Twenty-two commits to change one line.
On Friday, Anthropic released version 5 across all their models. I was curious after all the Fable hype and just hadn't found the right problem to throw at a Fable model. I decided using an Opus 5 local agent to upgrade my code review agents from Opus 4.8 to Opus 5 would be a low risk way to experience the new models. The upgrade seemed simple. One line in a workflow file, pointing the review agents at the new model. Claude was going to do the work. How long could it take?
Twenty-two commits. Twenty-three review rounds. Two days.
None of those commits touched application code. Not one. This was a harness project: build and instrument the review infrastructure itself. It took 22 commits and a merged PR of 18 files, +2717/−134 lines of code, to get there.
I went in thinking I was doing a technology evaluation. I ended up doing something else entirely.
