a somewhat-plausible simulation of a real scenario people care about: a once-clean codebase that was allowed to become messy by a succession of insufficiently-careful vibeslop PRs.
I'm not a huge fan of their methodology for the AI-degraded cases either (ideally one would set up the mirror pairs by taking some real repositories and rewinding history a month or so and then having a succession of independent agents reimplement each bit of feature work and bugfixes over that period of time), but it's at least a coarse approximation whereas I just don't trust the cleanup methodology to resemble anything real in the first place.
Our initial suggestion was to do something along the lines of your proposal. But we found that when we ask an agent to implement features for `t-n`^th PR, even when we are overly specific makes the code rather divergent, to the point that sometimes the `t-n+1`th task description doesn't really make a lot of sense.
In fact, there are some papers (that we cited) which create a set of tasks doing exactly this, and it is non-trivial [1].
[1] https://arxiv.org/html/2603.24755