Layering Claude Code: Jev handles small decisions, Opus only plans
The author pulls Opus 5.5 out of daily execution, letting Jev handle small decisions like tool choice and file checks while Sonnet does the work and Fable advises, with one run catching 2 skipped tests.
I DELIBERATELY STOPPED OPUS 5.5 FROM DOING MOST OF THE WORK. AND THE STACK GOT BETTER. I wanted to see what would happen if I stopped using the strongest model as a universal employee inside Claude Code. I left Opus 5.5 with the main session, planning, hard decisions, and final review. Sonnet 5.5 does the regular work: writes code, runs tests, reads the codebase, and looks for docs. Fable 5.1 sits next to it as an advisor. it sees the whole session, but stays quiet until it actually notices a problem. and Jev sits between them. it handles small decisions like choosing a tool, checking a file, or deciding whether to keep going, so Opus doesn't have to wake up for every single step. one run showed exactly why I wanted this setup. the worker finished the task. the tests were green. Opus was already about to close the work. Fable noticed 2 skipped tests. the task went back, Sonnet finished the missing work, it ended with 50 passed, and only after that did Opus send the final result. > Claude Code - the whole workflow > Opus 5.5 - planning + final review > Sonnet 5.5 - coding + tests + research > Fable 5.1 - advisor > Jev - routing + small decisions and this is more interesting to me right now than another benchmark. the question is no longer just which model is smarter. the question is why the most expensive model should see every decision inside your agent stack at all. the video shows the whole run. in the article, I went deeper into what happens when you start removing big models from the places where they were never needed in the first place.
This post quotes another post: x.com/model_culture/status/2105354309680435332